Biomedical subjects

N Duggal

Publications and source records attributed to N Duggal.

15 recordsLinked to original sources

PubMed2005

Spontaneous chronic spinal subdural hematoma associated with spinal arachnoiditis and syringomyelia.

Spontaneous chronic spinal subdural hematoma is rare. We describe a case of spontaneous chronic spinal subdural hematoma associated with arachnoiditis and syringomyelia in a 76-year old woman who presented with a 14-year history of progressive myelopathy. MRI scan revealed a thoraco-lumbar subdural cystic lesion and a thoracic syrinx. The patient underwent thoracic laminectomy and decompression of the lesion, which was a subdural hematoma. A myelotomy was performed to drain the syrinx. Pathological examination revealed features consistent with chronic subdural membrane. This report attempts to elucidate the pathogenesis of chronic spinal subdural hematoma. We discuss possible etiological factors in light of the current literature and pathogenesis of both spinal subdural hematoma and syrinx formation.

Aged↗

PubMed2002

Selective vulnerability of the lumbosacral spinal cord after cardiac arrest and hypotension.

BACKGROUND AND PURPOSE: It is generally accepted that the gray matter in the watershed area of the midthoracic level of the spinal cord is the ischemic watershed zone of the spinal cord. We performed a retrospective study to reevaluate the frequency and distribution of spinal cord injury after a global ischemic event. METHODS: Clinical files and neuropathology specimens of all adult patients with either a well-documented cardiac arrest or a severe hypotensive episode, as well as pathologically confirmed ischemic encephalopathy and/or myelopathy, were reviewed by an independent reviewer. RESULTS: Among 145 cases satisfying selection criteria, ischemic myelopathy was found in 46% of patients dying after either a cardiac arrest or a severe hypotensive episode. Among the patients with myelopathy, predominant involvement of the lumbosacral level with relative sparing of thoracic levels was observed in >95% of cardiac arrest and hypotensive patients. None of the examined patients developed neuronal necrosis limited to the thoracic level only. CONCLUSIONS: Our findings indicate a greater vulnerability of neurons in the lumbar or lumbosacral spinal cord to ischemia than other levels of the spinal cord.

Adolescent↗

PubMed2001

Nestin expression in cortical dysplasia.

OBJECT: It is recognized that cortical dysplasia (CD) is associated with an increased incidence of glioneuronal neoplasms. Among hypothetical considerations, there is the possibility that CD and other neuronal migration abnormalities harbor dysmature cells with the potential to give rise to glioneuronal neoplasms. Such cells, if present, would be reasonably expected to display immature features. The goal of the present study was to characterize the expression of nestin, a neuroepithelial precursor/stem cell antigen, in CD, along with other pathological and clinical features of this entity. METHODS: Clinical and surgical features of 10 recent cases meeting the histological criteria for CD were reviewed. Expressions of nestin, MAP2, neurofilament, and glial fibrillary acidic protein (GFAP) were assessed using immunohistochemical analysis and confocal scanning laser microscopy. Immunoreactivity for both glial and neuronal antigens as well as nestin was found in a select group of cells within regions of CD. Immunohistochemical and confocal microscopic findings demonstrated that these cells with neuronal or ambiguous features are a mixed population, some of which are dysmature neurons (positive for nestin and MAP2), whereas others are astrocytic (positive for nestin and GFAP). CONCLUSIONS: Further insight into the nature of nestin-positive neurons may shed light on the cause and pathogenesis of the associated glioneuronal tumors and the accompanying chronic seizures.

Adolescent↗

PubMed2000

Malignant transformation of a dysembryoplastic neuroepithelial tumor. Case report.

A 29-year-old man presented in 1984 with a recent onset of partial seizures marked by speech arrest. Electroencephalography identified a left frontotemporal dysrhythmia. Computerized tomography (CT) scanning revealed a superficial hypodense nonenhancing lesion in the midleft frontal convexity, with some remodeling of the overlying skull. The patient was transferred to the London Health Sciences Centre for subtotal resection of what was diagnosed as a "fibrillary astrocytoma (microcystic)." He received no chemotherapy or radiation therapy and remained well for 11 years. The patient presented again in late 1995 with progressive seizure activity. Both CT and magnetic resonance imaging demonstrated a recurrent enhancing partly cystic lesion. A Grade IV astrocytoma was resected, and within the malignant tumor was a superficial area reminiscent of a dysembryoplastic neuroepithelial tumor (DNT). Data on the lesion that had been resected in 1984 were reviewed, and in retrospect the lesion was identified as a DNT of the complex form. It was bordered by cortical dysplasia and contained glial nodules, in addition to the specific glioneuronal element. The glial nodules were significant for moderate pleomorphism and rare mitotic figures. The Ki67 labeling index averaged 0.3% in the glial nodules and up to 4% focally. Cells were rarely Ki67 positive within the glioneuronal component. This case is the first documented example of malignant transformation of a DNT. It serves as a warning of the potential for malignant transformation in this entity, which has been traditionally accepted as benign. This warning may be especially warranted when confronted with complex forms of DNT. The completeness of resection in the benign state is of paramount importance.

