PubMed Health⌕ Search

Biomedical subjects

A K Mahapatra

Publications and source records attributed to A K Mahapatra.

At least 109 records · Page 6Linked to original sources
PubMed1998

The expression of nitric oxide synthases in human brain tumours and peritumoral areas.

Nitric oxide, a potent signalling molecule produced from L-arginine by nitric oxide synthase (NOS), has been implicated in diverse pathophysiological processes. Many characteristics of malignant tumours such as increased vascular permeability, vasodilation, neovascularisation and free radical injury to the tumour and adjacent normal tissues are believed to be mediated by nitric oxide. While NOS expression has been demonstrated in brain tumours, no equivalent studies have yet been reported on the adjacent peritumoral brain region. The present study examined the pattern of NOS expression in the human tumour and peritumoral brain areas. Biopsies were obtained from eight patients (six gliomas, one each of meningioma and metastatic adenocarcinoma) from three areas: tumour, peritumoral, and apparently 'normal' adjacent brain tissue. Immunohistochemical staining was performed for three isoforms of NOS: brain NOS (BNOS), endothelial NOS (ENOS) and macrophage-specific NOS (MacNOS). Except for glioblastoma multiforme and metastatic adenocarcinoma, the tumour cells expressed all three NOS isoforms. In four tumours, there was a demonstrable gradient of ENOS expression falling away from the tumour. In three gliomas, many glial cells were intensely labelled with BNOS. This labelling decreased in the peritumoral tissues. In four tumours, cells (presumably lymphocytes, and CD 45 positive macrophages) were labelled intensely with MacNOS in and around the blood vessels. These results suggest that nitric oxide is produced in the tumour cells and endothelium of tumour vasculature, while occasionally glial cells may also be induced to produce it. The possible role of nitric oxide in the production of peritumoral oedema is discussed.

Adenocarcinoma↗
PubMed1998

Genetic alterations in brain tumors identified by RAPD analysis.

We report the utility of random amplified polymorphic DNA (RAPD) analysis for identifying subtle genomic alterations in meningiomas and gliomas by comparing the DNA band profile of tumor vis-à-vis its constitutional counterpart. Twenty out of the 29 decanucleotide GC-rich random primers utilized for the RAPD analysis of meningiomas revealed alteration(s) in the tumor genome. In gliomas, changes were detected by 16 of the 18 primers. While all the seven meningioma samples exhibited alterations in tumor DNA, changes were evident in 21 of the 24 glioma cases. These alterations in tumor DNA included the loss of a normal band, appearance of a new band and amplification of a pre-existing band. Many primers detected more than one alterations in a given tumor. Our approach, which covers the range from 0.4 to 2 kb, besides detecting a significant number of changes in a spectrum of brain tumors, complements existing DNA fingerprinting methods, such as microsatellite mapping (less than 0.4 kb) and Southern blotting (over 2 kb), for detecting genetic alterations in tumors.

Brain Neoplasms↗
PubMed1998

Medullomyoblastoma. A rare cerebellar tumour in children.

Seven patients between the ages of 3 and 24 years were admitted to our hospital in the last 28 years who had a histological diagnosis of medullomyoblastoma. These patients presented with classic symptoms of a posterior fossa midline mass associated with evidence of raised ICP. A CT scan in each patient revealed a uniformly high-attenuating tumour in the posterior fossa with gross hydrocephalus. In all seven patients a ventriculoperitoneal shunt was placed prior to definitive surgery. Radical tumour excision was carried out in all cases 3-5 days after CSF diversion. The histological diagnosis was made on H&E-stained slides. In two cases each, the tumour tissue was subjected to electron microscopy and immunohistochemical studies. Six of the seven patients survived the operation. One patient died 21 days after surgery as a result of shunt block and shunt infection. All surviving patients received cranial and spinal radiation 2-4 weeks after surgery, and also chemotherapy. The cranial radiation dose ranged from 4500 to 5000 rad, while the spinal radiation dose was limited to 1500 rad. Patients were followed up carefully. Three patients died within 6 months, and the remaining three between 2.5 and 3 years after surgery. None of the patients in our study survived longer than 3 years. One patient had developed paraplegia. This study highlights the details of an uncommon entity and reports the largest collection of such cases in the literature.

