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Biomedical subjects

V V Radhakrishnan

Publications and source records attributed to V V Radhakrishnan.

At least 109 records · Page 6Linked to original sources
PubMed1990

Correlation between culture of Mycobacterium tuberculosis and IgG antibody to Mycobacterium tuberculosis antigen-5 in the cerebrospinal fluid of patients with tuberculous meningitis.

A retrospective study was made of the correlation between culture of Mycobacterium tuberculosis and detection of IgG antibody to M. tuberculosis antigen-5 in cerebrospinal fluid (CSF) by means of an enzyme linked immunosorbent assay (ELISA). Mycobacterium tuberculosis was cultured from the CSF in 14 of 70 patients with a clinical diagnosis of tuberculous meningitis (TBM). IgG antibody to M. tuberculosis antigen-5 was demonstrated in significant titres (80-640) in all 14 culture-positive patients. Thus, positive correlation was observed between culture of M. tuberculosis and detection of IgG antibody in the CSF. As a result of this observation, the CSF from 56 culture-negative patients with a clinical diagnosis TBM was specifically investigated for the detection of IgG antibody to M. tuberculosis antigen-5 and the findings were correlated with those of culture-positive patients. The assay was positive in 34 of 56 patients, the antibody titre ranging between 80 and 640. In the CSF of 70 patients with non-tuberculous neurological diseases, the assay was negative at a dilution of 1 in 80. Thus, detection of IgG antibody to M. tuberculosis antigen-5 by indirect ELISA carried 100% specificity and 60.7% sensitivity for a tuberculous aetiology in culture-negative patients with TBM. The results of this study suggest that indirect ELISA for IgG antibody to M. tuberculosis antigen-5 in CSF holds definite promise in diagnosis of TBM, particularly when repeated cultures of CSF are negative for M. tuberculosis.

Antibodies, Bacterial↗
PubMed1990

Correlation between culture of Mycobacterium tuberculosis and detection of mycobacterial antigens in cerebrospinal fluid of patients with tuberculous meningitis.

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.

Antigens, Bacterial↗
PubMed1990

Detection of mycobacterial antigen in cerebrospinal fluid in patients with chronic meningitis by inhibition enzyme linked immunosorbent assay.

In a retrospective study, cerebrospinal fluid (CSF) specimens from 50 patients of chronic meningitis were investigated for tuberculous etiology by inhibition enzyme-linked immunosorbent assay (ELISA). CSF specimens from 10 patients of tuberculous meningitis in whom Mycobacterium tuberculosis was isolated, formed the positive control group of this study. The assay yielded positive results in CSF specimens for mycobacterial antigens in 8 of the 50 patients of chronic meningitis. No false positive results were recorded in 50 patients of non-meningitic (negative control group) neurological diseases. Inhibition ELISA procedure described here is reproducible and had 100 per cent specificity for tuberculous etiology. This assay could be applied as a diagnostic tool for tuberculous etiology, particularly in patients of chronic meningitis in whom repeated CSF cultures for any microbial agents are negative.

Antigens, Bacterial↗
PubMed1990

Immunoelectrophoresis of mycobacterial antigens.

Polyvalent antiserum to culture filtrate of H37 Ra M. tuberculosis was raised in rabbits. Monospecific antiserum was raised against M. tuberculosis antigen-5, prepared from the culture filtrates by immunoabsorbent affinity chromatography. On immunoelectrophoresis, antigen-5 demonstrated single precipitin arc against polyvalent and monospecific antisera. The culture filtrate antigen demonstrated multiple precipitin arcs against polyvalent antiserum and single precipitin are against monospecific antiserum. Antigen-5 could be isolated and characterized from the culture filtrate of H37 Ra M. tuberculosis. Immunoelectrophoresis could be one of the method to characterize the mycobacterial antigens prepared in the laboratory.

Animals↗
PubMed1990

IgG antibody to Mycobacterium tuberculosis antigen-5 in cerebrospinal fluid and its diagnostic application in tuberculous meningitis.

