Tal Shahar - Academia.edu (original) (raw)
Papers by Tal Shahar
Journal of Neurological Surgery Part B: Skull Base, 2013
Complete tumor resection with preservation or improvement of visual function is the goal of tuber... more Complete tumor resection with preservation or improvement of visual function is the goal of tuberculum sellae meningioma (TSM) treatment. The authors retrospectively reviewed 51 patients treated surgically for TSM between 2003 and 2010, with special attention to surgical technique, visual outcomes, and prognostic factors for treatment outcome. All patients were operated via the lateral subfrontal approach. The cohort mean age and Karnofsky performance status (KPS) on admission was 57.1 ± 13.6 and 84.3 ± 11.7, respectively. The most common presenting sign was visual impairment. The mean tumor size was 29.4 ± 10.7 mm. In 45 of the patients (88.2%), gross total resection was achieved. Improvement and/or preservation of visual acuity and visual field were achieved in 95.9% and 85.3%, respectively. Visual functions on admission were found to be the strongest predictors for postoperative improvement in visual outcome, followed by better KPS on admission, smaller tumor size, and young age. Postoperative neurological complications included cerebrospinal fluid (CSF) leak, meningitis, and postoperative seizures. TSM can be safely operated on through the lateral subfrontal approach. A high percentage of complete tumor resection and excellent visual outcomes are achieved using this technique. Surgical treatment in the early stage of the disease may result in a better visual outcome.
Clinical Investigation, 2013
Journal of neurosurgery, 2015
The differential diagnosis of a brain lesion with two discordant pathology reports includes the p... more The differential diagnosis of a brain lesion with two discordant pathology reports includes the presence of collision tumor, metaplastic changes, and labeling errors that occurred during the processing of the specimen. The authors present a case in which the first brain biopsy from a 47-year-old patient with a history of heavy smoking was compatible with metastatic small cell carcinoma, and the second biopsy taken during decompression craniotomy 3 weeks later was compatible with WHO Grade IV glioblastoma. Using short tandem repeat (STR) analysis of the two specimens and nontumor-derived patient DNA, the authors found that the two specimens did not belong to the same individual. The authors conclude that allele imbalance or loss of heterozygosity detected by STR analysis is a reliable and valuable diagnostic tool for clarifying discrepancies in discordant pathology reports.
Journal of Neuroscience, 2004
Oxytocin-and vasopressin-producing magnocellular neurons (MCNs) of the hypothalamo-neurohypophysi... more Oxytocin-and vasopressin-producing magnocellular neurons (MCNs) of the hypothalamo-neurohypophysial system are the only neuronal phenotypes present in the rat supraoptic nucleus (SON). Laser microdissection of the SON, extraction and T7-based amplification of its RNAs, and analysis of the resulting cDNAs by hybridization on a 35, 319 element DNA microarray have provided a detailed composite view of the gene expression profile of the MCNs. The genes expressed in the SON were compared with those expressed in a reference tissue consisting of total hypothalamus, and this "expression ratio" indicated which genes were preferentially expressed in the SON. Of the 26,000 unique genes on the array, 1385 were found to be expressed in the SON at levels more than two times greater than in the hypothalamus as a whole. Of these, 123 were expressed Ն3.4-fold higher in the SON versus hypothalamus. Most of these preferentially expressed genes were not previously known to be expressed in the MCNs. Quantitative and double-label in situ hybridization histochemistry was used selectively to confirm a number of these microarray observations and to evaluate the osmotic regulation and cell-specific expression of these genes, respectively.
Journal of Neuroscience, 2004
Axotomy typically leads to retrograde neuronal degeneration in the CNS. Studies in the hypothalam... more Axotomy typically leads to retrograde neuronal degeneration in the CNS. Studies in the hypothalamo-neurohypophysial system (HNS) have suggested that neural activity is supportive of magnocellular neuronal (MCN) survival after axotomy. In this study, we directly test this hypothesis by inhibiting neural activity in the HNS, both in vivo and in vitro, by the use of tetrodotoxin (TTX). After median eminence compression to produce axonal injury, unilateral superfusion of 3 M TTX into the rat supraoptic nucleus (SON), delivered with the use of a miniature osmotic pump for 2 weeks in vivo, produced a decrease in the number of surviving MCNs in the TTX-treated SON, compared with the contralateral untreated side of the SON. In vitro application of 2.5 M TTX for 2 weeks to the SON in organotypic culture produced a 73% decrease in the surviving MCNs, compared with untreated control cultures. Raising the extracellular KCl in the culture medium to 25 mM rescued the MCNs from the axotomy-and TTX-induced cell death. These data support the proposal that after axotomy, neural activity is neuroprotective in the HNS.
Stress: The International Journal on the Biology of Stress, 2007
Neuronal inputs from the forebrain and the brainstem to sympathetic preganglionic neurons in the ... more Neuronal inputs from the forebrain and the brainstem to sympathetic preganglionic neurons in the spinal cord were investigated by the transneuronal retrograde tracing technique using pseudorabies virus in intact and brainstem-lesioned rats. After unilateral subcutaneous viral inoculations into the hind limb of intact rats, infected neurons were then visualized by immunostaining. At 3.5 days after inoculation, infected neurons appeared in the thoracic (T10) intermediolateral (IML) cell column. On the 4th day, infected neurons were present in the C1, A5, A6, A7 catecholamine cell groups and the rostral ventromedial medulla (RVMM). On the 5th day, viral labeling was seen in the hypothalamic paraventricular and arcuate nuclei and the lateral hypothalamic area. In all of these nuclei, the infected cells appeared bilaterally. However, the appearance of virus-labeled cells in these nuclei was unilateral following unilateral coronal sections between the medulla and the spinal cord (depending on the side of hemisection, but not on the site of virus inoculation). Midsagittal sections throughout the entire medulla oblongata did not alter the topographical pattern of virus-infected neurons in the forebrain or the brainstem. These findings indicate that descending fibers to the spinal neurons may not cross over in the lower brainstem but that they decussate within the spinal cord.