Adult↗
PubMed1998

The role of somatosensory evoked potentials in spinal dysraphism--do they have a prognostic significance?

Somatosensory evoked potentials (SEP) are not routinely used in spinal dysraphism. In this study 38 patients (29 children and 9 adults) with spinal dysraphism were prospectively studied with the objective of evaluating whether SEPs were a prognostic tool that could be used to predict clinical improvement after repair of a spinal dysraphic lesion. For all patients, preoperative SEP and postoperative SEP (within 1 week of operation) were recorded. Fifteen of these patients also had follow-up postoperative SEP recordings taken within 3 months of operation. A clinical examination was performed at the time of each SEP. Thirty patients had tethered cord, 12 had diastematomyelia and 15 had intra- and/or extradural tumours, which included lipomas and dermoid and epidermoid tumours. Twenty-one children and all adults had abnormal preoperative SEPs. Sixteen children and 4 adults had improved SEPs postoperatively. All these children and 2 of the 4 adults also experienced clinical improvement. Improvement in SEPs preceded clinical improvement in 12/20 patients. We observe that SEPs have a good prognostic value.

Adult↗
PubMed1998

Seizures following posterior fossa surgery.

A retrospective analysis of seizure incidence in 511 patients who underwent posterior possa operations via a suboccipital craniectomy with prophylactic anticonvulsant agents, was performed. Thirty patients (5.9%) experienced seizures within 2 weeks postoperatively. Their mean age was 15 years. Twenty patients had seizures within 3 h of operation; 24 patients had generalized tonic clonic seizures. Focal motor seizures with secondary generalization and simple focal motor seizures were recorded in three patients each. The incidence of postoperative seizures was highest in patients with acoustic schwanommas (9.09%) followed by those with medulloblastomas (8.54%) and astrocytomas (8.33%). The sitting position, associated with venous air embolism (VAE) and or pneumocephalus, was related to the occurrence (p = 0.001) of postoperative seizures. Seizures occurred in 24 patients out of 250 cases operated on in the sitting position compared with 3/170 and 3/91 in the prone and lateral positions, respectively. Intraoperatively significant VAE occurred in 10 out of 30 patients and postoperative computed tomography revealed pneunocephalus in 20 out of 30 patients. A higher percentage was found in patients with a preoperative ventriculoperitoneal shunt or intraoperative ventriculostomy (6.5%) than in those without (5.1%), but the difference was not statistically significant. In conclusion, seizures after posterior fossa surgery are a significant problem which is not reflected in the published literature. Our study highlights the significance of the sitting position in the causation of seizures after posterior fossa surgery.

Adolescent↗
PubMed1998

Hypothalamic hamartoma: report of a case with unusual histologic features.

A rare case of hypothalamic hamartoma with unusual radiologic and histopathological features is described, possibly the first of its type in English literature. A 1.5-year-old female child presented with precocious puberty. MR scan of the brain revealed a pedunculated hypothalamic mass, most of which was isointense with normal brain on T1- and T2-weighted images. However, a sizeable component of the lesion was hyperintense on T1-weighted images, suggestive of adipose tissue. Microscopically, the lesion was a hamartoma composed of an admixture of neuroectodermal elements, namely glial cells, neurons, and nerve bundles along with mesenchymal elements in the form of fibroadipose tissue.

Brain Diseases↗
PubMed1998

Correlation of ventricular size and transcranial Doppler findings before and after ventricular peritoneal shunt in patients with hydrocephalus: prospective study of 35 patients.

