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Biomedical subjects

C Sarkar

Publications and source records attributed to C Sarkar.

At least 109 records · Page 6Linked to original sources
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↗
PubMed1992

Idiopathic inflammatory myopathy: clinicopathological observations in the Indian population.

The present study attempts to investigate the pathological basis of the two clinically different forms of idiopathic inflammatory myopathy (IIM) namely, polymyositis (PM) and dermatomyositis (DM). Clinicopathological analysis of 73 cases showed that muscle fibre necrosis and regeneration were more frequent in PM than in DM, the latter being significantly so (P < 0.05). On the other hand, vasculitis was more associated with DM while perifascicular atrophy of the muscle fibres was confined to it. Vasculitis was present in eight cases. Its incidence in patients with myositis with systemic connective tissue disease (4/9) was significantly more than in other PM and DM patients (P < 0.01). An equally significant higher frequency of perimysial inflammatory infiltrate was also seen in the former as compared to the latter. Interestingly, idiopathic DM affected men as often as women and juvenile IIM affected boys more frequently than girls. A female predilection was noted in the remaining groups of IIM. These observations indicate that there may be some basic immunopathogenetic differences between polymyositis and dermatomyositis as well as between idiopathic PM/DM and that associated with systemic connective tissue diseases. Though the number of patients studied is small, the absence of female predilection in idiopathic DM and juvenile IIM may be peculiar to the IIM in the tropics.

Adolescent↗
PubMed1992

Plasmacytoma of anterior maxilla mimicking periapical cyst.

An unusual case of plasmacytoma mimicking a large periapical cyst in the anterior maxilla is described. Of the involved teeth, 22 was discoloured and had an open, immature apex, a feature strongly suggestive of the lesion being of pulpal origin. The case was treated by a conservative endodontic approach, but failed to show any improvement. Apical surgery comprising complete enucleation of the cystic lesion and extraction of the involved tooth was carried out. The unexpected histopathological finding was a plasmacytoma.

Adult↗
PubMed1992

Dystrophin test in differential diagnosis of childhood muscular dystrophies.

Two cases of childhood muscular dystrophy are described. One of them had clinical features suggestive of Emery-Dreifuss muscular dystrophy and the other with some features of Prader-Willi syndrome, besides proximal muscle weakness. Muscle biopsy from both cases revealed a clear abnormality of dystrophin, and were diagnosed as having Duchenne muscular dystrophy (DMD) by immunofluorescence examination; that is, absent dystrophin at the membrane of the muscle fibers. The clinical spectrum of DMD-related myopathies and the importance of dystrophin testing in childhood muscular dystrophies is discussed.

Biopsy↗
PubMed1992

Ultrastructural study of mixed growth hormone & prolactin secreting pituitary adenomas.

An ultrastructural study was done on 15 mixed growth hormone (GH) and prolactin (PRL)-secreting pituitary adenomas surgically removed from acromegalic patients with hyper-prolactinaemia, in order to see whether the 2 hormones were present in the same cell or in different cells. Double labelling immunogold technique was used for simultaneous ultrastructural localization of GH and PRL. It was found that each neoplastic cell in these 15 tumours (30 to 50 cells were studied in each case) contained 4 populations of granules viz., (i) granules positive for only GH; (ii) granules positive for only PRL; (iii) granules positive for both GH and PRL; and (iv) granules negative for both GH and PRL (unlabelled). Though the relative percentage of these 4 types of granules varied from cell to cell even within the same tumour, the major population (49.9 to 96%) was constituted by the mixed granules showing labelling for both GH and PRL. Almost all the cells examined from each tumour appeared to be mammosomatotrophs. Thus, the study indicated that mammosomatotroph adenomas are perhaps more common among mixed GH and PRL--secreting pituitary adenomas than previously believed. It could be important to recognize these tumours from the therapeutic point of view.

Acromegaly↗
PubMed1992

Immunohistochemical, ultrastructural & immunoelectron microscopic study of glial fibrillary acidic protein in corpora amylacea.

Brain tissues from 10 patients (of non-neurological disease) were studied for the presence of corpora amylacea (CA) using light microscopy (LM), immunohistochemistry (IH) for localisation of glial fibrillary acidic protein (GFAP) and transmission electron microscopy (TEM). Immunoelectron microscopy (IEM) by post-embedding technique using colloidal gold was also performed in two of these patients for more precise localisation of GFAP. Three types of immunoreactivity were noted by IH under LM; some CA were completely negative for GFAP (type III), while others showed positivity, which was either diffuse (type I) or confined to the periphery (rim positivity-type II). TEM showed variable sizes in electron dense material in the centre associated with different amounts of glial filaments (GFs) at the periphery. Thus the different types of IH staining appeared to corroborate with the presence and amount of GFs in CA. The sensitive technique of IEM confirmed the presence of GFAP in all CA irrespective of their IH typing at LM. It is suggested that CA formation in astrocytes is associated with progressive fragmentation and disintegration of GFs with resulting increase in the accumulation of electron dense GFAP-negative material. As more and more of GFs get incorporated and disintegrated, it results in increase in the size of the CA. Thus, the present study clearly demonstrates that GFAP in the GFs contributes to the composition of CA.

Aged↗
PubMed1991

Fibrosarcoma of the scalp following postoperative radiotherapy for medulloblastoma.

