Browsing by Author "RADHAKRISHNAN, VV"

Now showing 1 - 20 of 22
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    A DOT-IMMUNOBINDING ASSAY FOR THE LABORATORY DIAGNOSIS OF TUBERCULOUS MENINGITIS AND ITS COMPARISON WITH ENZYME-LINKED-IMMUNOSORBENT-ASSAY
    (JOURNAL OF APPLIED BACTERIOLOGY, 1991)
    In an attempt to establish an alternative to standard bacteriological methods in the laboratory diagnosis of tuberculous meningitis (TBM), a simple dot-immunobinding assay (Dot-Iba) was standardized to detect Mycobacterium tuberculosis antigen 5 and antimycobacterial antibody in cerebrospinal fluid (CSF) specimens of patients with TBM. Sensitivity and specificity of Dot-Iba was compared with conventional enzyme-linked immunosorbent assay (ELISA) and standard bacteriological techniques. The Dot-Iba showed excellent correlation with indirect ELISA for the detection of antimycobacterial antibody in CSF and showed 60% sensitivity and 100% specificity in culture-negative patients with TBM. However Dot-Iba was less sensitive for the detection of antigen 5 in CSFs and showed false negative results (60%) in culture-positive patients with TBM.
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    APPLICATION OF SILVER COLLOIDAL STAINING METHOD IN THE DIAGNOSIS OF INTRACRANIAL GLIOMA
    (INDIAN JOURNAL OF MEDICAL RESEARCH SECTION B-BIOMEDICAL RESEARCH OTHER THAN INFECTIOUS DISEASES, 1993)
    A silver colloidal staining technique for the demonstration of argyrophilic nucleolar organizer regions (Ag-NORs) was used on the paraffin sections of reactive gliosis and grade I astrocytoma tissue. Quantitative as well as qualitative differences of Ag-NORs were found between the cells of reactive gliosis and grade I astrocytoma. In cases of reactive gliosis, the Ag-NOR counts averaged 1.19 +/- 0.16 per nucleus, while in grade I astrocytoma, Ag-NOR counts averaged 2.36 +/- 0.32 per nucleus (P<0.05). Compound Ag-NORs were also seen in the nuclei of cells in grade I astrocytoma while they were not present in the nuclei of cells in cases of reactive gliosis. The results of the study indicate that Ag-NOR technique is an useful method and can be applied in situations where a distinction between grade I astrocytoma and reactive gliosis becomes difficult at the light microscopic level.
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    CHOROID-PLEXUS PAPILLOMAS
    (BRITISH JOURNAL OF NEUROSURGERY, 1994)
    Choroid plexus papillomas (CPPs) are rare neoplasms accounting for less than 1% of all intracranial tumours. We present our experience with 13 consecutive cases managed by us between 1981 and 1991. There were eight children and five adults. Five patients had tumours in the 4th ventricle, four in lateral ventricle, one in the 3rd ventricle, two in the cerebellomedullary cistern and one in the cerebellopontine angle. The cerebellomedullary cistern is a rare site for CPPs. Although the 4th ventricle remains the common site for adult CPPs, in our series there was a higher incidence of posterior fossa papillomas even in children. Only six patients out of 13 underwent precraniotomy shunts. All patients had their tumours operated upon and verified histologically. Total excision of he tumour could be achieved in nine patients; only a sub total excision was possible in the remaining four. There were two surgical mortalities in the earlier part of this series. Two patients with subtotal excisions underwent radiation therapy; one of these had regrowth of the tumour and another was lost to follow up. The other nine patients are doing well with a follow-up ranging from 9 to 90 months. Surgical resection with the objective of achieving total excision should be attempted in these tumours.
