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C Sarkar

Publications and source records attributed to C Sarkar.

At least 19 recordsLinked to original sources
PubMed1996

c-myc oncogene expression and cell proliferation in mixed oligo-astrocytoma.

Mixed gliomas (oligo-astrocytomas) are brain tumours with an admixture of 2 different cell populations: astrocytes and oligodendroglia. On the basis of histological features and behaviour, these tumours are classified as low-grade mixed gliomas (MG) and malignant mixed gliomas (MMG). We have studied the relationship between c-myc protein expression and cellular proliferation in this class of tumours. Using antibody c-33 for c-myc and PC-10 for the proliferating cell nuclear antigen (PCNA), immunohistochemistry was performed on 14 MG and 9 MMG. PCNA was increased in MMG as compared to MG in both astrocytic and oligodendroglial areas. However, more c-myc-positive cells were seen only in the astrocyte areas of MMG. Analysis of the relationship of c-myc and PCNA suggests that the correlation of c-myc with cellular proliferation is dependent on tissue type and differentiation status.

Antibodies, Monoclonal↗
PubMed1996

A grading study of gliomas using computer aided malignancy classification and histologic morphometry.

Forty three cases of astrocytic tumors and mixed gliomas were studied with the aim of evaluating the reproducibility of the Kernohan grading system vis a vis (a) grading using computer-aided malignancy classifier TESTAST 268 and (b) grading by quantitative morphometric evaluation of the various histological parameters of TESTAST 268. These patients were then followed up for variable periods with a maximum of forty months. High inter and intra-observer variability were observed in the Kernohan grading system. TESTAST 268 was found to be simpler, rapid and more reproducible. However, one drawback observed of this system was that it did not completely eliminate inter-observer variability because there was still some subjectivity in assignment of the categorical values against the histological features. Morphometric evaluation of the semi-quantitative assignment values of the 4 histological variables in the TESTAST 268 classifier using Zeiss Morphomat-30 revealed a statistically significant difference between the clusters of the measured quantitative values. A repeat grading using TESTAST 268 and categorical assignment values of histological features derived from the absolute values obtained by morphometry resulted in complete elimination of inter-observer variability. Thus, this study highlights the importance of objectivisation using TESTAST 268 and histologic morphometry in the grading of gliomas. However, since this is a preliminary study on a small number of cases, no cut off values of these measurements have been proposed.

Adolescent↗
PubMed1995

Infrequent alteration of the c-myc gene in human glial tumours associated with increased numbers of c-myc positive cells.

Twenty five human glial tumours of different grades of malignancy were examined by Southern blotting and polymerase chain reaction (PCR) for alterations (rearrangements, amplification and deletions) in the c-myc gene. Number of c-myc positive cells per thousand cells were also counted in all the tumours after immunohistochemical staining for c-myc protein was done on fixed sections of the tumours. No tumours exhibited any amplification of the gene, as found by Southern blotting. One astrocytoma and one mixed glioma showed some rearrangements in the 3' end of the gene, as detected by Southern blotting and hydridization. These two tumours had higher number of c-myc positive cells than in other tumours of the same histopathological groups. Deletion in the first promoter region, as determined by PCR, was seen in only one astrocytoma. However, the number of c-myc positive cells in that tumour did not show any deviation from that found in other astrocytomas. In light of present literature, it is speculated that the 3' rearrangements may be the cause of increased number of c-myc immunopositive cells in those tumours by disrupting the 3' end of the gene leading to increased c-myc mRNA stability. Such a mechanism may play a part in small subset of glial and possibly other tumours.

Base Sequence↗
PubMed1995

A correlative study of in vivo and in vitro labeling index using bromodeoxyuridine in human brain tumors.