Neurosurgery, 2014
Preoperative diffusion tensor imaging (DTI) is used to demonstrate corticospinal tract (CST) posi... more Preoperative diffusion tensor imaging (DTI) is used to demonstrate corticospinal tract (CST) position. Intraoperative brain shifts may limit preoperative DTI value, and studies characterizing such shifts are lacking. To examine tumor characteristics that could predict intraoperative shift in tumor-to-CST distance using high-field intraoperative magnetic resonance imaging. We retrospectively evaluated preoperative and intraoperative DTIs, tumor pathology, and imaging characteristics of patients who underwent resection of an intra-axial tumor adjacent to the CST to identify covariates that significantly affected shift in tumor-to-CST distance. For validation, we analyzed data from a separate, 20-patient cohort. In the first cohort, the mean intraoperative shift in the tumor-to-CST distance was 3.18 ± 3.58 mm. The mean shift for the 20 patients with contrast and the 5 patients with non-contrast-enhancing tumors was 3.93 ± 3.64 and 0.18 ± 0.18 mm, respectively (P < .001). No association was found between intraoperative shift in tumor-to-CST distance and tumor pathology, tumor volume, edema volume, preoperative tumor-to-CST distance, or extent of resection. According to receiver-operating characteristic analysis, nonenhancement predicted a tumor-to-CST distance shift of ≤ 0.5 mm, with a sensitivity of 100% and a specificity of 75%. We validated these findings using the second cohort. For nonenhancing intra-axial tumors, preoperative DTI is a reliable method for assessing intraoperative tumor-to-CST distance because of minimal intraoperative shift, a finding that is important in the interpretation of subcortical motor evoked potential to maximize extent of resection and to preserve motor function. In resection of intra-axial enhancing tumors, intraoperative imaging studies are crucial to compensate for brain shift.
Neuroscience, 2009
The cytokine transforming growth factor α (TGFα) has proangiogenic and proneurogenic effects and ... more The cytokine transforming growth factor α (TGFα) has proangiogenic and proneurogenic effects and can potentially reduce infarct volumes. Therefore, we administered TGFα or vehicle directly into the area surrounding the infarct in female mice that received gender-mismatched bone marrow transplants from GFP-expressing males prior to undergoing permanent middle cerebral artery occlusion. Newborn cells were tracked with BrdU labeling and immunohistochemistry at 90 days after stroke onset. We also studied the ingress of bone marrow derived cells into the ischemic brain to determine whether such cells contribute to angiogenesis or neurogenesis. Infarct volumes were measured at 90 days post stroke. The results show that TGFα led to significant increments in the number of newborn neurons and glia in the ischemic hemisphere. TGFα also led to significant increments in the number of bone marrow derived cells entering into the ischemic hemisphere. Most of these cells did not label with BrdU and represented endothelial cells that incorporated into blood vessels in the infarct border zone. Our results also show that infarct size was significantly reduced in animals treated with TGFα compared with controls. These results suggest that TGFα can induce angiogenesis, neurogenesis and neuroprotection after stroke. At least part of the pro-angiogenic effect appears to be secondary to the incorporation of bone marrow derived endothelial cells into blood vessels in the infarct border zone.
Journal of Neurosurgery, 2011
Preserving motor function is a major challenge in surgery for intraaxial brain tumors. Navigation... more Preserving motor function is a major challenge in surgery for intraaxial brain tumors. Navigation systems are unreliable in predicting the location of the corticospinal tracts (CSTs) because of brain shift and the inability of current intraoperative systems to produce reliable diffusion tensor imaging data. The authors describe their experience with elaborate neurophysiological assessment and tractography-based navigation, corrected in real time by 3D intraoperative ultrasonography (IOUS) to identify motor pathways during subcortical tumor resection. A retrospective analysis was conducted in 55 patients undergoing resection of tumors located within or in proximity to the CSTs at the authors' institution between November 2007 and June 2009. Corticospinal tract tractography was coregistered to surgical navigation-derived images in 42 patients. Direct cortical-stimulated motor evoked potentials (dcMEPs) and subcortical-stimulated MEPs (scrtMEPs) were recorded intraoperatively to assess function and estimate the distance from the CSTs. Intraoperative ultrasonography updated the navigation imaging and estimated resection proximity to the CSTs. Preoperative clinical motor function was compared with postoperative outcome at several time points and correlated with incidences of intraoperative dcMEP alarm and low scrtMEP values. The threshold level needed to elicit scrtMEPs was plotted against the distance to the CSTs based on diffusion tensor imaging tractography after brain shift compensation with 3D IOUS, generating a trend line that demonstrated a linear order between these variables, and a relationship of 0.97 mA for every 1 mm of brain tissue distance from the CSTs. Clinically, 39 (71%) of 55 patients had no postoperative deficits, and 9 of the remaining 16 improved to baseline function within 1 month. Seven patients had varying degrees of permanent motor deficits. Subcortical stimulation was applied in 45 of the procedures. The status of 32 patients did not deteriorate postoperatively (stable or improved motor status): 27 of them (84%) displayed minimum scrtMEP thresholds > 7 mA. Six patients who experienced postoperative deterioration quickly recovered (within 5 days) and displayed minimum scrtMEP thresholds > 6.8 mA. Five of the 7 patients who had late (> 5 days postoperatively) or no recovery had minimal scrtMEP thresholds < 3 mA. An scrtMEP threshold of 3 mA was found to be the cutoff point below which irreversible disruption of CST integrity may be anticipated (sensitivity 83%, specificity 95%). Combining elaborate neurophysiological assessment, tractography-based neuronavigation, and updated IOUS images provided accurate localization of the CSTs and enabled the safe resection of tumors approximating these tracts. This is the first attempt to evaluate the distance from the CSTs using the threshold of subcortical monopolar stimulation with real-time IOUS for the correction of brain shift. The linear correlation between the distance to the CSTs and the threshold of subcortical stimulation producing a motor response provides an intraoperative technique to better preserve motor function.