IgG antibody to M. tuberculosis antigen-5 was detected by non-competitive ELISA in cerebrospinal fluid specimens (CSF), from 40 patients with clinical diagnosis of tuberculous meningitis and in 42 patients of non-tuberculous neurological diseases. The geometric mean antibody titer in CSF specimen for tuberculous and non-tuberculous groups were 156 and 8 respectively. The antibody titer in CSF specimens showed no correlation to IgG levels, tuberculin reactor status and duration of chemotherapy in patients with tuberculous meningitis. At a dilution end-point 1:40, the assay had a sensitivity of 84% and specificity of 92%. However at dilution end-point 1:80, the specificity of the assay could be increased to 100% but sensitivity of the assay decreased to 75%. IgG antibody detection against M. tuberculosis antigen-5 by non-competitive ELISA, described in this communication has potential application in the laboratory diagnosis of tuberculous meningitis, particularly in developing countries where the incidence and prevalence of tuberculous meningitis is still high. In culture-negative cases of tuberculous meningitis, non-competitive ELISA could be applied as an alternative diagnostic tool.

Antibodies, Bacterial↗
PubMed1990

ELISA of IgG antibody to Mycobacterium tuberculosis antigen-5, PPD in CSF in tuberculous meningitis patients.

IgG antibody to M. tuberculosis antigen-5 and tuberculin purified protein derivative (PPD) was measured by enzyme linked immunosorbent assay (ELISA) in cerebrospinal fluid (CSF) specimens of 55 patients with tuberculous meningitis (TBM) and 55 patients with non-tuberculous neurological diseases (control group). The geometric mean antibody titre in CSF specimens of TBM patients was 82.4 with antigen-5 and 96.5 with PPD. In the control group, the geometric mean antibody titres for these antigens in CSF specimens were 4.6 and 10.8 respectively. The antibody titres did not show any correlation with tuberculin reactor status, duration of chemotherapy and IgG levels in CSF specimens in patients with TBM. At dilution end point 1:80, specificity of the assay was 100 per cent with antigen-5 and sensitivity of the assay was 70.9 per cent. False positivity observed in the control group with PPD antigen could be eliminated in 1:80 dilution in the assay with antigen-5. Antigen-5 is more specific than PPD antigen for the diagnosis of tuberculous meningitis.

Antibodies, Bacterial↗
PubMed1988

Effects of cyclosporin A and predegeneration on survival and regeneration of peripheral nerve allografts in rabbits.

Axonal regeneration across 64 median nerve grafts in 34 rabbits was studied histologically to determine the optimal conditions for nerve allografting. Axonal regeneration across allografts in cyclosporin A-treated animals was satisfactory, but it occurred more slowly and with more inflammation and fibrosis than in autografts. Without immunosuppression, fresh allografts were rejected. However, in immunocompetent hosts, allografts rendered less immunogenic by predegeneration were not rejected, and axonal regeneration occurred. The combination of cyclosporin A and nerve graft predegeneration produced the most substantial axonal regeneration, comparable to autografts. The observations suggest that nerve allograft survival may be optimally effected by cyclosporin A treatment coupled with reduction in the immunogenicity of the grafts, such as by predegeneration.

Animals↗
PubMed1984

Exploration of the pineal region: observations and results.

Experience with direct exploration of the pineal region in 22 consecutive patients is reported. Of these cases, mass lesions with obstructive hydrocephalus were found in 19; the remaining 3 had arteriovenous malformations of the pineal region. Of the 19 mass lesions, 5 (26%) were benign and curable. Although a preliminary shunt was routinely provided in all patients with obstructive hydrocephalus before exploration of the pineal region, the condition of five (26%) worsened after the shunt operation, requiring emergency decompression of the pineal tumor. A transtentorial approach through a right occipital craniotomy was uniformly employed in all cases. Overall mortality was less than 5%. These observations and results support the policy of direct exploration of all lesions in the pineal region.

Adolescent↗
PubMed1983

Symptomatic rathke's cleft cysts.

