Browsing by Author "Radhakrishnan, V V"
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Item A dot-immunobinding assay (dot-Iba) for rapid diagnosis of pulmonary tuberculosis.(Indian journal of experimental biology, 2001)IgG antibody to Mycobacterium tuberculosis from the sera of patients with 'definite' pulmonary tuberculosis (PT) was isolated and coupled with Cyanogen bromide-Sepharose 4B. Using an immunoabsorbent affinity chromatography, 14 kDa antigen was recovered from the culture filtrates of M. tuberculosis. With this mycobacterial antigen, a dot immunobinding assay (Dot-Iba) was developed for the detection of specific antibody to M. tuberculosis in the sera of patients with PT and controls. The assay gave positive results in all the 12 sputum-smear positive [acid fast bacilli (AFB)] patients with PT and gave negative results in the 50 sera from control groups. The Dot-Iba as described in this study, is simple, rapid and specific for laboratory diagnosis of PT.Item Advanced magnetic resonance imaging with histopathological correlation in papillary tumor of pineal region: report of a case and review of literature.(Neurology India, 2010)Papillary tumors of the pineal region are recently described as rare mass lesions with limited literature available on their natural history and imaging features. Magnetic resonance imaging (MRI) including perfusion, diffusion, and spectroscopic features were described in an 18-year-old girl with papillary tumor of pineal region. A well-defined, T1 hyperintense and contrast-enhancing mass lesion was noted in pineal region with few cystic spaces within. Solid portion of lesion showed minimal diffusion restriction with average apparent diffusion coefficient of 0.812 Chi 10 -3 mm 2 /s; on MR spectroscopy elevated myo-inositol peak with reduced N-acetylaspartate and elevated choline in the tumor. On perfusion study there was significantly high relative cerebral blood volume (rCBV) (6-9 times) and relative cerebral blood flow (rCBF). Our findings agree with previous descriptions of cystic areas with T1 hyperintense appearance of this tumor but very high level of tumor perfusion, diffusion restriction, and presence of myo-inositol peak are important imaging findings and may correlate with the recent reports of high tumor recurrence in these cases.Item Central nervous system ganglioglioma. A clinicopathologic study.(Indian journal of cancer, 1996)Gangliogliomas are one of the uncommon tumours of central nervous system. Since these tumours have been associated with an indolent clinical course and benign biological behaviour, it is essential to make an accurate histopathological diagnosis of ganglioglioma. In this study the salient clinical and histopathological features in six patients with intracranial ganglioglioma are described.Item Characterization of mycobacterial antigens by Elisa and immunoblot methods.(Indian journal of pathology & microbiology, 1995)Antibodies to two mycobacterial antigens viz - culture filtrate antigen (CFA) and Mycobacterium tuberculosis antigen 5 were raised in rabbits. Enzyme-linked immuno sorbent assay (ELISA) and immunoblot methods were used for the evaluation of the specificity of the rabbit antibodies to M. tuberculosis. Immunoblot method is more sensitive than ELISA for the detection of antibodies to M. tuberculosis in the rabbit sera. It is being emphasised that characterisation of the mycobacterial antigens and evaluation of the specificity of the antimycobacterial antibodies are essential prior to their applications as an adjunct in the laboratory diagnosis of human mycobacterial disease.Item Circulating immune complexes in cerebrospinal fluid of patients with tuberculous meningitis.(Indian journal of experimental biology, 1991)Circulating immune complexes (ICs) were isolated from cerebrospinal fluids (CSFs) of patients with tuberculous meningitis (TBM), non-tuberculous neurological diseases by a polyethylene glycol (PEG) precipitation method. Mycobacterium tuberculosis antigen 5 was detected in CICs of 30% patients with TBM, by sandwich ELISA. CIC level decreases during antituberculosis chemotherapy and therefore its detection can provide a method to monitor the therapeutic schedule in patients with TBM.Item Correlation between the isolation of Mycobacterium tuberculosis and estimation of mycobacterial antigen in cisternal, ventricular and lumbar cerebrospinal fluids of patients with tuberculous meningitis.(Indian journal of pathology & microbiology, 1993)In the study Mycobacterium tuberculosis was isolated in the cerebrospinal fluid (CSF) specimens of patients with tuberculous meningitis (TBM) by the conventional bacteriological technique. The isolation rate of M. tuberculosis was found to be 11.5% in lumbar, 75% in ventricular and 87.5% in cisternal CSFs. Low isolation rate of M. tuberculosis in lumbar CSF is due the low density of tubercle bacilli in lumbar CSF than in cisternal CSF. However M. tuberculosis antigen 5 is present in significant concentration in CSFs. The antigen concentration in CSF was estimated by an inhibition enzyme-linked immunosorbent assay (ELISA). Since CSF specimens can not be collected from ventricular or cisternal routes for the routine bacteriological investigations in patients with TBM, estimation of M. tuberculosis antigen 5 concentration in lumbar CSF by an inhibition ELISA may be considered as an adjunct in the laboratory diagnosis of TBM. This is particularly relevant in those patients in whom bacteriological methods fail to demonstrate M. tuberculosis in CSF specimens.Item Demonstration of Lafora bodies in a patient with myoclonus epilepsy.