The labeling index (LI) of 216 cases of human brain tumors was determined by the immunohistochemical technique with monoclonal antibody to bromodeoxyuridine (BrdU). The proliferative potential of 110 cases was estimated using the intra-operative intravenous infusion of BrdU at a dose of 200 mg/sq m. In another 106 cases, the in vitro technique of incubating freshly resected tumor tissue fragments with 100 microM bromodeoxyuridine was used. The BrdU LI in these tumors was then correlated with the histological types and the data as determined by both the in vivo and in vitro BrdU incorporation were compared. The results indicate that although in vivo and in vitro techniques could possibly provide equivalent data in some histologic types, a clear statistically valid proof however is not apparent from this study.

Adolescent↗
PubMed1995

Primitive neuroectodermal tumor of maxilla in an adult.

Primitive neuroectodermal tumor is primarily a central nervous system tumor. These tumors are generally manifest in infancy or early childhood. The following article reports a rare case of primitive neuroectodermal tumor in posterior maxilla in an adult. Treatment for primitive neuroectodermal tumor in extracranial sites in adults is not clearly defined in the literature. This case was treated by combined chemotherapy followed by radiotherapy, which failed to cause regression of the lesion.

Adult↗
PubMed1994

Rearranged p53 gene with loss of normal allele in a low-grade nonrecurrent glioma.

We are studying the p53 gene profile in primary glial tumors by seeking alterations in the hybridization pattern of the tumor DNA probed with a p53 gene probe. This report documents a rearranged p53 gene with loss of the normal allele in a low-grade mixed glioma which has not recurred during 4-year follow-up. The tumor had a low 5-bromodeoxyuridine (BrdU)-labeling index and low AgNOR count. The p53 protein was not detected on immunochemical staining. To our knowledge, this is the first report of an altered p53 gene in a low-grade nonrecurrent glial tumor and highlights the presence of further checks and balances on the control of cell proliferation and other malignancy-associated phenotypes, even in an already-established tumor.

Alleles↗
PubMed1994

Cell culture studies on human nerve sheath tumors.

The main controversy about nerve sheath tumors (NSTs) has been their histogenesis. A Schwann cell origin has been proposed by many investigators for both schwannomas and neurofibromas. However Erlandson and Woodruff observed that while schwannomas appeared to be composed predominantly of Schwann cells, neurofibromas consisted of mainly perineurial cells. In addition, variable numbers of fibroblast-like cells and intermediate cells also have been reported in the 2 lesions. Whether these represent distinct cell types or variants of Schwann cells is still debatable. In an attempt to solve this controversy, the present study was undertaken to observe the morphology and the behaviour of these tumors in culture. These studies showed that all nerve sheath tumors are basically of Schwann cell origin and that intermediate cells and fibroblasts are variants of Schwann cell. Tissue culture studies done chiefly on schwannomas showed that the morphological features of schwannomas are preserved in 'in vitro culture' condition and therefore the difference between neurofibroma and schwannoma appears to be due to inherent differentiating property of the Schwann cells along with some environmental stimulus.

Adolescent↗
PubMed1994

Cushing's disease: pituitary imaging.

Fourteen patients with adrenocorticotropic hormone (ACTH)-dependent hypercortisolism underwent pituitary scanning with computed axial tomography (CT) and magnetic resonance imaging (MRI). Computed tomography revealed pituitary macroadenomas in two patients, pituitary hyperplasia in one and a suspicion of pituitary microadenoma in one. Thirteen patients underwent MRI. One with a macroadenoma diagnosed on CT did not undergo MRI. The MRI revealed a pituitary macroadenoma in one, microadenoma in three and hyperplasia in two cases. Magnetic resonance imaging following gadolinium diethylene triamine penta acetic acid (gd-DTPA) enhancement revealed four more pituitary microadenomas. All patients who had pituitary adenomas (micro and macro) and hyperplasia underwent trans-sphenoidal pituitary surgery. One of the two patients, who had an enlarged pituitary on imaging but no demonstrable adenoma, was found to have a microadenoma at surgery. Patients with ACTH-dependent hypercortisolism should undergo MRI of the pituitary gland to identify/localize corticotroph pituitary adenomas. The study should include gd-DTPA enhancement in cases where the scan is normal.