Journal of Neuropathology and Experimental Neurology, 2007
Multiple sclerosis (MS), the most common nontraumatic cause of neurologic disability in young adu... more Multiple sclerosis (MS), the most common nontraumatic cause of neurologic disability in young adults in economically developed countries, is characterized by inflammation, gliosis, demyelination, and neuronal degeneration in the CNS. Bone marrow transplantation (BMT) can suppress inflammatory disease in a majority of patients with MS but retards clinical progression only in patients treated in the early stages of the disease. Here, we applied BMT in a mouse model of neuroinflammation, experimental autoimmune encephalomyelitis (EAE), and investigated the kinetics of reconstitution of the immune system in the periphery and in the CNS using bone marrow cells isolated from syngeneic donors constitutively expressing green fluorescent protein. This approach allowed us to dissect the contribution of donor cells to the turnover of resident microglia and to the pathogenesis of observed disease relapses after BMT. BMT effectively blocked or delayed EAE development when mice were treated early in the course of the disease but was without effect in mice with chronic disease. We found that there is minimal overall replacement of host microglia with donor cells in the CNS and that newly transplanted cells do not appear to contribute to disease progression. In contrast, EAE relapses are accompanied by the robust activation of endogenous microglial and macroglial cells, which further involves the maturation of endogenous Olig2 glial progenitor cells into reactive astrocytes through the cytoplasmic translocation of Olig2 and the expression of CD44 on the cellular membrane. The observed maturation of large numbers of reactive astrocytes from glial progenitors and the chronic activation of host microglial cells have relevance for our understanding of the resident glial response to inflammatory injury in the CNS. Our data indicate that reactivation of a local inflammatory process after BMT is sustained predominantly by endogenous microglia/macrophages.
Journal of Neuro-Oncology, 2012
Convection-enhanced delivery (CED) of compounds into brain tumors reportedly circumvents the bloo... more Convection-enhanced delivery (CED) of compounds into brain tumors reportedly circumvents the blood brain barrier. CED intends to increase drug delivery to malignant cells, reaching high local therapeutic concentration and decreasing or eliminating systemic side effects. Clinical experience and published data on catheter placement (CP) surgery are scarce. We propose practical and technical guidelines for planning CED based on our experience. We retrospectively analyzed the medical charts and relevant neuroimages of 25 patients following the insertion of 64 CED catheters. The patients were enrolled in at least one of four clinical trials using CED for treating recurrent glioblastoma multiforme in our institution between 2003-2006. Intra- and postoperative complications related to CP surgery and the difficulties and pitfalls of planning were evaluated. There were 29 CP surgeries. Forty-four peritumoral brain tissue catheters were inserted in 16 CP surgeries following tumor resection in 16 patients, and 20 catheters were placed into the tumor in 13 procedures in 10 patients. The lesions were in or near eloquent brain tissue areas in 13 of all CP surgeries. Complications included increased edema (31%), infection (6.9%), bleeding (6.9%) and seizures (13.8%). Significant neurological deterioration occurred in 4 patients (13.8%). Difficulties in adhering to CP surgery guidelines included lesion site (superficial, mesial temporal lobe, proximity to CSF spaces), proximity to eloquent cortical areas, tissue density that interfered with the trajectory, and technical limitations of stereotactic instruments. CED procedures for high-grade gliomas may be associated with surgical morbidity. Adherence to guidelines might be difficult because of lesion site and complicated by brain and tumor tissue characteristics. This should be considered while planning clinical trials that use convection-based technology.
Journal of Clinical Neuroscience, 2012
The impact of enrollment in a clinical study on the survival of patients with glioblastoma has no... more The impact of enrollment in a clinical study on the survival of patients with glioblastoma has not been established. We retrospectively analyzed 564 patients with newly diagnosed glioblastoma treated between 1995 and 2008. They were divided into those enrolled in a clinical trial and randomized to a treatment or control arm, and those not enrolled and who received best standard of care (BSC). The three groups were matched for age and Karnofsky performance scale (KPS) score at presentation, and included only patients who underwent at least one tumor resection. Survival analysis was performed and multivariate Cox proportional hazards model and recursive partitioning analysis (RPA) identified predictors of survival. Following the matching process, 261 patients remained to form the final cohort. Of the 124 patients enrolled in a study, 81 (31.0%) were randomized to the treatment and 43 (16.5%) to the control arms. The overall median survival for the BSC (n=137), control, and treatment groups was 11.57 months (95% confidence interval [CI], 10.41-12.73), 16.27 months (95% CI, 14.10-18.43) and 16.10 months (95% CI, 14.34-17.86), respectively (p=0.002). Participation in a clinical trial, regardless of the arm, was a significant predictor of survival, as were age and KPS at diagnosis. The RPA also demonstrated a favorable impact of participation in a clinical trial. Additional tumor resections and various treatment modalities were administered with significantly higher frequency among patients enrolled in clinical studies. Thus, enrollment in a clinical study carried a significant survival advantage for patients with glioblastoma, raising practical and ethical issues regarding the quality of care of patients who receive "standard" therapy.
Frontiers in Neuroscience, 2010
We studied the effect of permanent unilateral middle cerebral artery occlusion (PMCAO) on the gen... more We studied the effect of permanent unilateral middle cerebral artery occlusion (PMCAO) on the generation of bone marrow (BM)-derived astrocytes in female mice previously transplanted with enchanced green fluorescent protein-expressing BM from male donors. In addition to an untreated PMCAO group, one group of mice also received intracerebral infusion of transforming growth factor-alpha, resulting in a decrease in the size of the infarct. Two months after PMCAO, we found a specific type of astrocyte of BM origin in the side of the injury, near the lesion. These astrocytes did not express glial fibrillary acidic protein (GFAP) by conventional fluorescence immunostaining; however, GFAP was easily detectable by tyramide signal amplification. These cells also expressed S100b, confirming their astrocytic character. Unlike the endogenous reactive astrocytes, these BMderived astrocytes did not proliferate during the first week of ischemia and did not contribute to the glial scar formation. Transforming growth factor-alpha infusion increased the number of BM-derived astrocytes, without affecting their distribution. Interestingly, exclusively by tyramide signal amplification staining, we found that endogenous astrocytes displaying an identical morphology were also present in control mouse and human brains. Our data demonstrate that a subpopulation of nonreactive astrocytes expressing low levels of GFAP can originate from transplanted BM in the ischemic brain. We believe that these cells represent a subpopulation of astrocytes earlier considered to be GFAP negative. The high number of astrocytes with identical morphology and chemical character in control brains suggest that these type of astrocytes may have important functional role in the central nervous system that calls for further studies.