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    CORRELATION BETWEEN CULTURE OF MYCOBACTERIUM-TUBERCULOSIS AND DETECTION OF MYCOBACTERIAL ANTIGENS IN CEREBROSPINAL-FLUID OF PATIENTS WITH TUBERCULOUS MENINGITIS
    (JOURNAL OF MEDICAL MICROBIOLOGY, 1990)
    A retrospective study was done to correlate culture of Mycobacterium tuberculosis and detection of mycobacterial antigen in cerebrospinal fluid (CSF) by an inhibition enzyme-linked immunosorbent assay (ELISA). M. tuberculosis was cultured from CSF of 14 out of 70 patients with a clinical diagnosis of tuberculous meningitis (TBM). Mycobacterial antigens were demonstrated in CSF specimens by inhibition ELISA in all 14 culture-positive patients with antigen concentrations of 14.5-295 ng/ml (mean 158.8 ng/ml). Thus there was positive correlation between the detection of mycobacterial antigen and isolation of M. tuberculosis. Based on this observation, 56 CSF specimens from culture-negative patients with clinically diagnosed TBM were examined for mycobacterial antigen and the data were compared with those from culture positive patients. ELISA gave positive results in 38 specimens, with antigen levels of 12.5-280 ng/ml (mean 152.6 ng/ml). In 70 CSF specimens from patients with non-tuberculous neurological disease (control group), ELISA results were negative. Thus, detection of mycobacterial antigen in CSF specimens by inhibition ELISA had a specificity of 100% and a sensitivity of 67.8% for the diagnosis of TBM and is of potential value in the laboratory diagnosis of TBM.
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    DETECTION OF MYCOBACTERIUM-TUBERCULOSIS ANTIGEN-5 IN CEREBROSPINAL-FLUID BY INHIBITION ELISA AND ITS DIAGNOSTIC POTENTIAL IN TUBERCULOUS MENINGITIS
    (JOURNAL OF INFECTIOUS DISEASES, 1991)
    Inhibition ELISA was used to quantitate Mycobacterium tuberculosis antigen 5 in cerebrospinal fluid (CSF) specimens of 40 patients with a clinical diagnosis of tuberculous meningitis. In all 10 culture-proven patients, the assay was positive; in 30 culture-negative patients, the assay yielded positive results for 21. CSF antigen 5 concentrations ranged from 9 to 82 ng/ml (mean +/- SD, 45.5 +/- 6.2). In 40 patients with nontuberculous neurologic diseases, mean concentration was 1.45 ng/ml. Thus, inhibition ELISA for the detection of M. tuberculosis antigen 5 in CSF has definite diagnostic potential during the active phase of the disease and should be a routine diagnostic test, particularly when bacteriologic cultures in CSF are negative for M. tuberculosis.
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    DIAGNOSTIC-SIGNIFICANCE OF CIRCULATING IMMUNE-COMPLEXES IN PATIENTS WITH PULMONARY TUBERCULOSIS
    (JOURNAL OF MEDICAL MICROBIOLOGY, 1992)
    A polyethylene glycol (PEG) precipitation method was used to examine sera of patients with active pulmonary tuberculosis (PT), leprosy and non-tuberculous pulmonary diseases and of healthy control subjects for immune complexes (ICs). Mycobacterium tuberculosis antigen 5 was detected in the ICs in 80% of patients with PT by the indirect (sandwich) enzyme-linked immunosorbent assay (ELISA). Detection of mycobacterial antigen in ICs has diagnostic potential as an adjunct in the laboratory diagnosis of PT, particularly when repeated bacteriological investigations for M. tuberculosis in clinical specimens are negative. Levels of ICs tend to decrease with the duration of anti-tuberculosis chemotherapy and their detection can also be used to assess the clinical response to therapy in patients with PT.
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    ELISA OF IGG ANTIBODY TO MYCOBACTERIUM-TUBERCULOSIS ANTIGEN-5, PPD IN CSF IN TUBERCULOUS MENINGITIS PATIENTS
    (INDIAN JOURNAL OF MEDICAL RESEARCH SECTION A-INFECTIOUS DISEASES, 1990)
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    HISTOPATHOLOGICAL EVALUATION OF POLYMETHYL METHACRYLATE AS AN EMBOLIC AGENT
    (ACTA NEUROCHIRURGICA, 1992)
    Polymethyl methacrylate (PMMA) microspheres were used as an embolic agent to reduce the vascularity in eight patients with intracranial vascular tumours. Post embolization angiograms showed 30-60% reduction in the vascularity of-the tumours. No patient developed any neurological complications in the immediate post-embolization period. These eight patients subsequently underwent surgery for the removal of their tumours. During surgery there was minimal blood loss and a good plane of cleavage was obtained between the tumour and the adjacent brain. The surgical specimens were examined histopathologically for the effects of PMMA. PMMA microspheres, in contrast to other cyano-acrylates-Isobutyl-2-cyanoacrylate (IBCA) - did not elicit either inflammatory reaction or mural angionecrosis within the wall of the embolised vessels. The histopathological studies suggest that PMMA microspheres are an inert material and can be used as an adjunct in the management of intracranial vascular tumours.