Adult↗

PubMed1998

Case of the month: April 1998--30 year old male with perineal numbness.

A 30-year-old male presented with a 2 year progressive course of bowel and bladder dysfunction, mild leg weakness and sensory abnormalities in sacral dermatomes. MRI showed an intra-axial conus medullaris lesion which was excised and identified as a ganglioglioma. The case presents the typical clinical course and histopathology of this unusual lesion which carries a favorable prognosis after gross total removal. Preoperative neurological function in such patients is highly predictive of post-operative outcome.

Adult↗

PubMed1997

Nestin expression in reactive astrocytes following focal cerebral ischemia in rats.

During central nervous system (CNS) development, intermediate filaments are subjected to a sequential remodelling process. Nestin is a distinct intermediate filament which is transiently expressed in proliferating neuroepithelial stem cells during the neurulation stage of development. Nestin re-expression in the adult rat was studied following transient (2 h) middle cerebral artery occlusion. Seven days after the ischemic insult, nestin reactive astrocytes were found in the border zone surrounding cerebral infarction. Nestin immunoreactivity delineated a zone between infarction and the surrounding intact cerebral parenchyma. In situ hybridization for nestin mRNA showed early changes in small cells in the surround of the ischemic lesion. These results with nestin, along with other stem cell markers expressed by reactive astrocytes, suggest an embryonic reversion of the mature cytoskeleton as a response of astrocytes to cerebral injury.

Animals↗

PubMed1996

Association of pleomorphic xanthoastrocytoma with cortical dysplasia and neuronal tumors. A report of three cases.

BACKGROUND: Several recent publications indicate that pleomorphic xanthoastrocytoma (PXA) may occasionally express ganglionic cell differentiation, linking this type of tumor to other benign, mixed glioneuronal neoplasms. Furthermore, ganglionic tumors and less frequently some benign glial tumors in the central nervous system, could be associated with a variety of mild developmental abnormalities of the cerebral cortex that are classified under the broad term cortical dysplasia. The association of cortical dysplasia with PXA and a neuronal pattern of differentiation has not been reported previously. METHODS: The authors present clinical, radiologic, immunohistochemical, and ultrastructural findings in three patients with cortical dysplasia. The cortical dysplasia was continuous with PXA, displaying an additional component of neuronal cell differentiation. RESULTS: The ages of the patients were 23, 47, and 52 years. Resection of the tumors was predated by temporal lobe seizures by 6 years in 1 patient and by more than 30 years in the others. In all 3 cases, radiologic studies conducted 3-6 years before surgery showed either no abnormality or lesions that were initially nonprogressing. CONCLUSIONS: The longstanding clinical history of seizures and the existence of radiologically documented dormant lesions several years before tumor removal both suggest that PXA in these patients very likely developed in benign hamartomatous cortical lesions or in preexisting cortical dysplasia. The authors' findings, along with the consistent occurrence of PXA in the gray matter in the majority of the reported cases, indicate that these tumors may originate either from a subclass of astrocytes histogenetically and topographically associated with neurons or from multipotential neuroectodermal precursor cells common to neurons and astrocytes.

Adult↗

PubMed1994

Cellular radiosensitivity and DNA damage in primary human fibroblasts.

PURPOSE: To evaluate the relationship between radiation-induced cell survival and DNA damage in primary human fibroblasts to decide whether the initial or residual DNA damage levels are the more predictive of normal tissue cellular radiosensitivity. METHODS AND MATERIALS: Five primary human nonsyndromic and two primary ataxia telangiectasia fibroblast strains grown in monolayer were studied. Cell survival was assessed by clonogenic assay. Irradiation was given at high dose rate (HDR) 1-2 Gy/min. DNA damage was measured in stationary phase cells and expressed as fraction released from the well by pulsed-field gel electrophoresis (PFGE). For initial damage, cells were embedded in agarose and irradiated at HDR on ice. Residual DNA damage was measured in monolayer by allowing a 4-h repair period after HDR irradiation. RESULTS: Following HDR irradiation, cell survival varied between SF2 0.025 to 0.23. Measurement of initial DNA damage demonstrated linear induction up to 30 Gy, with small differences in the slope of the dose-response curve between strains. No correlation between cell survival and initial damage was found. Residual damage increased linearly up to 80 Gy with a variation in slope by a factor of 3.2. Cell survival correlated with the slope of the dose-response curves for residual damage of the different strains (p = 0.003). CONCLUSION: The relationship between radiation-induced cell survival and DNA damage in primary human fibroblasts of differing radiosensitivity is closest with the amount of DNA damage remaining after repair. If assays of DNA damage are to be used as predictors of normal tissue response to radiation, residual DNA damage provides the most likely correlation with cell survival.

Cell Survival↗

PubMed1981