Experimental Cell Research, 2007
The green fluorescent protein (GFP) is among the most commonly used expression markers in biology... more The green fluorescent protein (GFP) is among the most commonly used expression markers in biology. GFP-tagged cells have played a particularly important role in studies of cell lineage. Sensitive detection of GFP is crucially important for such studies to be successful, and problems with detection may account for discrepancies in the literature regarding the possible fate choices of stem cells. Here we describe a very sensitive technique for visualization of GFP. Using it we can detect about 90% of cells of donor origin while we could only see about 50% of these cells when we employ the methods that are in general use in other laboratories. In addition, we provide evidence that some cells permanently silence GFP expression. In the case of the progeny of bone marrow stem cells, it appears that the more distantly related they are to their precursors, the more likely it is that they will turn off the lineage marker.
Endocrinology, 2005
Hypoosmolality produces a dramatic inhibition of vasopressin (VP) and oxytocin gene expression in... more Hypoosmolality produces a dramatic inhibition of vasopressin (VP) and oxytocin gene expression in the supraoptic nucleus (SON). This study examines the effect of sustained hypoosmolality on global gene expression in the oxytocin and VP magnocellular neurons of the hypothalamo-neurohypophysial system, to identify genes associated with the magnocellular neuron's adaptation to this physiological condition. Using laser microdissection of the SON, T7-based linear amplification of its RNA, and a 35,319-element cDNA microarray, we compare gene expression profiles between SONs in normoosmolar (control), 1-desamino-[8-D-arginine]-VP-treated normoosmolar, and hypoosmolar rats. We found 4959 genes with statistically significant differences in expression between normosmolar control and the hypoosmolar SONs, with 1564 of these differing in expression by more than 2-fold. These genes serve a wide variety of functions, and most were up-regulated in gene expression in hypoosmolar compared with control SONs. Of these, 90 were preferentially expressed in the SON, and 44 coded for transcription-related factors, of which 15 genes were down-regulated and 29 genes were up-regulated in the hypoosmolar rat SONs. None of these transcription-related factor genes significantly changed in expression after sustained 1-desamino-[8-D-arginine]-VP-treatment alone, indicating that these changes were associated with the hypoosmolar state and not due solely to a decreased activity in the SON. Quantitative in situ hybridization histochemistry was selectively used to confirm and extend these microarray observations. These results indicate that the hypoosmolar state is accompanied by a global, but selective, increase in expression of a wide variety of regulatory genes in the SON.
Blood, 2008
Granulocyte colony-stimulating factor (G-CSF) induces proliferation of bone marrow-derived cells.... more Granulocyte colony-stimulating factor (G-CSF) induces proliferation of bone marrow-derived cells. G-CSF is neuroprotective after experimental brain injury, but the mechanisms involved remain unclear. Stem cell factor (SCF) is a cytokine important for the survival and differentiation of hematopoietic stem cells. Its receptor (c-kit or CD117) is present in some endothelial cells. We aimed to determine whether the combination of G-CSF/SCF induces angiogenesis in the central nervous system by promoting entry of endothelial precursors into the injured brain and causing them to proliferate there. We induced permanent middle cerebral artery occlusion in female mice that previously underwent sex-mismatched bone marrow transplantation from enhanced green fluorescent protein (EGFP)-expressing mice. G-CSF/SCF treatment reduced infarct volumes by more than 50% and resulted in a 1.5-fold increase in vessel formation in mice with stroke, a large percentage of which contain endothelial cells of bone marrow origin. Most cells entering the brain maintained their bone marrow identity and did not transdifferentiate into neural cells. G-CSF/SCF treatment also led to a 2-fold increase in the number of newborn cells in the ischemic hemisphere. These findings suggest that G-CSF/SCF treatment might help recovery through induction of bone marrow-derived angiogenesis, thus improving neuronal survival and functional outcome.
World Neurosurgery, 2015
Whole brain radiation treatment (WBRT) is considered standard treatment for BM. However, exposing... more Whole brain radiation treatment (WBRT) is considered standard treatment for BM. However, exposing large volumes of normal brain tissue to irradiation can cause neurotoxicity. This study describes our experience with 100 consecutive patients with brain metastases who were managed with surgical extirpation followed by stereotactic radiosurgery (SRS) to the resection cavity. Patients with 1-3 brain metastases (BM), who underwent resection of 1-2 BM between June 2005 and December 2013, were treated with SRS directed to the tumor cavity and for any synchronous BM. Local and distant treatment failures were determined based on neuroimaging. Kaplan-Meier curves were generated for local and distant failure rates and overall survival. One hundred and two resection cavities were treated with SRS in 100 consecutive patients. Thirty-two additional synchronous metastases were treated in 27 patients during the same session. The median overall survival was 18.9 months. Local control rate at 1 year was 84%. Longer delays between surgery and SRS were associated with increased risk of local failure (hazard ratio, -1.46; P = 0.02). Distant progression occurred in 44% of the patients at a mean of 8.8 ± 6.6 months after SRS treatment. Ten cases of leptomeningeal spread occurred around the resection cavities (9.8%). Central nervous system failure was not significantly associated with survival. Multivariate Cox regression analysis showed that recursive partitioning analysis and active systemic disease were significantly associated with survival. The strategy described provides acceptable local disease control when compared with WBRT following surgery. This approach can delay and even annul WBRT in the majority of selected BM patients, especially recursive partitioning analysis class I patients. SRS should be scheduled as soon as possible after surgery.