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    HYDROLYZED MICROSPHERES FROM CROSS-LINKED POLYMETHYL METHACRYLATE (HYDROGEL) - A NEW EMBOLIC MATERIAL FOR INTERVENTIONAL NEURORADIOLOGY
    (JOURNAL OF NEURORADIOLOGY, 1991)
    Highly hydrophilic, perfectly smooth and spherical microspheres have been synthetized. These non-biodegradable microspheres absorb water in varying degrees and can be injected easily through microcatheters due to their slippery and compressible characteristics. The material was successfully used of embolization of 4 vascular intracranial tumours and 2 spinal vascular lesions in the cervical region, by superselective delivery. Histopathology confirmed absolute inertness of the microspheres.
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    IGG ANTIBODY TO MYCOBACTERIUM-TUBERCULOSIS ANTIGEN-5 IN CEREBROSPINAL-FLUID AND ITS DIAGNOSTIC APPLICATION IN TUBERCULOUS MENINGITIS
    (INDIAN JOURNAL OF EXPERIMENTAL BIOLOGY, 1990) MATHAI, A; RADHAKRISHNAN, VV; SEHGAL, S
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    IMMUNOELECTROPHORESIS OF MYCOBACTERIAL ANTIGENS
    (INDIAN JOURNAL OF EXPERIMENTAL BIOLOGY, 1990)
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    INTRADURAL SPINAL CAVERNOMAS
    (BRITISH JOURNAL OF NEUROSURGERY, 1992)
    Intradural cavernomas are rare vascular lesions of the spinal cord. Four cases of histologically verified cavernomas of the cord are reported, of which two were extramedullary and two were intramedullary in location. Progressive neurological deficit was the presenting feature in three cases while one patient had a rapid evolution of neurological deficits and was found at surgery to have had bled from the extramedullary lesion. All the patients were subjected to surgery and total excision of the cavernomas was carried out in each case. While two patients improved after surgery the other two remained static. The available literature on spinal cord cavernomas is reviewed.
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    MYCOTIC-ANEURYSMS OF THE INTRACRANIAL VESSELS
    (INDIAN JOURNAL OF MEDICAL RESEARCH, 1994)
    The salient clinical and pathological features are reported of Aspergillus cerebral aneurysms in four young women who had undergone intra-abdominal surgery under spinal anaesthesia and developed clinical features of meningitis 7-16 days postoperatively. The circle of Willis showed ruptured aneurysm in the basilar artery and its branches. The role of iatrogenic factors in the pathogenesis of Asgergillus cerebral aneurysms is highlighted.
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    NUCLEOLAR ORGANIZER REGIONS IN MENINGIOMAS
    (BRITISH JOURNAL OF NEUROSURGERY, 1993)
    Paraffin sections of 305 meningeal tumours were analysed for the presence of nucleolar organizer region (Ag-NOR) in the neoplastic cells, using a one step silver-colloidal staining method. The mean (+/- SEM) Ag-NOR counts were 2.73 +/- 0.21 for atypical and 2.91 +/- 0.18 for papillary variants of meningioma. In meningotheliomatous and transitional variants of meningioma, the mean Ag-NOR counts were 1.41 +/- 0.34 and 1.38 +/- 0.31, respectively. The recurrence rates were significantly higher in atypical meningiomas than in other histopathological variants (p < 0.05). Differences in the mean Ag-NOR numbers between meningothelial and transitional variants in their primary and recurrent tumours were not significantly different (p > 0.05). The results of this study indicates that estimation of Ag-NOPs can be applied in predicting the aggressive clinical behaviour of primary meningeal tumours.
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    POTENTIAL APPLICATION OF DOT-IMMUNOBINDING ASSAY AS A RAPID DIAGNOSTIC-TEST IN TUBERCULOUS MENINGITIS
    (INDIAN JOURNAL OF EXPERIMENTAL BIOLOGY, 1991)
    A simple dot-immunobinding assay (Dot-Iba) in nitrocellulose paper was developed for the detection of specific IgG antibody to Mycobacterium tuberculosis antigen 5 and mycobacterial antigen in cerebrospinal fluid of patients with tuberculous meningitis (TBM). The assay gave 77.1% sensitivity for the detection of IgG antibody to M. tuberculosis antigen 5 and 48.6% sensitivity for the detection of mycobacterial antigen in patients with TBM.