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Biomedical subjects

A Chakrabarty

Publications and source records attributed to A Chakrabarty.

At least 37 records · Page 2Linked to original sources
PubMed2000

Temporal artery biopsy: is there any value in examining biopsies at multiple levels?

AIMS: To analyse the cost-effectiveness of three strategies for examining temporal artery biopsies based on data from cases examined over the past 10 years. METHODS: Of a total of 172 temporal artery biopsies, five were unsuitable for further analysis, 47 had already had levels cut, and 120 had levels cut as part of the study. All the biopsies were examined blind before and after levels. A tree with eventual diagnostic outcomes for different strategies was constructed and economic and sensitivity analyses performed. Welcan units were used to assess technical workload. RESULTS: Only one of the 132 initially normal cases and two of 14 diagnosed with periarterial lymphocytic infiltration (PALI) revealed giant cell arteritis after examining the tissue at multiple levels. Fifteen cases (8.9%) showed PALI not previously observed. The marginal cost for each extra case of giant cell arteritis detected was 83.5 Welcan units for a strategy of routine levels on all sections, and 21 Welcan units for a strategy of only cutting levels if PALI was present on the initial section. These costs were sensitive to the frequency of giant cell arteritis in cases with PALI and to the relative extra cost of moving from cutting single section to routine levels. CONCLUSIONS: Routinely examining a temporal artery biopsy at multiple levels does not increase the diagnostic yield of the test, although selective further examination may be indicated in some cases. The significance of PALI is uncertain. The cost-benefit of the different strategies in terms of clinical decision making revolve around the perceived risk inherent in not making a diagnosis of giant cell arteritis.

Aged↗
PubMed1999

Meningioangiomatosis: a case report and review of the literature.

A case of cerebral meningioangiomatosis in an adult man without any stigmata of neurofibromatosis is reported. A 22 year-old man with no previous neurological history, presented with adversive seizures; clinical examination and electro-encephalogram were normal. CT showed nodular calcified masses in the left frontal lobe and in the left posterior parietal area. A craniotomy was performed and the frontal lesion was excised. Histological examination showed a predominantly intracerebral tumour involving both grey and white matter, with a complex picture of variable cellularity, dense calcification and prominent perivascular arrangements of reticulin-rich spindle cell fascicles with palisade formation widely involving the brain tissue. Immunohistochemistry for S100 protein varied between different parts of the tumour; there was focal positivity for S100 protein and smooth muscle actin in the lesion with no reaction for GFAP or EMA. Immunostaining for Factor 8-related antigen highlighted the perivascular arrangement of lesional cells and demonstrated an increase in the number of small vessels in other areas. Electron microscopy of the main mass showed elongated spindle cells with formation of pericellular basal lamina. The literature on meningioangiomatosis was reviewed. The evidence for meningeal, perivascular neural plexus or pericyte origin does not appear to be well founded. The present case further illustrates the difficulty in identifying an exact histogenetic cell and probably reflects an origin from a primitive perivascular mesenchymal cell.

Adult↗
PubMed1999

Malignant transformation in pleomorphic xanthoastrocytoma--a report of two cases.

Pleomorphic xanthoastrocytomas (PXA) with malignant transformation are reported in two adult men with a long history of seizures, recent onset of neurological symptoms and superficially located, temporal lobe lesions. Although PXA is generally described as having relatively benign behaviour, this report adds two further cases of malignant transformation to the literature.

Adult↗
PubMed1998

Immunohistochemical analysis of cyclin A in astrocytic tumours.

Cyclins are important regulators of the cell cycle; there is increasing evidence that some cyclins are positively involved in carcinogenesis. Amplification and translocation of the cyclin genes and overexpression of their mRNAs and proteins have been observed in a variety of tumours. We studied cyclin A protein in astrocytic tumours by immunohistochemical analysis. Immunohistochemistry with microwave antigen retrieval was carried out on formalin fixed, paraffin embedded material from 15 glioblastomas (WHO grade IV), 10 anaplastic astrocytomas (WHO grade III), seven diffuse low grade astrocytomas (WHO grade II) and nine pilocytic astrocytomas (WHO grade I) using antibodies against cyclin A and a proliferation marker MIB1. Staining for these antibodies was seen mainly in the tumour cell nuclei; 66% of all cases showing staining for cyclin A and 95% of all cases staining for MIB1. Mean labelling indices (LI) for cyclin a were higher in glioblastoma (mean LI-6.7) and anaplastic astrocytoma (mean LI-5.9) than low grade diffuse astrocytoma (mean LI-1.7) and pilocytic astrocytoma (mean LI-0.12), although there was no clear cut off point between the various tumour types. A good correlation was seen between labelling indices of cyclin A and MIB1 (Pearson correlation coefficient r = 0.59, P < 0.0001). Cyclin A is variably expressed in astrocytic tumours, either reflecting increased tumour proliferation (cyclin A being an integral component of the cell cycle), an alteration of its gene, protein upregulation or regulation of apoptosis. The genetic basis of expression of cyclin A in astrocytic tumours remains to be determined.

Antigens, Nuclear↗
PubMed1998

Craniopharyngioma invading the nasal and paranasal spaces, and presenting as nasal obstruction.