Journal of Neurological Surgery Part B: Skull Base, 2013
Complete tumor resection with preservation or improvement of visual function is the goal of tuber... more Complete tumor resection with preservation or improvement of visual function is the goal of tuberculum sellae meningioma (TSM) treatment. The authors retrospectively reviewed 51 patients treated surgically for TSM between 2003 and 2010, with special attention to surgical technique, visual outcomes, and prognostic factors for treatment outcome. All patients were operated via the lateral subfrontal approach. The cohort mean age and Karnofsky performance status (KPS) on admission was 57.1 ± 13.6 and 84.3 ± 11.7, respectively. The most common presenting sign was visual impairment. The mean tumor size was 29.4 ± 10.7 mm. In 45 of the patients (88.2%), gross total resection was achieved. Improvement and/or preservation of visual acuity and visual field were achieved in 95.9% and 85.3%, respectively. Visual functions on admission were found to be the strongest predictors for postoperative improvement in visual outcome, followed by better KPS on admission, smaller tumor size, and young age. Postoperative neurological complications included cerebrospinal fluid (CSF) leak, meningitis, and postoperative seizures. TSM can be safely operated on through the lateral subfrontal approach. A high percentage of complete tumor resection and excellent visual outcomes are achieved using this technique. Surgical treatment in the early stage of the disease may result in a better visual outcome.
Clinical Investigation, 2013
Journal of neurosurgery, 2015
The differential diagnosis of a brain lesion with two discordant pathology reports includes the p... more The differential diagnosis of a brain lesion with two discordant pathology reports includes the presence of collision tumor, metaplastic changes, and labeling errors that occurred during the processing of the specimen. The authors present a case in which the first brain biopsy from a 47-year-old patient with a history of heavy smoking was compatible with metastatic small cell carcinoma, and the second biopsy taken during decompression craniotomy 3 weeks later was compatible with WHO Grade IV glioblastoma. Using short tandem repeat (STR) analysis of the two specimens and nontumor-derived patient DNA, the authors found that the two specimens did not belong to the same individual. The authors conclude that allele imbalance or loss of heterozygosity detected by STR analysis is a reliable and valuable diagnostic tool for clarifying discrepancies in discordant pathology reports.
Journal of Neuroscience, 2004
Oxytocin-and vasopressin-producing magnocellular neurons (MCNs) of the hypothalamo-neurohypophysi... more Oxytocin-and vasopressin-producing magnocellular neurons (MCNs) of the hypothalamo-neurohypophysial system are the only neuronal phenotypes present in the rat supraoptic nucleus (SON). Laser microdissection of the SON, extraction and T7-based amplification of its RNAs, and analysis of the resulting cDNAs by hybridization on a 35, 319 element DNA microarray have provided a detailed composite view of the gene expression profile of the MCNs. The genes expressed in the SON were compared with those expressed in a reference tissue consisting of total hypothalamus, and this "expression ratio" indicated which genes were preferentially expressed in the SON. Of the 26,000 unique genes on the array, 1385 were found to be expressed in the SON at levels more than two times greater than in the hypothalamus as a whole. Of these, 123 were expressed Ն3.4-fold higher in the SON versus hypothalamus. Most of these preferentially expressed genes were not previously known to be expressed in the MCNs. Quantitative and double-label in situ hybridization histochemistry was used selectively to confirm a number of these microarray observations and to evaluate the osmotic regulation and cell-specific expression of these genes, respectively.
Journal of Neuroscience, 2004
Axotomy typically leads to retrograde neuronal degeneration in the CNS. Studies in the hypothalam... more Axotomy typically leads to retrograde neuronal degeneration in the CNS. Studies in the hypothalamo-neurohypophysial system (HNS) have suggested that neural activity is supportive of magnocellular neuronal (MCN) survival after axotomy. In this study, we directly test this hypothesis by inhibiting neural activity in the HNS, both in vivo and in vitro, by the use of tetrodotoxin (TTX). After median eminence compression to produce axonal injury, unilateral superfusion of 3 M TTX into the rat supraoptic nucleus (SON), delivered with the use of a miniature osmotic pump for 2 weeks in vivo, produced a decrease in the number of surviving MCNs in the TTX-treated SON, compared with the contralateral untreated side of the SON. In vitro application of 2.5 M TTX for 2 weeks to the SON in organotypic culture produced a 73% decrease in the surviving MCNs, compared with untreated control cultures. Raising the extracellular KCl in the culture medium to 25 mM rescued the MCNs from the axotomy-and TTX-induced cell death. These data support the proposal that after axotomy, neural activity is neuroprotective in the HNS.
Stress: The International Journal on the Biology of Stress, 2007
Neuronal inputs from the forebrain and the brainstem to sympathetic preganglionic neurons in the ... more Neuronal inputs from the forebrain and the brainstem to sympathetic preganglionic neurons in the spinal cord were investigated by the transneuronal retrograde tracing technique using pseudorabies virus in intact and brainstem-lesioned rats. After unilateral subcutaneous viral inoculations into the hind limb of intact rats, infected neurons were then visualized by immunostaining. At 3.5 days after inoculation, infected neurons appeared in the thoracic (T10) intermediolateral (IML) cell column. On the 4th day, infected neurons were present in the C1, A5, A6, A7 catecholamine cell groups and the rostral ventromedial medulla (RVMM). On the 5th day, viral labeling was seen in the hypothalamic paraventricular and arcuate nuclei and the lateral hypothalamic area. In all of these nuclei, the infected cells appeared bilaterally. However, the appearance of virus-labeled cells in these nuclei was unilateral following unilateral coronal sections between the medulla and the spinal cord (depending on the side of hemisection, but not on the site of virus inoculation). Midsagittal sections throughout the entire medulla oblongata did not alter the topographical pattern of virus-infected neurons in the forebrain or the brainstem. These findings indicate that descending fibers to the spinal neurons may not cross over in the lower brainstem but that they decussate within the spinal cord.