(The Journal of the Association of Physicians of India, 1996)Item Diagnosis of tuberculous meningitis by enzyme-linked immuno-sorbent assay (ELISA), using an affinity chromatography purified mycobacterial antigen.(The Journal of the Association of Physicians of India, 1994)Using an immunoabsorbent affinity chromatography, a mycobacterial antigen was isolated from culture filtrate of H37Ra Mycobacterium tuberculosis (MTB). The immunoabsorbents were prepared by coupling cynogen bromide-activated Sepharose-4B with human IgG antibody to MTB. Cerebrospinal fluids (CSF) from 10 culture positive, 30 culture negative patients with tuberculous meningitis (TBM) were assayed, for IgG antibody to this mycobacterial antigen by ELISA. CSFs from 50 patients with non-tuberculous neurological diseases were selected as control group. At a selected 'cut off' titre of 1:80, 21 out of 30 CSFs from culture negative patients gave positive results. No false negative result was observed in CSF from 10 culture positive patients with TBM. No false positive results were recorded in CSFs of 50 patients with non-tuberculous neurological diseases. Technical aspects involved in the isolation of this myobacterial antigen and its potential applications in the laboratory diagnosis of TBM have been emphasised in this study.Item Diagnostic utility of immunohistochemical techniques in intramedullary Schwann-cell tumours.(Indian journal of pathology & microbiology, 1993)Histopathologic features in two intramedullary schwann-cell tumours, closely resembled with those of fibrillary astrocytoma and could not be differentiated from each other by the conventional histochemical stains. However application of tumour markers-Glial fibrillary acidic protein (GFAP) and S-100 protein were found to be useful in differentiating these two tumours and thus helped in making an accurate histopathological diagnosis in these two patients.Item Diffuse form of primary leptomeningeal gliomatosis--a case report.(Indian journal of pathology & microbiology, 1994)Item Disseminated intra-cerebral microabscesses: a clinico-pathologic study.(Indian journal of pathology & microbiology, 1994)In this retrospective study, clinical and neuropathological features were analysed in eight patients with disseminated intracerebral microabscesses. All the patients presented with clinical features, suggestive of an encephalopathic process of an acute onset. Neuroradiological and laboratory investigations were not helpful in establishing the diagnosis in any patient during their hospital stay. All the eight patients died in the hospital and at autopsy disseminated intracerebral microabscesses were the most striking feature. In two patients hyphae of Candida albicans were demonstrated within the microabscesses. Gram negative bacilli in two patients and gram positive and gram positive cocci in one patient were demonstrated in the microabscesses. Disseminated intra-cerebral microabscesses are usually an unrecognised manifestation of central nervous system infections and should be considered in the differential diagnosis of patients with encephalopathy of unknown aetiology.Item Dot-immunobinding assay.(Methods in molecular biology (Clifton, N.J.), 2009)Dot-immunobinding assay (Dot-Iba) is a simple and highly reproducible immunodiagnostic method. Antibody or antigen is dotted directly onto nitrocellulose membrane (NCM) discs. The diagnostic material to be checked can be incubated on this disc. Presence of antigen-antibody complex in NCM discs can be directly demonstrated with enzyme-conjugated antiglobulins and substrate. Development of a purple-pink colored, insoluble substrate product in the NCM will be considered a positive result in the assay. This assay allows the processing of multiple specimens at a time and the entire operational procedures require only 4-6 h. Dot-Iba is rapid, and the technical steps involved in the assay are much simpler than in the other immunoassays such as enzyme-linked immunosorbant assay in detecting circulating antigen and antibody in clinical samples. The Dot-Iba showed an overall sensitivity of 60% for tuberculous meningitis diagnosis and no false positive results were encountered. Hence, this assay is highly specific for the diagnosis of paucibacillary diseases such as extrapulmonary tuberculosis. Dot-Iba is best suited to laboratories in developing world where there are constraints in laboratory resources.Item Dysembryoplastic neuroepithelial tumour of the central nervous system--a case report.