Biomedical subjects

S K Shankar

Publications and source records attributed to S K Shankar.

At least 55 records · Page 3Linked to original sources

PubMed2001

Neuropsychiatric perspectives from nineteenth-century India: the diaries of Dr Charles I. Smith.

The history of disease contributes to a better understanding of the growth of ideas in medicine. The colonial period was marked by a rapid increase in the variety of diseases that were known to European practitioners. We have studied the diary of Dr Charles Smith who worked in Bangalore in the nineteenth century. We feel that some of his descriptions tally with later accounts of cysticercosis. He also comments on a wide range of behavioural symptoms, and attempts to correlate neuropathological observations to these. This neuropsychiatric perspective was prominent in the nineteenth century. Infective causes of psychiatric disorders are once again considered important; this account highlights the fact that similar ideas were prevalent in British India, even 150 years ago. In addition, Dr Smith's comments describe the social mileu of 'western' medicine in India in the early colonial period.

Colonialism↗

PubMed2001

Intracranial haemorrhage resulting from unsuspected choriocarcinoma metastasis.

A retrospective analysis of clinicopathological data of 10 patients with clinically unsuspected cerebral metastatic choriocarcinoma was carried out. All patients were young adult females. History of preceding pregnancy/abortion was forthcoming in 5 cases but none had a prior history of abnormal gestation. Features of raised intracranial tension followed by hemiparesis were the commonest presenting symptoms. A clinicoradiologic diagnosis of intracerebral haemorrhagic mass, either primary or secondary to tumour bleed, cortico-venous thrombosis or arteriovenous malformation, was entertained in 8 out of 10 cases. In other two cases, ring enhancing lesions prompted the diagnosis of granulomatous masses. Eight patients were operated upon, of whom two died after short hospital stay, and were autopsied. All had haemorrhagic masses noted at surgery/autopsy. Accurate diagnosis of metastatic choriocarcinoma was established only by histologic examination of these haemorrhages. This report emphasizes the importance of considering metastatic choriocarcinoma as an important differential diagnosis of haemorrhagic intracerebral lesions in women of child bearing age group. Measurement of serum/CSF level of HCG in suspected cases helps to implement early therapy. The diagnostic value of histopathologic examination of surgically resected blood clots in determining aetiology of intracerebral haemorrhagic masses is highlighted.

Adolescent↗

PubMed2001

Vasculitic neuropathy in HIV infection: a clinicopathological study.

Vasculitis causing peripheral neuropathy may be the first sign of HIV infection. We report four such cases in whom the onset of peripheral neuropathy led to the detection of HIV infection. Two patients presented with features of mononeuritis multiplex, while the other two had a lumbosacral polyradiculopathy. A prior history of blood transfusion was forthcoming in one of the patients. Sural nerve biopsies in all the four cases and the muscle biopsy in two, histologically showed evidence of vasculitis. Immunohistochemically, the viral antigen was not demonstrable in any of the biopsies, but on electron microscope, virus-like particles were identifiable in the Schwann cell cytoplasm and the perivascular macrophages in one case. To the best of our knowledge, this is the only report that has documented the virus in the Schwann cells as well as the perivascular macrophages lending credence to the fact that these viruses are neurotropic as well as lymphotropic. Immunoglobulin deposits were not demonstrable in any of the cases, suggesting that direct viral invasion may have a role in the pathogenesis of peripheral nerve vasculitis.

Adult↗

PubMed2000

Expression of p67 (Munc-18) in adult human brain and neuroectodermal tumors of human central nervous system.