Neurosurgery, 2014
Preoperative diffusion tensor imaging (DTI) is used to demonstrate corticospinal tract (CST) posi... more Preoperative diffusion tensor imaging (DTI) is used to demonstrate corticospinal tract (CST) position. Intraoperative brain shifts may limit preoperative DTI value, and studies characterizing such shifts are lacking. To examine tumor characteristics that could predict intraoperative shift in tumor-to-CST distance using high-field intraoperative magnetic resonance imaging. We retrospectively evaluated preoperative and intraoperative DTIs, tumor pathology, and imaging characteristics of patients who underwent resection of an intra-axial tumor adjacent to the CST to identify covariates that significantly affected shift in tumor-to-CST distance. For validation, we analyzed data from a separate, 20-patient cohort. In the first cohort, the mean intraoperative shift in the tumor-to-CST distance was 3.18 ± 3.58 mm. The mean shift for the 20 patients with contrast and the 5 patients with non-contrast-enhancing tumors was 3.93 ± 3.64 and 0.18 ± 0.18 mm, respectively (P < .001). No association was found between intraoperative shift in tumor-to-CST distance and tumor pathology, tumor volume, edema volume, preoperative tumor-to-CST distance, or extent of resection. According to receiver-operating characteristic analysis, nonenhancement predicted a tumor-to-CST distance shift of ≤ 0.5 mm, with a sensitivity of 100% and a specificity of 75%. We validated these findings using the second cohort. For nonenhancing intra-axial tumors, preoperative DTI is a reliable method for assessing intraoperative tumor-to-CST distance because of minimal intraoperative shift, a finding that is important in the interpretation of subcortical motor evoked potential to maximize extent of resection and to preserve motor function. In resection of intra-axial enhancing tumors, intraoperative imaging studies are crucial to compensate for brain shift.
Neuroscience, 2009
The cytokine transforming growth factor α (TGFα) has proangiogenic and proneurogenic effects and ... more The cytokine transforming growth factor α (TGFα) has proangiogenic and proneurogenic effects and can potentially reduce infarct volumes. Therefore, we administered TGFα or vehicle directly into the area surrounding the infarct in female mice that received gender-mismatched bone marrow transplants from GFP-expressing males prior to undergoing permanent middle cerebral artery occlusion. Newborn cells were tracked with BrdU labeling and immunohistochemistry at 90 days after stroke onset. We also studied the ingress of bone marrow derived cells into the ischemic brain to determine whether such cells contribute to angiogenesis or neurogenesis. Infarct volumes were measured at 90 days post stroke. The results show that TGFα led to significant increments in the number of newborn neurons and glia in the ischemic hemisphere. TGFα also led to significant increments in the number of bone marrow derived cells entering into the ischemic hemisphere. Most of these cells did not label with BrdU and represented endothelial cells that incorporated into blood vessels in the infarct border zone. Our results also show that infarct size was significantly reduced in animals treated with TGFα compared with controls. These results suggest that TGFα can induce angiogenesis, neurogenesis and neuroprotection after stroke. At least part of the pro-angiogenic effect appears to be secondary to the incorporation of bone marrow derived endothelial cells into blood vessels in the infarct border zone.
Journal of Neurosurgery, 2011
Preserving motor function is a major challenge in surgery for intraaxial brain tumors. Navigation... more Preserving motor function is a major challenge in surgery for intraaxial brain tumors. Navigation systems are unreliable in predicting the location of the corticospinal tracts (CSTs) because of brain shift and the inability of current intraoperative systems to produce reliable diffusion tensor imaging data. The authors describe their experience with elaborate neurophysiological assessment and tractography-based navigation, corrected in real time by 3D intraoperative ultrasonography (IOUS) to identify motor pathways during subcortical tumor resection. A retrospective analysis was conducted in 55 patients undergoing resection of tumors located within or in proximity to the CSTs at the authors' institution between November 2007 and June 2009. Corticospinal tract tractography was coregistered to surgical navigation-derived images in 42 patients. Direct cortical-stimulated motor evoked potentials (dcMEPs) and subcortical-stimulated MEPs (scrtMEPs) were recorded intraoperatively to assess function and estimate the distance from the CSTs. Intraoperative ultrasonography updated the navigation imaging and estimated resection proximity to the CSTs. Preoperative clinical motor function was compared with postoperative outcome at several time points and correlated with incidences of intraoperative dcMEP alarm and low scrtMEP values. The threshold level needed to elicit scrtMEPs was plotted against the distance to the CSTs based on diffusion tensor imaging tractography after brain shift compensation with 3D IOUS, generating a trend line that demonstrated a linear order between these variables, and a relationship of 0.97 mA for every 1 mm of brain tissue distance from the CSTs. Clinically, 39 (71%) of 55 patients had no postoperative deficits, and 9 of the remaining 16 improved to baseline function within 1 month. Seven patients had varying degrees of permanent motor deficits. Subcortical stimulation was applied in 45 of the procedures. The status of 32 patients did not deteriorate postoperatively (stable or improved motor status): 27 of them (84%) displayed minimum scrtMEP thresholds > 7 mA. Six patients who experienced postoperative deterioration quickly recovered (within 5 days) and displayed minimum scrtMEP thresholds > 6.8 mA. Five of the 7 patients who had late (> 5 days postoperatively) or no recovery had minimal scrtMEP thresholds < 3 mA. An scrtMEP threshold of 3 mA was found to be the cutoff point below which irreversible disruption of CST integrity may be anticipated (sensitivity 83%, specificity 95%). Combining elaborate neurophysiological assessment, tractography-based neuronavigation, and updated IOUS images provided accurate localization of the CSTs and enabled the safe resection of tumors approximating these tracts. This is the first attempt to evaluate the distance from the CSTs using the threshold of subcortical monopolar stimulation with real-time IOUS for the correction of brain shift. The linear correlation between the distance to the CSTs and the threshold of subcortical stimulation producing a motor response provides an intraoperative technique to better preserve motor function.