(Indian journal of pathology & microbiology, 1997)Dysembryoplastic neuroepithelial tumour (DNT) of the central nervous system is a recently recognized entity. We describe the clinical and characteristic histomorphological features in a patient with DNT. As this lesion carries a favourable prognosis, it becomes essential to make an accurate histopathological diagnosis.Item Dysplastic gangliocytoma of the cerebellum (Lhermitte-Duclos disease)--a case report with review of the literature.(Indian journal of cancer, 1992)Dysplastic gangliocytoma of the cerebellum is an uncommon malformative lesion and clinically manifest as a slow growing space occupying lesion. In this report, the characteristic clinical and histopathological features of a case of dysplastic gangliocytoma of the cerebellum are described.Item Evaluation of purified protein derivative in the laboratory diagnosis of tuberculous meningitis.(The Journal of the Association of Physicians of India, 1992)An enzyme-linked immunosorbent assay (ELISA) was standardised for the quantitation of IgG antibody in cerebrospinal fluid (CSF) specimens of patients with tuberculous meningitis (TBM). Purified protein derivative (PPD1) from H37Ra M tuberculosis was used as the antigen in the assay. The sensitivity of the ELISA with this antigen was evaluated in the CSF of 10 culture positive and 40 culture negative patients with TBM. The specificity of the assay was evaluated in the CSF of 50 patients with non-tuberculous neurological diseases (control group). The results obtained with this antigen were compared with commercially available tuberculin purified protein derivative (PPD2) and BCG antigens. PPD2 gave false negative results (50%) in culture positive patients with TBM, and BCG antigen gave false positive results in 32% of non-tuberculous subjects. PPD1 gave a sensitivity of 60% in culture negative patients with TBM and no false positive reactions in the non-tuberculous group. PPD1 antigen, in contrast to other mycobacterial antigens, can be very easily prepared in any routine laboratory, and this antigen is recommended for use as an aid in the laboratory diagnosis of TBM, particularly in culture negative patients with TBM.Item Expanding cyst following temporal lobectomy: an unusual complication of epilepsy surgery.(Clinical neurology and neurosurgery, 1999)Following anterior temporal lobectomy performed to control intractable complex partial seizures (CPS), it is rare to find a symptomatic cyst at the lobectomy site causing increased intracranial pressure and neurological deterioration. We report a 24-year-old lady who underwent anterior temporal lobectomy with extended amygdalohippocampectomy for CPS of temporal lobe origin. Ten months following the procedure, she developed a large expanding cyst at the temporal lobectomy site manifesting with recurrence of CPS, progressive focal neurological deficit and increased intracranial pressure. The patient underwent a repeat craniotomy, decompression of the cyst along with wide excision of the wall and fenestration of the arachnoid membrane into the basal cisterns. Following the procedure, the features of increased intracranial pressure and focal neurological deficit promptly improved and her seizures became better controlled. Craniotomy and fenestration of a symptomatic iatrogenic cyst following temporal lobectomy results in clinical improvement, obviating the need for a permanent cystoperitoneal shunt.Item Glial and cartilagenous differentiation in medulloblastoma--a case report.(Indian journal of pathology & microbiology, 1994)Item Gliomatosis cerebri--a case report.(Indian journal of cancer, 1996)Gliomatosis cerebri is a vary rare neoplastic lesion of the central nervous system. An intra-vitam diagnosis of gliomatosis cerebri can be suggested with a steleolactic biopsy of the lesion in conjunction with Magnetic Resonance Imaging (MRI) findings in the brain.Item Granular cell tumour (choristoma) of the neurohypophysis--a report of two cases.(Indian journal of pathology & microbiology, 1997)Granular cell tumours of the neurohypophysis are uncommon and only 30 cases are documented in the literature till 1994. In this communication, the salient clinical and histomorphological features in two patients with granular-cell tumour of the neurohypophysis are described.Item Immunohistochemical demonstration of mycobacterial antigens in intracranial tuberculoma.(Indian journal of experimental biology, 1991)Mycobacterial antigens have been demonstrated immunohistochemically in the paraffin sections of 10 intracranial tuberculous granulomas and the results were compared with the detection of acid fast bacilli by conventional Ziehl-Neelsen method. In none of the 10 specimens, acid fast bacilli were demonstrated while mycobacterial antigens were characterised as diffusely staining granular brownish-pink material within the cytoplasm of giant cells and macrophages. In 14 specimens of granulomatous lesions due to non-tuberculous aetiology, immunohistochemical stains were negative for mycobacterial antigen. Thus demonstration of mycobacterial antigen will be not only useful in establishing mycobacterial aetiology of a caseating intracranial granuloma but also can be used as an alternative method to the conventional Ziehl-Neelsen method.