p67 (Munc-18), is a neuron-specific protein of 67 kDa, known for its ability to bind with syntaxin and also to copurify with neuronal cdc2-like kinase. Earlier, in situ hybridization and immunocytochemical analysis of rat trigeminal ganglion and hippocampal cells demonstrated the specific localization of p67 in nerve cells and its rich distribution in axons. In the present study, we have looked for p67 expression in normal human brain and various neuroectodermal tumors. Immunohistochemical and Western immunoblot analysis of normal human brain tissue using antibodies against the N- and C-termini of p67 demonstrated the specific localization of this protein in postmitotic neurons but not in glia. Among neuroectodermal tumors, expression of p67 was observed in 100% of the tumors of neuronal origin studied, especially in the mature neuronal cell population of these tumors. Western immunoblot analysis of non-neuronal neuroectodermal tumors failed to reveal the expression of this protein in majority of cases. However, in gliomas and meningiomas, mild cytoplasmic immunohistochemical staining of neoplastic cells was noted in 64.7% and 25% of cases, respectively. Observed mild immunohistochemical staining of these tumors could be due to immunoreactivity to low molecular weight degraded products of p67, as seen on Western blot. The findings suggest that p67, by virtue of its ability to be expressed in postmitotic neurons of adult human brain and in tumors of neuronal origin, may serve as a molecular tool to understand the growth and differentiation of the nervous system in general.

Adult↗

PubMed2000

Pathology of Madras type of motor neuron disease (MMND)--a histological and immunohistochemical study.

A neuropathological report of Madras type of motor neuron disease (MMND) is presented and the differences from other forms of MND are discussed. An 18-year-old girl presented with nerve deafness and slowly progressive bulbo-spinal muscular atrophy, characteristic of MMND. Post-mortem examination of the spinal cord showed a severe loss of anterior horn cells, prominent dilatation of vessels, diffuse, but sparse sprinkling of microglial cells and lymphocytes, and demyelination and sclerosis of the ventrolateral columns. Neuronal depletion and marked gliosis was noted in the cochlear nucleus on both sides, while other bulbar motor nuclei were also involved. The cochlear nerve showed demyelination and axonal loss. Trigeminal and vestibular ganglia revealed features of ganglionitis. The possibility of an inflammatory aetiology for MMND needs to be considered.

Adolescent↗

PubMed2000

Giant intramedullary teratoma in an infant.

Teratomas are uncommon tumors of the nervous system, the commonest site being the pineal region. Spinal teratomas are very rare apart from the sacrococcygeal variety. The authors report the occurrence of an intramedullary teratoma in an infant. The clinical features, imaging studies and the pathology are discussed. In addition the literature is also reviewed.

Humans↗

PubMed2000

Centronuclear myopathy--morphological relation to developing human skeletal muscle: a clinicopathological evaluation.

Centronuclear myopathy (CNM), an uncommon condition, is one of the congenital myopathies. It is believed to arise as a result of maturational arrest, with persistence of myotubes postnatally. However, denervation being the basic disease process and its possible influence on central nervous system causing defect in nuclear migration has also been postulated. Keeping in view these existing controversies, we have studied 17 cases of CNM (neonatal - 1, childhood - 13, adulthood - 3) during the last twelve and a half years. Diagnosis was based on histological and enzyme histochemical findings of muscle biopsy along with clinical data. Ultrastructural characterstics of muscle have been studied in 10 cases. The affected muscle fibres showed a central nucleus (40-99%) with perinuclear halo. Type I fibre predominance with hypoplasia was consistently seen. Fibre type disproportion was noticed in 7 cases. The neonatal form revealed dense oxidative enzyme reaction product in the centre. The morphological features of CNM were compared with foetal skeletal muscles obtained at gestational ages ranging from 9 weeks - 36 weeks (n = 18). In the severe neonatal form th myofibres resembled the foetal myotubes. In the less severe childhood and adult form of CNM, aberrant organization of cytoskeletal network might have played a pathogenetic role in causing the disease.

Adolescent↗

PubMed2000

Intramedullary spinal epidermoid cyst.

Intramedullary epidermoid cysts of the spinal cord are rare tumours, especially those not associated with spinal dysraphism. Around 50 cases have been reported in the literature. Of these, only seven cases have had magnetic resonance imaging studies. We report two cases of spinal intramedullary epidermoid cysts with MR imaging. Both were not associated with spina bifida. In one patient the tumour was located at D4 vertebral level, while in other within the conus medullaris. The clinical features, MR imaging characteristics and surgical treatment of such rare intramedullary benign tumours are discussed, and the relevant literature reviewed.

Adolescent↗

PubMed2000

Profile of neurologic disorders associated with HIV/AIDS from Bangalore, south India (1989-96).