Journal of Neuropathology and Experimental Neurology, 2007
Multiple sclerosis (MS), the most common nontraumatic cause of neurologic disability in young adu... more Multiple sclerosis (MS), the most common nontraumatic cause of neurologic disability in young adults in economically developed countries, is characterized by inflammation, gliosis, demyelination, and neuronal degeneration in the CNS. Bone marrow transplantation (BMT) can suppress inflammatory disease in a majority of patients with MS but retards clinical progression only in patients treated in the early stages of the disease. Here, we applied BMT in a mouse model of neuroinflammation, experimental autoimmune encephalomyelitis (EAE), and investigated the kinetics of reconstitution of the immune system in the periphery and in the CNS using bone marrow cells isolated from syngeneic donors constitutively expressing green fluorescent protein. This approach allowed us to dissect the contribution of donor cells to the turnover of resident microglia and to the pathogenesis of observed disease relapses after BMT. BMT effectively blocked or delayed EAE development when mice were treated early in the course of the disease but was without effect in mice with chronic disease. We found that there is minimal overall replacement of host microglia with donor cells in the CNS and that newly transplanted cells do not appear to contribute to disease progression. In contrast, EAE relapses are accompanied by the robust activation of endogenous microglial and macroglial cells, which further involves the maturation of endogenous Olig2 glial progenitor cells into reactive astrocytes through the cytoplasmic translocation of Olig2 and the expression of CD44 on the cellular membrane. The observed maturation of large numbers of reactive astrocytes from glial progenitors and the chronic activation of host microglial cells have relevance for our understanding of the resident glial response to inflammatory injury in the CNS. Our data indicate that reactivation of a local inflammatory process after BMT is sustained predominantly by endogenous microglia/macrophages.
Journal of Neuro-Oncology, 2012
Convection-enhanced delivery (CED) of compounds into brain tumors reportedly circumvents the bloo... more Convection-enhanced delivery (CED) of compounds into brain tumors reportedly circumvents the blood brain barrier. CED intends to increase drug delivery to malignant cells, reaching high local therapeutic concentration and decreasing or eliminating systemic side effects. Clinical experience and published data on catheter placement (CP) surgery are scarce. We propose practical and technical guidelines for planning CED based on our experience. We retrospectively analyzed the medical charts and relevant neuroimages of 25 patients following the insertion of 64 CED catheters. The patients were enrolled in at least one of four clinical trials using CED for treating recurrent glioblastoma multiforme in our institution between 2003-2006. Intra- and postoperative complications related to CP surgery and the difficulties and pitfalls of planning were evaluated. There were 29 CP surgeries. Forty-four peritumoral brain tissue catheters were inserted in 16 CP surgeries following tumor resection in 16 patients, and 20 catheters were placed into the tumor in 13 procedures in 10 patients. The lesions were in or near eloquent brain tissue areas in 13 of all CP surgeries. Complications included increased edema (31%), infection (6.9%), bleeding (6.9%) and seizures (13.8%). Significant neurological deterioration occurred in 4 patients (13.8%). Difficulties in adhering to CP surgery guidelines included lesion site (superficial, mesial temporal lobe, proximity to CSF spaces), proximity to eloquent cortical areas, tissue density that interfered with the trajectory, and technical limitations of stereotactic instruments. CED procedures for high-grade gliomas may be associated with surgical morbidity. Adherence to guidelines might be difficult because of lesion site and complicated by brain and tumor tissue characteristics. This should be considered while planning clinical trials that use convection-based technology.
Journal of Clinical Neuroscience, 2012
The impact of enrollment in a clinical study on the survival of patients with glioblastoma has no... more The impact of enrollment in a clinical study on the survival of patients with glioblastoma has not been established. We retrospectively analyzed 564 patients with newly diagnosed glioblastoma treated between 1995 and 2008. They were divided into those enrolled in a clinical trial and randomized to a treatment or control arm, and those not enrolled and who received best standard of care (BSC). The three groups were matched for age and Karnofsky performance scale (KPS) score at presentation, and included only patients who underwent at least one tumor resection. Survival analysis was performed and multivariate Cox proportional hazards model and recursive partitioning analysis (RPA) identified predictors of survival. Following the matching process, 261 patients remained to form the final cohort. Of the 124 patients enrolled in a study, 81 (31.0%) were randomized to the treatment and 43 (16.5%) to the control arms. The overall median survival for the BSC (n=137), control, and treatment groups was 11.57 months (95% confidence interval [CI], 10.41-12.73), 16.27 months (95% CI, 14.10-18.43) and 16.10 months (95% CI, 14.34-17.86), respectively (p=0.002). Participation in a clinical trial, regardless of the arm, was a significant predictor of survival, as were age and KPS at diagnosis. The RPA also demonstrated a favorable impact of participation in a clinical trial. Additional tumor resections and various treatment modalities were administered with significantly higher frequency among patients enrolled in clinical studies. Thus, enrollment in a clinical study carried a significant survival advantage for patients with glioblastoma, raising practical and ethical issues regarding the quality of care of patients who receive "standard" therapy.
Frontiers in Neuroscience, 2010
We studied the effect of permanent unilateral middle cerebral artery occlusion (PMCAO) on the gen... more We studied the effect of permanent unilateral middle cerebral artery occlusion (PMCAO) on the generation of bone marrow (BM)-derived astrocytes in female mice previously transplanted with enchanced green fluorescent protein-expressing BM from male donors. In addition to an untreated PMCAO group, one group of mice also received intracerebral infusion of transforming growth factor-alpha, resulting in a decrease in the size of the infarct. Two months after PMCAO, we found a specific type of astrocyte of BM origin in the side of the injury, near the lesion. These astrocytes did not express glial fibrillary acidic protein (GFAP) by conventional fluorescence immunostaining; however, GFAP was easily detectable by tyramide signal amplification. These cells also expressed S100b, confirming their astrocytic character. Unlike the endogenous reactive astrocytes, these BMderived astrocytes did not proliferate during the first week of ischemia and did not contribute to the glial scar formation. Transforming growth factor-alpha infusion increased the number of BM-derived astrocytes, without affecting their distribution. Interestingly, exclusively by tyramide signal amplification staining, we found that endogenous astrocytes displaying an identical morphology were also present in control mouse and human brains. Our data demonstrate that a subpopulation of nonreactive astrocytes expressing low levels of GFAP can originate from transplanted BM in the ischemic brain. We believe that these cells represent a subpopulation of astrocytes earlier considered to be GFAP negative. The high number of astrocytes with identical morphology and chemical character in control brains suggest that these type of astrocytes may have important functional role in the central nervous system that calls for further studies.