Adenoma↗
PubMed1994

Lymphocytic hypophysitis. Case report.

A case of lymphocytic hypophysitis is described in a patient presenting with panhypopituitarism 8 years after her last childbirth. The patient developed headache, vomiting, and diplopia (due to palsy of the right lateral rectus muscle) 7 months after delivery of her last baby. The diplopia disappeared after a few days with symptomatic treatment, and the headache and vomiting decreased in intensity with analgesic therapy. Eight years later the patient developed symptoms suggestive of hypoadrenalism, hypothyroidism, and amenorrhea. Investigations revealed panhypopituitarism with a pituitary mass lesion. Repeat evaluation 1 year later demonstrated no change in the size of the pituitary gland. The patient underwent transsphenoidal surgery with a provisional diagnosis of pituitary adenoma. Histological examination of the resected gland revealed evidence of lymphocytic hypophysitis. Symptoms suggestive of a pituitary mass lesion were noted during the peripartum period, but features of hypopituitarism developed much later. Such a long latent period has not been reported before. This report also highlights the fact that glandular enlargement may persist for many years after the onset of lymphocytic hypophysitis.

Adult↗
PubMed1994

Primary cerebellopontine angle choroid plexus papilloma: a case report and review of literature.

A case of primary choroid plexus papilloma of the cerebellopontine (CP) angle is described in a 28 years old man. He presented with hearing loss, right facial palsy and spastic quadriparesis (4/5). He also had markedly increased intracranial pressure. CT scan revealed a large high attenuating lesion in right CP angle with gross hydrocephalus. The patient was operated with the clinical and radiological diagnosis of right sided acoustic tumor with brainstem compression. Radical tumour excision was performed, seven days following VP shunt. Patient had immediate postoperative deterioration followed by a steady recovery. The possibility of a secretory choroid plexus papilloma is discussed.

Adult↗
PubMed1994

Solitary intracranial plasmacytoma of the skull base.

Two cases of extradural solitary plasmacytoma (SIP) with infiltration of the dura, destruction of the skull base, multiple cranial nerve palsies and proptosis are presented. The cases were treated aggressively with surgery and radiotherapy and showed no signs of progressing to multiple myeloma after 15 months and four and a half years respectively.

Adult↗
PubMed1993

A sequential cell kinetic study of meningioma cells in primary explant culture using bromodeoxyuridine.

The present study was undertaken to evaluate the sequential BrdU-LI at weekly intervals upto four weeks in 18 primary explant cultures of meningiomas. This revealed three distinct patterns of growth which could be arbitrarily defined as 'degenerating' (group I), 'proliferating' (group II) and 'adaptive' (group III) types. Interestingly two cases of malignant and two of recurrent meningiomas fell into the 'degenerating' group I pattern. The possible explanations for the observed relatively higher in vitro LI values compared to lower in vivo values as reported in the literature and the theoretical implications of the three distinct patterns of sequential LI values are discussed.

Adult↗
PubMed1993

A transmission and scanning electron microscopic study of tumoral and peritumoral microblood vessels in human gliomas.

The tumor microblood vessels (MBVs) of 25 cases of gliomas of varying grades were studied and compared with those in peritumoral region using both transmission and scanning electron microscopy (TEM and SEM). The TEM study revealed numerous villous projections with pinocytotic vesicles (PCVs) and large vacuoles (LVs) concentrated mainly at the luminal aspect in tumor MBVs which increased with increasing severity of edema. The peritumoral MBVs, in addition to showing some increase in villous projections on the luminal surface, also showed increased number of PCVs and LVs concentrated at the abluminal aspect with some of them even communicating with the extravascular space. The SEM study largely corroborated the TEM findings. The sites of formation of PCVs and LVs appeared as small pits or large craters on the luminal surface of the endothelial cells of tumor MBVs. We feel that the morphological evidence of increased permeability in tumor MBVs represents their role in the development of edema and that the occurrence of reverse pinocytosis in peritumoral MBVs is a distinct possibility which may be associated with resorption of edema fluid.