OBJECTIVE: To compare the cerebral blood flow velocity and pulsatility index in patients with hydrocephalus and to correlate the blood flow velocity to shunt function and size of ventricles in CT. METHODS: The study comprised 16 children and 19 adults, preoperative (transcranial Doppler, TCD) disclosed normal pulsatility index in six and raised pulsatility index in 29 patients. Preoperative CT showed moderate hydrocephalus in 32 and severe hydrocephalus in three patients. All patients had CT and TCD 36-48 hours after their shunt operation. RESULTS: A marked reduction in pulsatility index occurred postoperatively in 28 patients, all of them showed a significant decrease in ventricular size on postoperative CT done simultaneously. Mild or no reduction of pulsatility index was recorded in seven patients and none of them showed decreased ventricular size on postoperative CT. In two patients subsequent shunt blockage was accompanied by appropriate changes in both pulsatility index and CT, which reversed after successful shunt revision. CONCLUSION: Fall in pulsatility index correlated well with decrease in ventricle size. Thus TCD can be used as a simple, bedside test for the assessment of shunt function.

Adolescent↗
PubMed1998

Subdural empyema due to salmonella infection.

A case of a 6-month-old child with a Salmonella subdural empyema is reported. The causative organism was never suspected until the culture report was available. The child responded well to surgical drainage and antibiotic therapy.

Adolescent↗
PubMed1997

Loss of heterozygosity of a locus on 17p13.3, independent of p53, is associated with higher grades of astrocytic tumours.

Amongst the human astrocytic tumours, the commonest of primary brain tumours, the clinical outcome of astrocytoma (AS) is significantly better than anaplastic astrocytoma (AA) and glioblastoma multiforme (GBM). Often, low grade tumours can progress to or recur with a more malignant phenotype. Recent loss of heterozygosity (LOH) reports suspect the involvement of a tumour suppressor gene, different from p53, in the 17p13.3 region of the human chromosome. However, the effect of LOH of 17p13.3 region on tumour histology at presentation and prognosis is as yet undefined. As a first step to define the role of this putative oncogene in astrocytic tumour progression, we correlated the LOH of a locus, D17S379, in 17p13.3 region and the p53 locus in 17p13.1 region with the histopathology of astrocytic tumours by PCR based microsatellite and restriction fragment length polymorphism of DNA extracted from microdissected paraffin sections of 45 astrocytic tumours of different histopathological grades. LOH of D17S379 was significantly associated (P=0.02) with AA and GBM (high grade malignancy), while no such preferential association was found with LOH of p53. There were no mutations in the exons 5 to 9 of p53 gene in the five tumours with LOH of D17S379 but not of p53 region. In a case of AA with a heterogenous microscopic appearance, heterozygosity of D17S379 was lost only in the area with a more malignant histology while both areas had no LOH or mutation of p53. A locus at the 17p13.3 region, independent of the p53 locus, is involved in a large subset of astrocytic tumours during transformation into a more malignant phenotype, and thus may be a link in the chain of genetic events occurring in astrocytic tumour progression.

Astrocytoma↗
PubMed1997

Solitary giant skull base schwannomas--report of four cases.

BACKGROUND: Solitary intracranial schwannomas not related to major nerves or neurofibromatosis as well as paranasal schwannomas are rare. Schwannomas simultaneously involving the paranasal sinuses and intracranial cavity are even rarer. METHODS: We report four cases of schwannomas simultaneously involving the intracranial cavity and paranasal sinuses. They were successfully managed by surgery. The literature on such tumors is reviewed. RESULTS: All patients were young adults; the male to female ratio was 1:3. In two patients, the tumor was predominantly intracranial with extension into the sphenoid and ethmoid sinuses, whereas in the other patients, the tumor was located predominantly in the paranasal sinuses and nasopharynx with intracranial extension. Radiologically, bone destruction was seen in three cases. The tumors were totally removed piecemeal with repair of the basal dura. Histopathologic examination confirmed the diagnosis of schwannoma in all four cases. Three patients are alive and well; one of them was reoperated for a recurrence. CONCLUSIONS: These tumors should be excised completely if possible. Radiologically, bone erosion or destruction are suggestive of malignancy but histopathology clinches the diagnosis. Therefore, drastic surgery should be avoided in these cases. Surgery is generally curative in these massive schwannomas.

Adolescent↗
PubMed1997

Unilateral meningeal thickening: a rare presentation of tuberculous meningitis.