Experimental Cell Research, 2007
The green fluorescent protein (GFP) is among the most commonly used expression markers in biology... more The green fluorescent protein (GFP) is among the most commonly used expression markers in biology. GFP-tagged cells have played a particularly important role in studies of cell lineage. Sensitive detection of GFP is crucially important for such studies to be successful, and problems with detection may account for discrepancies in the literature regarding the possible fate choices of stem cells. Here we describe a very sensitive technique for visualization of GFP. Using it we can detect about 90% of cells of donor origin while we could only see about 50% of these cells when we employ the methods that are in general use in other laboratories. In addition, we provide evidence that some cells permanently silence GFP expression. In the case of the progeny of bone marrow stem cells, it appears that the more distantly related they are to their precursors, the more likely it is that they will turn off the lineage marker.
Endocrinology, 2005
Hypoosmolality produces a dramatic inhibition of vasopressin (VP) and oxytocin gene expression in... more Hypoosmolality produces a dramatic inhibition of vasopressin (VP) and oxytocin gene expression in the supraoptic nucleus (SON). This study examines the effect of sustained hypoosmolality on global gene expression in the oxytocin and VP magnocellular neurons of the hypothalamo-neurohypophysial system, to identify genes associated with the magnocellular neuron's adaptation to this physiological condition. Using laser microdissection of the SON, T7-based linear amplification of its RNA, and a 35,319-element cDNA microarray, we compare gene expression profiles between SONs in normoosmolar (control), 1-desamino-[8-D-arginine]-VP-treated normoosmolar, and hypoosmolar rats. We found 4959 genes with statistically significant differences in expression between normosmolar control and the hypoosmolar SONs, with 1564 of these differing in expression by more than 2-fold. These genes serve a wide variety of functions, and most were up-regulated in gene expression in hypoosmolar compared with control SONs. Of these, 90 were preferentially expressed in the SON, and 44 coded for transcription-related factors, of which 15 genes were down-regulated and 29 genes were up-regulated in the hypoosmolar rat SONs. None of these transcription-related factor genes significantly changed in expression after sustained 1-desamino-[8-D-arginine]-VP-treatment alone, indicating that these changes were associated with the hypoosmolar state and not due solely to a decreased activity in the SON. Quantitative in situ hybridization histochemistry was selectively used to confirm and extend these microarray observations. These results indicate that the hypoosmolar state is accompanied by a global, but selective, increase in expression of a wide variety of regulatory genes in the SON.
Blood, 2008
Granulocyte colony-stimulating factor (G-CSF) induces proliferation of bone marrow-derived cells.... more Granulocyte colony-stimulating factor (G-CSF) induces proliferation of bone marrow-derived cells. G-CSF is neuroprotective after experimental brain injury, but the mechanisms involved remain unclear. Stem cell factor (SCF) is a cytokine important for the survival and differentiation of hematopoietic stem cells. Its receptor (c-kit or CD117) is present in some endothelial cells. We aimed to determine whether the combination of G-CSF/SCF induces angiogenesis in the central nervous system by promoting entry of endothelial precursors into the injured brain and causing them to proliferate there. We induced permanent middle cerebral artery occlusion in female mice that previously underwent sex-mismatched bone marrow transplantation from enhanced green fluorescent protein (EGFP)-expressing mice. G-CSF/SCF treatment reduced infarct volumes by more than 50% and resulted in a 1.5-fold increase in vessel formation in mice with stroke, a large percentage of which contain endothelial cells of bone marrow origin. Most cells entering the brain maintained their bone marrow identity and did not transdifferentiate into neural cells. G-CSF/SCF treatment also led to a 2-fold increase in the number of newborn cells in the ischemic hemisphere. These findings suggest that G-CSF/SCF treatment might help recovery through induction of bone marrow-derived angiogenesis, thus improving neuronal survival and functional outcome.
World Neurosurgery, 2015
Whole brain radiation treatment (WBRT) is considered standard treatment for BM. However, exposing... more Whole brain radiation treatment (WBRT) is considered standard treatment for BM. However, exposing large volumes of normal brain tissue to irradiation can cause neurotoxicity. This study describes our experience with 100 consecutive patients with brain metastases who were managed with surgical extirpation followed by stereotactic radiosurgery (SRS) to the resection cavity. Patients with 1-3 brain metastases (BM), who underwent resection of 1-2 BM between June 2005 and December 2013, were treated with SRS directed to the tumor cavity and for any synchronous BM. Local and distant treatment failures were determined based on neuroimaging. Kaplan-Meier curves were generated for local and distant failure rates and overall survival. One hundred and two resection cavities were treated with SRS in 100 consecutive patients. Thirty-two additional synchronous metastases were treated in 27 patients during the same session. The median overall survival was 18.9 months. Local control rate at 1 year was 84%. Longer delays between surgery and SRS were associated with increased risk of local failure (hazard ratio, -1.46; P = 0.02). Distant progression occurred in 44% of the patients at a mean of 8.8 ± 6.6 months after SRS treatment. Ten cases of leptomeningeal spread occurred around the resection cavities (9.8%). Central nervous system failure was not significantly associated with survival. Multivariate Cox regression analysis showed that recursive partitioning analysis and active systemic disease were significantly associated with survival. The strategy described provides acceptable local disease control when compared with WBRT following surgery. This approach can delay and even annul WBRT in the majority of selected BM patients, especially recursive partitioning analysis class I patients. SRS should be scheduled as soon as possible after surgery.