A rare case of fibrosarcoma of the scalp following postoperative radiotherapy for medulloblastoma is reported. A review of similar cases in the literature was undertaken in an attempt to find a correlation between the dose of radiation, the length of the latent period, and the nature of the neoplasm. A significantly shorter latent period was found for sarcomas. No relationship was observed between the radiation dose and the latent period. The present case is unique in that the post-irradiation neoplasm (PIN) occurred in a predominantly extracranial site after treatment for a desmoplastic medullobastoma and had a remarkably short latent period.

Cerebellar Neoplasms↗
PubMed1991

Control of lymphocyte migration into brain: selective interactions of lymphocyte subpopulations with brain endothelium.

We have determined whether particular lymphocyte populations bind preferentially to cerebral endothelium, using adhesion assays and a new method for in situ staining of adherent lymphocytes. B cells bind more strongly than T cells, an effect enhanced by lymphocyte activation or endothelial cell stimulation with interferon-gamma (IFN-gamma) or tumour necrosis factor-alpha (TNF-alpha). This is not equated with levels of CD18 expression on the lymphocytes. CD8+ T cells bound more efficiently than CD4+ cells under all conditions. To determine whether there was a population of cells which selectively homes to the brain, we compared adhesion of cervical lymph nodes cells to brain endothelium, with adhesion of lymphocytes from other nodes. In 50% of the experiments there was significantly enhanced binding of activated cervical lymph cells to cerebral endothelium but not to control (aortic) endothelium. This effect was seen using both normal and IFN-gamma-activated endothelium. The explanation for this finding is that cervical lymph nodes frequently, but not invariably, contain higher proportions of CD8+ cells and B cells than other lymph nodes. These data imply that selective adhesion of lymphocytes to brain endothelium is related to the subpopulations involved and this may be reflected in the cell types seen in immunological lesions of the brain, and in the relative proportions of the subpopulations seen in cervical lymph nodes.

Animals↗
PubMed1990

Rosenthal fibres: an immunohistochemical, ultrastructural and immunoelectron microscopic study.

The nature of Rosenthal fibres (RF) was investigated in eight cases each of low-grade astrocytoma and reactive gliosis using immunohistochemical (IH) staining for glial fibrillary acidic protein (GFAP), electron microscopy (EM) and immunoelectron microscopy (IEM) by immunogold labelling technique. By IH under light microscopy (LM), three types of RF were seen, uniformly positive (type I), rim positive (type II) and completely negative (type III). EM showed variation in structural pattern of RF. Some RF contained large amount of glial filaments (GF) intermingled with RF while others with a large amount of electron dense material and less GF. Thus, the presence and amount of GF in RF appear to be responsible for the different types of IH staining under LM. IEM showed that all RF including the ones consisting of entirely amorphous material possess immunoreactivity for GFAP. It is suggested that RF formation is a two-stage process, starting with excessive accumulation of GF within astrocytic processes followed by their gradual alteration into electron-dense amorphous material under the influence of some unknown metabolic or other factors. The quantitative analysis of different types of RF suggests a difference in the rate of formation of RF in neoplastic and reactive conditions.

Astrocytoma↗
PubMed1990

Benign nerve sheath tumors: a light microscopic, electron microscopic and immunohistochemical study of 102 cases.

One hundred and two cases of benign nerve sheath tumors (NSTs) were studied with a combined approach using routine light microscopy (LM), immunohistochemistry (IH) for myelin basic protein (MBP) and S-100 protein as well as transmission electron microscopy (TEM) with the aim of obtaining greater insight into the true nature of these neoplasms, and also to establish the importance of IH and TEM in their diagnosis. Myelin basic protein was not identified in any of these tumors, whereas S-100 protein was positive to a variable degree in both schwannomas and neurofibromas. TEM revealed that Schwann cells predominated in tumors which were strongly positive for S-100 protein and appeared as schwannomas by LM. However, neurofibromas showing a variable patchy positivity for S-100 were composed of an admixture of Schwann cells, fibroblast-like cells and intermediate cells considered to be modified Schwann cells. Perineurial cells in typical form were not seen. It is concluded that all NSTs are basically of Schwann cell origin and that the intermediate cells and fibroblast-like cells are variants of Schwann cells. The different morphological appearances and biological behaviour of schwannomas and neurofibromas may be related to some other factors like micro-environment or genetic predisposition. Further, both IH, especially for S-100 protein, and TEM play an important role in establishing their diagnosis.

Cranial Nerve Neoplasms↗
PubMed1990

Xanthomatous change in tumours of glial origin.

Six patients with glial tumours showing xanthomatous change are reported here. Four patients in the series showed features of anaplastic (malignant) glioma or glioblastoma multiforme. In these patients, the astrocytic origin of the xanthomatous cells was confirmed by electron microscopy and immunohistochemistry using glial fibrillary acidic protein (GFAP). Of these, in one patient (no. 4) xanthomatous change was seen in an anaplastic (malignant) mixed glioma with significant ependymal component. Only one patient (no. 5) could be considered histologically as pleomorphic xanthoastrocytoma, but no clinical follow up was available. The value of immunohistochemical staining for GFAP in distinguishing gliomas with xanthomatous change from true xanthofibromas and xanthosarcomas was demonstrated in one patient (no. 6) in whom the glioblastomatous areas were GFAP positive but the xanthomatous areas were negative. This was therefore considered as a rare condition of glioblastoma with xanthosarcoma.

Astrocytoma↗