One hundred patients (95 males, 5 females, mean age at presentation 31.6 +/- 9.4 yr) with various neurological disorders associated with HIV infection during 1989-1996 were evaluated at NIMHANS, Bangalore. Eighty patients belonged to group I associated with opportunistic neuroinfections and 20 to group II--non infectious neurological disorders. Cryptococcal meningitis either alone (n = 31) or associated with tuberculous meningitis (n = 6) was the most common (46.3%) followed by neurotuberculosis either alone (n = 24) or with cerebral toxoplasmosis (n = 4) accounting for 35 per cent. Other opportunistic neuroinfections included cerebral toxoplasmosis, herpes zoster, fulminant pyogenic meningitis and neurosyphilis. Clinical characteristics, diagnostic clues, their laboratory and radiological profiles and problems encountered in diagnosis and management of these opportunistic infections are highlighted. In group II (19 males and one female; mean age of 32.6 +/- 9.4 yr), two patients had cortical dementia, three acute brain stem involvement, two epilepsy and one had features suggestive of progressive multifocal leukoencephalopathy. Two patients of group I during follow up developed cortical dementia. Six had peripheral nervous system involvement similar to Guillain-Barre syndrome. Sixty six patients (63 of group I and 3 of group II) progressed to AIDS, 33 patients from group I and one patient from group II succumbed to the disease. With the rapid increase in the incidence of HIV/AIDS and an increase in the neurological manifestations of HIV/AIDS it is important to recognise the magnitude of the problem for health planning in India.

AIDS-Related Opportunistic Infections↗

PubMed2000

Primary angiitis of CNS : neuropathological study of three autopsied cases with brief review of literature.

Primary angiitis of CNS(PACNS) or granulomatous angiitis of CNS is a rare inflammatory disease of small blood vessels mostly confined to the CNS. The clinical and pathological features of 3 autopsied cases are described. Clinically all the three PACNS patients were young males, age ranging from 19 to 31 years. All presented with varied neurological manifestations. There was no evidence of systemic disease in any of the cases. The ESR was normal and CSF analysis showed chronic meningitic pattern. The cerebral angiogram in one case was normal and the CT scan done in another case showed multiple intracerebral haematoma due to vasculitis. Brain biopsy was not done. Diagnosis was made at post-mortem examination. Histology showed characteristic but variable degree of granulomatous and non-granulomatous angiitis of small vessels. Venulitis with parenchymal haemorrhages was the predominant feature and in one case phlebitis with thrombosis was noted. Since the disease responds to steroids and immunosuppressive therapy, establishing antemortem diagnosis is important. In view of the association of angiitis of CNS with bacteria and viral infections, their role in the evolution of the disease needs to be investigated.

Adolescent↗

PubMed1999

Oral immunisation of mice with live Japanese encephalitis virus induces a protective immune response.

This study was undertaken to evaluate the efficacy of oral immunisation of mice with live Japanese encephalitis virus (JEV). Swiss albino mice were immunised with JEV by the peroral (p.o.), intraperitoneal (i.p.) and the subcutaneous (s.c.) routes on days 0, 7 and 14 using either mouse brain derived immunogen (MBDI) or cell culture derived immunogen (CCDI). Oral immunisation of mice evoked high anti-JEV antibody titres by ELISA (Geometric mean titres of 5065 with CCDI and 8854 with MBDI). Moreover, the orally immunised mice showed 76.7% protection with MBDI and 70% with CCDI against intracerebral challenge with a lethal dose of JEV. This study demonstrates for the first time that oral immunisation of mice with live JEV generates a brisk, protective immune response. The results of this study suggest that oral immunisation with JEV holds promise for the future.

Administration, Oral↗

PubMed1999

Benign triton tumor of the trigeminal nerve.

Benign triton tumor (neuromuscular hamartoma) is a rare tumor of the peripheral nerves, comprising mature neural and striated muscle elements. We report the third case, according to the literature, of a benign triton tumor affecting the Vth cranial nerve in a 4-year-old male child. The tumor was seen to involve the mandibular division of the trigeminal nerve in the infratemporal fossa and extend intracranially by eroding the base of middle cranial fossa. The mass was totally excised. In the tumor, bundles of axons intermingling with fascicles of relatively mature skeletal muscle were found. This type of hamartomatous lesions of neuroectodermal-mesenchymal origin could have arisen as the result of incorporation of mesenchymal tissue into nerve sheaths during embryogenesis or aberrant differentiation of neuroectodermal component into mesenchymal elements.