A case of craniopharyngioma invading the nasal and paranasal sinuses and presenting as nasal obstruction is reported. Imaging showed a destructive mass of the skull base with involvement of the nose and paranasal sinuses. In the excised mass mitoses were frequent and the proliferation index was high. Invasion of the nasopharynx and presentation as a nasopharyngeal mass is uncommon for a craniopharyngioma.

Biopsy↗
PubMed1998

A preliminary experimental in vivo study of the effect of photodynamic therapy on human pituitary adenoma implanted in mice.

As surgery alone may prove inadequate to effect a cure for invasive pituitary adenomas, photodynamic therapy (PDT) was investigated as a possible adjuvant treatment for this group of tumours. Different subtypes of human pituitary adenoma cells were implanted subcutaneously into nude mice to study the in vivo effect of PDT on such lesions. The photosensitizer used in this study was polyhaematoporphyrin at a dose of 10 mg/kg b.w., followed by light irradiation at a wavelength of 630 nm with varying light doses between 10 and 75 J/cm2. Histopathological examination of the treated implants consistently showed tumour vascular changes with acute inflammatory reaction, interstitial haemorrhage, and evidence of cell death at higher doses of light. These changes were absent in the control groups. These findings indicate that the cytotoxic effect of PDT demonstrated in vitro in previous studies, is also present in vivo.

Adenoma↗
PubMed1996

Cyclin D1 in astrocytic tumours: an immunohistochemical study.

Forty-eight astrocytic tumours were stained immunohistochemically with antibodies to the cell cycle-regulating protein, cyclin D1, and to the proliferation marker MIB1 (Ki-67) using formalin fixed paraffin embedded tissue and a microwave antigen retrieval system. Cases were classified by the WHO system (1993). The labelling indices (LI) for both antibodies were compared with each other and with the tumour type. The mean labelling indices for both antibodies increased with the degree of malignancy, and a significant difference was seen between the pilocytic astrocytoma and diffuse astrocytoma together vs anaplastic astrocytoma and glioblastoma together. However, within each tumour type there was considerable variation in the labelling indices and a clear cut off value could not be demonstrated. There was a strong positive correlation between labelling indices for cyclin D1 and MIB1 in diffuse astrocytoma, but this correlation broke down increasingly in anaplastic astrocytoma and glioblastoma. There was poor correlation between cyclin D1 and MIB1 in pilocytic astrocytoma, a feature which appeared to separate them from the diffuse astrocytoma. Average labelling indices for cyclin D1 were higher than those of MIB1, which suggests that cyclin D1 positive cells represent a pool of cells from which proliferation and hence MIB1 expression can take place. In conclusion, cyclin D1 is overexpressed in astrocytic tumours, more so with increasing grade of malignancy and in a way which approximately correlates with MIB1 expression.

Antigens, Neoplasm↗
PubMed1996

Priapism associated with sickle cell hemoglobinopathy in children: long-term effects on potency.

PURPOSE: Children with sickle cell priapism have traditionally been treated conservatively with surgery done as a last resort. Only sparse subjective data are available on the long-term assessment of potency in these patients. MATERIALS AND METHODS: We retrospectively reviewed the charts of all pediatric patients with sickle cell priapism who presented to Children's Hospital of Michigan between 1972 and 1992, and subsequently assessed erectile capabilities subjectively by questionnaire and objectively by RigiScan. RESULTS: Of the 15 patients interviewed 5 had undergone shunt procedures. The return of potency tended to vary inversely with patient age at onset and duration of priapism. CONCLUSIONS: Shunts performed within 48 hours, especially in postpubertal children, seemed more likely to preserve potency.

Adolescent↗
PubMed1996

Electron microscopic characteristics of actinomycetic agents having aetiological association with human leprosy and epizootic ulcerative syndrome of fish.

The transmission electron microscopic (TEM) studies of the human leprosy derived chemoautotrophic nocardio-form (CAN) bacteria and EUS derived CAN bacteria showed presence of double contoured cell-walls consisting of an electron transparent and a dense layer. The fibrillar structures on the surface of these CAN bacterial cells also suggested their similarity to the human tissue derived Mycobacterium leprae cells. These EM studies further revealed mycelial and coccoid bodies in all these bacteria as was observed originally.

Actinomycetales↗
PubMed1995

Renin-producing leiomyosarcoma originating in the uterus.

We present a case of uterine leiomyosarcoma in a 60-year-old woman, who had severe hypertension with hypokalaemia and metabolic alkalosis. Investigation revealed an elevated serum renin level; the tumour stained for renin on immunocytochemistry. The serum renin level fell on successful treatment of the primary. We suggest that this is the first reported case of uterine leiomyosarcoma shown to be producing renin.

Female↗
PubMed1995

Acquired rectourethral fistula: methods of repair.

Rectourethral fistulas are a rare but devastating complication of urinary or rectal surgery, trauma or inflammation. Historically repair has posed a challenge because of technical difficulties and the high incidence of recurrent fistulas. We report 7 cases of acquired rectourethral fistulas of varying etiology (3 after prostatectomy, 3 after trauma and 1 after recurrent perineal abscess), which were managed by various means. Our data and those in the literature suggest that the first attempt at repair is the best and subsequent repairs become increasingly difficult; the York Mason approach allows easy accessibility with minimal risk of complications and the best chance for a functionally successful outcome when a vascularized flap is not required, and some cases may have such a low probability of successful resolution of the fistula as well as maintenance of urinary continence that cystectomy and supravesical diversion are appropriate considerations.

Adolescent↗