Two unusual cases of symptomatic Rathke's cleft cysts are reported. In one, the cyst was entirely suprasellar with a normal sella turcica. The gross visual failure, hypothalamic disturbances, and hypopituitarism of the patient resolved after a transfrontal aspiration and partial excision of the wall of the cyst. The second patient was a pituitary dwarf with hypothalamic dysfunction, but with normal vision. The patient had a large intrasellar cyst that exhibited marked suprasellar extension with calcification of the capsular rim. After transsphenoidal aspiration and partial excision of the wall of the cyst, the patient achieved a satisfactory recovery. The differential features between Rathke's cleft cyst and craniopharyngioma are highlighted.

Adult↗
PubMed1983

Cervical intramedullary schwannoma. Case report.

A case of cervical intramedullary schwannoma without evidence of von Recklinghausen's disease is reported. The hypotheses regarding its histogenesis and the difficulty in diagnosis on the frozen section obtained at biopsy are discussed, along with a review of literature covering 15 previously reported cases.

Biopsy↗
PubMed1982

Skeletal muscle involvement in tropical endomyocardial fibrosis.

Evidence for neuromuscular dysfunction was sought in 20 consecutive, angiographically proven cases of tropical endomyocardial fibrosis (Group I). Statistical comparison was made with equal number of age, sex and weight-matched normal healthy volunteers (Group II), as well as similarly matched cases of consecutive heart failure (Group III). A myopathic pattern in the EMG was found in 85% of Group I and 65% of Group III patients. However, the severity and global extent of the EMG changes was much more marked in Group I than in Group III. The summed motor unit potential duration was reduced by 20.1% in Group I and by 9.5% in Group III. Corresponding figures for summed motor unit potential amplitude were 27.9% and 15.4%. the summed frequency of polyphasic potentials was significant in Group I and in Group III. Involvement of 3 or 4 muscles in the same patient was found in 80% of Group I, n 10% of Group III. The upper limb muscles were affected in 80% of Group I and 50% of Group III. The motor nerve conduction velocity and distal latency time were normal in all the patients. It is suggested therefore that the myopathic EMG changes in Group I patients may be related to the disease process itself, rather than a reflection of long standing CHF alone. Light-microscopic study of the quadriceps muscles in 8 patients of Group I did not reveal any abnormality.

Adolescent↗
PubMed1982

The role of hyaluronidase in experimental cryptococcal infections.

Cryptococcal infection established in adult male albino rats under experimental conditions produced minimal tissue response to the infection, probably owing to the presence of cryptococcal capsular polysaccharide. Following hyaluronidase administration in the active phases of experimental cryptococcal infection, we have observed characteristic histiocytic granulomatous transformation in cerebral as well as extracerebral lesions. It is postulated that hyaluronidase depolymerizes the capsular mucopolysaccharide of Cryptococcus neoformans and causes its lysis. As a consequence, cryptococcal yeasts that are devoid of their protective capsule and exposed to the host phagocytic system evoke a granulomatous response. Possible application of hyaluronidase as an adjuvant in the therapy of cryptococcal infections needs to be assessed.

Animals↗
PubMed1980

Communicating cystic craniopharyngioma.

The case of a 12-year-old boy, who presented with a suprasellar cystic craniopharyngioma that freely communicated with the third ventricle, as demonstrated by ventriculography, is reported. This observation was confirmed at autopsy. The literature is reviewed briefly and the compatibility with life is discussed.

Brain Diseases↗
PubMed1979

Hypervascular cavernous angioma at angiography.

Arteriovenous malformations usually do not present any diagnostic difficulty on the angiograms. However, small cryptic and cavernous angiomas cannot be demonstrated directly by arteriography because of either sluggish circulation or thrombosis. The present communication documents a relatively rare case of histologically proven cavernous angioma with a hypervascular pattern on the arteriogram.

Brain Neoplasms↗
PubMed1978

Cerebral mucormycosis--a case report.

A case of cerebral fungal granuloma with histological evidence of vasculitis is reported and the literature briefly reviewed. The value of surgery and chemotherapy for this entity which cured the patient without any sequelae of the disease process or chemotherapeutic agent is emphasized.

Adult↗