Child, Preschool↗

PubMed1999

Cavernous-venous malformation of brain stem--report of a case and review of literature.

BACKGROUND: Because of improved imaging techniques, the association of cavernous and venous malformations is now being seen more often in neurosurgical practice. However, only a few cases have been subjected to surgery. Surgical excision of the cavernous malformation, sparing the venous component, has been the method of choice advocated by most authors. This, however, is not possible when the components are intimately associated with each other. It thus becomes important to predict the surgical outcome in such lesions, especially when they are located in an eloquent area. A surgically excised case of cavernous-venous malformation in the dorsal pontomedullary region is presented here; the histology confirmed the intimate association of both components. The relevant literature is also discussed. CASE DESCRIPTION: This 20-year-old male presented with episodic vomiting, giddiness, and persistent cerebellar signs over a six-year period. Neuroimaging studies-computed tomography scan/magnetic resonance imaging (CT/MRI) were suggestive of a cavernous malformation. MRI also showed a draining vein close to the lesion. Following total excision, histopathology confirmed the intimate association of both cavernous and venous malformations. The patient made an uneventful recovery. MRI at follow up confirmed total excision. CONCLUSIONS: The presence of venous channels draining into a lesion that otherwise appears to be a cavernous malformation may indicate an intimately associated venous component. Selective surgical excision of the cavernous component may be difficult in such cases. Surgical outcome, though favorable in this case, will be difficult to comment upon unless more such cases are reported. This may be of greater significance in lesions located in eloquent areas.

Adult↗

PubMed1999

Diagnostic efficacy of stereotactic biopsies in intracranial tuberculomas.

BACKGROUND: Stereotactic biopsies for diagnosing intracranial tuberculomas are often reported to be inconclusive, being confirmatory in only 28% of cases. We analyzed the role and diagnostic efficacy of stereotactic biopsies in the management of intracranial tuberculomas. METHODS: Twenty patients diagnosed with intracranial tuberculomas based on neuroimaging procedures underwent computerized tomography (CT) guided stereotactic biopsies for histological confirmation. In 10 patients (Group A), biopsies were obtained from the center of the lesion; in the other 10 (Group B), biopsies were obtained from both the enhancing rim and the isodense center and examined separately. The tissues were processed for paraffin sections and hematoxylin eosin staining. In addition, in the first five patients a squash smear from a small portion of the biopsy was prepared, and the cytological features of the cells were examined. All the patients received antitubercular medication and CT scans were repeated 4 months posttreatment. RESULTS: Histopathological features of the paraffin sections in 17 patients (Group A: 8, Group B: 9) were diagnostic of tuberculoma, whereas the other three revealed only chronic nonspecific inflammation. Based on the cytological features in squash smears, diagnosis could be made in one of five. In two, although the smear was not diagnostic, the histological section from the same specimen confirmed the tuberculous pathology. There was no procedural morbidity or mortality. One patient had a small asymptomatic hematoma at the biopsy site. Three patients died during the follow-up period, due to secondary complications of tuberculosis. Repeat CT scans during follow-up after antituberculous treatment confirmed the reduction in the size of the lesion in 15/17 patients. CONCLUSION: The high positive yield of stereotactic biopsies in diagnosing tuberculomas argues for their inclusion in the management protocol for tuberculous mass lesions.

Biopsy↗

PubMed1999

Solitary olfactory groove schwannoma: case report with review of the literature.

A 45-year-old man presented with headaches of 6 months' duration and generalized seizures in a cluster 2 days prior to admission. Examination revealed bilateral papilloedema and no focal deficits. CT scan showed an isodense enhancing mass lesion in the right frontobasal region with perilesional edema. Bifrontal craniotomy (with total excision of the tumor) revealed a tumor in the region of the right olfactory groove attached to the cribriform plate. Histopathological examination disclosed it to be a hyalinised schwannoma. Solitary schwannomas arising from the olfactory groove are extremely rare. Only six other cases have been reported so far. The presentation. CT scan findings and histogenesis of the tumor are discussed along with a review of the literature.