A rare case of tuberculous meningitis (TBM) causing unilateral thickening of meninges, is described here. The 50 year old male is presented with hemicranial headache and unilateral multiple cranial nerve involvement without any long tract signs. Magnetic resonance imaging (MRI) scan including enhanced studies showed a hemicranial thickening of the meninges. Biopsy of the meninges revealed tuberculosis. The patient improved gradually on antitubercular treatment (ATT). Follow-up at 6 months revealed significant improvement in neurological status. Though tuberculous involvement of the central nervous system (CNS) is very common in India, hemicranial meningeal involvement has never been reported.

Antitubercular Agents↗
PubMed1997

Pituitary abscess: a series of six cases.

Pituitary abscess is a rare condition occurring in various age groups. Only about a hundred cases have been reported in the literature. We describe six cases that constitute 0.6% of all the pituitary lesions operated at this centre in the last 10 years. All the patients presented with visual symptoms, though systemic features of infection were present in only two cases. The abscess was seen in association with adenoma in two cases and Rathke's cleft cyst in one. One patient developed an abscess following surgery for pituitary adenoma. The offending organisms was fungal in two cases, mycobacterium in one, bacterial in one and two cultures were sterile. Preoperative diagnosis is difficult and a high degree of suspicion in ring enhancing lesions of the sella is required.

Abscess↗
PubMed1997

Cognitive function in younger type II diabetes.

OBJECTIVE: To examine central nervous system involvement as a possible complication of diabetes by performing a comprehensive neuropsychological evaluation of relatively young (age < 55 years) NIDDM patients and a group of control subjects. RESEARCH DESIGN AND METHODS: A cross-sectional comparative study of 28 patients, with duration of diabetes 5-18 years (mean +/- SD +/- 3.2 years), screened for acceptable glycemic control and absence of hypoglycemia on the day of examination, compared with 28 demographically similar, nondiabetic control subjects. Neuropsychometric tests performed were Mini-Mental Status Examination (MMSE), Neurobehavioral Cognitive Status Examination (NCSE), and P300 latencies (endogenous evoked potentials). RESULTS: Seven (25.0%) patients reported history suggestive of cognitive impairment during day-to-day activities, and 17 (60.7%) had distal symmetrical polyneuropathy. Average P300 latencies were significantly delayed among the diabetic patients compared with the control subjects (349.5 +/- 28.2 vs. 312.9 +/- 19.3 ms; t = 5.68, P < 0.001). Although there was no significant difference in MMSE scores, compared with control subjects significantly more patients had impairment in NCSE tests of attention (chi 2 = 7.38, P < 0.01), repetition (chi 2 = 4.073, P < 0.05), and memory (chi 2 = 5.83, P < 0.05), while there was no significant difference in tests of comprehension, naming, construction, and calculation. Duration of diabetes, HbA1c levels, and the presence of distal symmetrical polyneuropathy among patients each did not correlate with any of the parameters of cognitive function evaluated. Higher blood glucose levels during the electrophysiological testing were associated with less delay in P300 latencies among the patients. CONCLUSIONS: Central nervous system impairment, manifesting as mild impairments in certain cognitive skills, should be recognized as a possible complication of long-standing NIDDM, even in relatively younger individuals.

Adult↗
PubMed1996

Primary extramedullary orbital plasmacytoma in a child.

We describe a rare case of extramedullary plasmacytoma of the orbit in an 11-year-old boy. Immunoperoxidase staining of the tissue was positive for IgG, kappa chain and negative for lambda chain. Serum and urine electrophoresis showed no M spike. Systemic examination and bone marrow aspirate failed to show generalised involvement. The tumour was completely excised and radiotherapy given postoperatively.

Child↗
PubMed1996

Intracranial intraparenchymal schwannomas: a series of eight cases.

Intraparenchymal schwannomas of the CNS are extremely rare. Between 1979 and 1993 400 cases of intracranial schwannomas were operated on and among them were eight patients with intraparenchymal schwannomas comprising 2% of intracranial benign nerve sheath tumours. Four of them were located in the cerebral hemispheres and two each in the brain stem and in the cerebellum. In two cases, there was associated neurofibromatosis (NF-1 and NF-2, one case each). The age ranged from 6 months to 45 years with a male/female ratio of 3:1 and, surprisingly, six of them were in the left cerebral or cerebellar hemisphere.

Adolescent↗