Astrocytoma↗
PubMed1993

In-vivo proliferative potential of primary human brain tumors; its correlation with histological classification and morphological features: I. Gliomas.

This study was undertaken to investigate in-vivo proliferative potential of neoplastic cells in 66 cases of gliomas of different histological types following peroperative intravenous infusion of bromodeoxyuridine (BrdU). Histological typing according to the recent modification of WHO classification did not often correlate with in-vivo cell kinetics. Among the different morphological features used for the classification, necrosis, mitosis, increased cell density and increased endothelial cell proliferation showed good correlation with tumor cell labelling index (LI) (p < 0.01-p < 0.001). A preliminary follow-up study of 36 cases for a period ranging from 9 to 36 mths suggested the possibility that higher in-vivo tumor cell LI might be associated with an early recurrence. Thus in vivo BrdU LI may supplement the histological classification of gliomas and together they may help in a better assessment of their growth rate, degree of malignancy and biological behaviour which in turn facilitate the planning of therapeutic management for individual cases.

Adolescent↗
PubMed1993

In-vivo proliferative potential of primary human brain tumors; its correlation with histological classification and morphological features: II. Nonglial tumors.

In-vivo cell kinetics study following peroperative intravenous infusion of bromodeoxyuridine (BrdU) was done in 10 cases of primitive neuroectodermal tumors (PNET) and 44 nonglial tumors of different histological types. The histological features usually regarded as indicators of aggressive behaviour were examined in these tumors and correlated with in-vivo labelling index (LI). In the case of meningiomas, increased cellularity, pleomorphism and mitosis had no correlation with LI. Benign non-recurrent meningiomas usually showed LI < or = 1% (mean 0.6 +/- 0.3%) whereas recurrent and malignant meningioma showed higher LI (mean 2.6 +/- 0.5% and 2.8 +/- 0.4% respectively). Follow-up study suggested that meningiomas having benign histological appearance with LI > 1% might have increased chance of recurrence. In cases of PNETs among different histological features, mitosis and differentiation seemed to be related to the biological behaviour. Astrocytic differentiation was associated with lower rate of proliferation. In pituitary adenomas different hormone producing and null cell adenomas showed similar low proliferative potential (0.6 +/- 0.3%). Benign nerve sheath tumors, craniopharyngioma and choroid plexus papilloma showed low in-vivo LI of less than 1%. Thus the present study revealed the inadequacies of routine histological examination in assessing the aggressiveness of the nonglial tumors, especially meningiomas. In-vivo LI may be a good supplement to histological diagnosis as well as helping to assess the prognosis and accordingly the management of individual cases.

Adolescent↗
PubMed1993

Morphological appearance, growth kinetics and glial fibrillary acidic protein (GFAP) expression in primary in vitro explant culture of astrocytic neoplasms.

Astrocytomas of different grades of malignancy were cultured as primary explant and their sequential growth pattern, glial fibrillary acidic protein (GFAP) expression and labelling index (LI) using bromodeoxyuridine (BrdU) were assessed and correlated with the grade of malignancy of the original tumor tissue. Low-grade astrocytomas showed patterns of growth that diverged from anaplastic astrocytomas and glioblastoma multiforme. The GFAP expression decreased with increasing time in culture in all astrocytomas irrespective of the grading. Maximum GFAP was, however, expressed in the morphologically well-differentiated stellate cells. Contrary to expectations, lower BrdU LI was observed in glioblastoma multiforme in comparison to low-grade astrocytomas, which suggests some unidentified mechanism of differentiation in vitro for astrocytomas of higher grade of malignancy. Hence, in contrast to reported literature on the prognostic value of studies on primary cultures, the present study cautions the extrapolation of the in vitro findings for astrocytomas.

Adolescent↗