Brain Neoplasms↗

PubMed1998

Thiol oxidation and loss of mitochondrial complex I precede excitatory amino acid-mediated neurodegeneration.

Human ingestion of "chickling peas" from the plant Lathyrus sativus, which contains an excitatory amino acid, L-BOAA (L-beta-N-oxalylamino-L-alanine), leads to a progressive corticospinal neurodegenerative disorder, neurolathyrism. Exposure to L-BOAA, but not its optical enantiomer D-BOAA, causes mitochondrial dysfunction as evidenced by loss of complex I activity in vitro in male mouse brain slices and in vivo in selected regions of mouse CNS (lumbosacral cord and motor cortex). Loss of complex I activity in lumbosacral cord after L-BOAA administration to mice was accompanied by concurrent loss of glutathione. The inhibited complex I activity in mitochondria isolated from lumbosacral cord of animals treated with L-BOAA rebounded after incubation with the thiol-reducing agent dithiothreitol, indicating that oxidation of protein thiols to disulfides was responsible for enzyme inhibition. The inhibition of complex I could be abolished by pretreatment with antioxidant thiols such as glutathione ester and alpha-lipoic acid. Chronic treatment of male mice, but not female mice, with L-BOAA resulted in loss of complex I activity and vacuolation and dendritic swelling of neurons in the motor cortex and lumbar cord, paralleling the regionality of the aforementioned biochemical effects on CNS mitochondria. These results support the view that thiol oxidation and concomitant mitochondrial dysfunction (also implicated in other neurodegenerative disorders), occurring downstream of glutamate receptor activation by L-BOAA, are primary events leading to neurodegeneration. Maintenance of protein thiol homeostasis by thiol delivery agents could potentially offer protection against excitotoxic insults such as those seen with L-BOAA.

Amino Acids, Diamino↗

PubMed1998

Acute thyrotoxic neuropathy--Basedow's paraplegia revisited.

A forty seven year old woman with previously undetected goitre, developed thyroid storm in the immediate postoperative period. Forty eight hours after undergoing nephrolithotomy for renal calculus, she was noted to have flaccid areflexic quadriparesis, most marked in the lower limbs. Electrophysiologic studies revealed evidence of an asymmetric, mixed axonal and demyelinating, motor-sensory peripheral neuropathy. Ultrastructure of the sural nerve showed predominant abnormalities in the mitochondria and cytoskeletal elements compatible with thyrotoxicosis. Treatment of thyrotoxicosis coincided with recovery of symptoms. We believe that thyrotoxicosis precipitated an acute polyneuropathy the ultrastructure of which is being described for the first time.

Acute Disease↗

PubMed1998

Low numbers and no loss of melanized nigral neurons with increasing age in normal human brains from India.

The prevalence of Parkinson's disease (PD) is higher in whites than in nonwhites and it increases with advancing age. The pathological hallmarks of PD are loss of pigmented neurons in the substantia nigra pars compacta (SNpc) and presence of Lewy bodies. With increasing age, a similar loss of pigmented neurons in the SNpc has been reported. Hence, age and race possibly play a role in the pathogenesis of PD. The objectives of this study were to count the number of melanized neurons in the SNpc in normal human brains from India and study the change in neuronal count with advancing age and to compare the neuronal counts from this Indian population with counts reported in normal brains from the United Kingdom. Melanized neurons in the SNpc were counted in 84 normal human brains (age range, 5-84 years) in a single 7-microm section at the level of emergence of the oculomotor nerve. In the brains from India, there was no loss of melanized nigral neurons with advancing age. The absolute number of these melanized neurons was about 40% lower than the brains from UK. Despite a low number of melanized nigral neurons in the brains from India, individuals function normally and have dopamine levels comparable with their Western counterparts, suggesting that it is not the absolute number of melanized nigral neurons but the percent loss of nigral neurons that results in dopaminergic deficiency in PD. There is no significant loss of pigmented nigral neurons with age, suggesting that the loss seen in PD is exclusively due to the disease process itself. Indians have a lower prevalence of PD despite having a low count of melanized nigral neurons, suggesting that better protective mechanisms may be present in the Indians to prevent the loss of nigral neurons.

Adolescent↗