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Biomedical subjects

S Prabhakar

Publications and source records attributed to S Prabhakar.

At least 127 records · Page 7Linked to original sources
PubMed1997

Comparison of cellular responses in single- and multiple-lesion neurocysticercosis.

Leucocytes from 14 cases of neurocysticercosis who had multiple lesions showed a significantly lower level of chemotaxis than those from healthy controls [with mean (S.D.) movements of 49.86 (15.0) and 89.1 (12.9) microns, respectively; P < 0.05). In contrast, the leucocytes from 14 cases with single lesions had similar chemotactic responses to the controls. Although the level of lymphoproliferation stimulated with phytohaemagglutinin, a measure of T-lymphocyte function, was also considerably less using cells from the multiple-lesion cases than when cells from the single-lesion cases were used, the difference was not statistically significant [0.644 (0.248) of control values v. 0.463 (0.317); P < 0.1]. Flow cytometry indicated that the total numbers of CD4 cells and CD4/CD8 ratios in all blood samples were normal. It therefore appears that, among neurocysticercosis patients, only those with multiple lesions have defective neutrophils and may also have dysfunctional lymphocytes.

Adolescent↗
PubMed1997

Cerebellar degeneration following neuroleptic malignant syndrome.

A 55-year-old woman with a history of bipolar affective disorder developed hyperpyrexia, rigidity and depressed consciousness (neuroleptic malignant syndrome) after commencing neuroleptic therapy. On regaining consciousness, she was mute and had signs suggesting pancerebellar involvement. Hyperpyrexia, which is a cardinal feature of neuroleptic malignant syndrome, may have caused cerebellar damage. Neuroleptic malignant syndrome needs both early recognition and prompt treatment to obviate devastating complications.

Cerebellar Diseases↗
PubMed1996

Low salt intake down-regulates the guanylin signaling pathway in rat distal colon.

BACKGROUND & AIMS: Guanylin, an endogenous gastrointestinal peptide, causes the translocation of NaCl from interstitial fluid to the intestinal lumen. The aim of this study was to examine whether changes in dietary salt intake lead to compensatory changes in expression of the guanylin signaling pathway. METHODS: Rats received low-, normal-, or high-sodium diets for 1 week. Colonic guanylin expression was evaluated by Western and Northern blotting, rates of guanylin secretion by measuring biologically active guanylin released into the medium from colon explants, and expression of the guanylin receptor (C-type guanylate cyclase) by Northern blotting and bioassay. RESULTS: By every criterion, the low-salt diet reduced expression of guanylin to 30%-40% of the level found in control animals. Guanylin receptor expression was also decreased, although less dramatically and with a lower statistical significance. For both guanylin and guanylin receptor, the high-salt diet had no significant effect on expression. CONCLUSIONS: The data support the hypothesis that the guanylin pathway is down-regulated as an adaptive response to salt restriction.

Animals↗
PubMed1996

Evaluation of epilepsy management in a developing country: a prospective study of 407 patients.

407 patients (248 men, 159 women) of epilepsy attending the neurology clinic were evaluated to find out the profile of epilepsy, cost-effectiveness of various investigations, therapeutic regimens and efficacy of referring physicians in a developing country. At the time of onset of seizures 67.2% of patients were in the second and third decade. Generalised tonic clonic seizures were the commonest seizure type seen. Specific aetiology was established in 20.8% cases only. Neurocysticercosis was the commonest cause observed. The main source of referral (50.1%) was general practitioners. Referral diagnosis was incomplete in 52.8% of the cases. Investigations did not alter the diagnosis in 62.5% cases. The EEG was useful in the management of 15.1% cases of epilepsy. The skull x-ray and chest x-ray were abnormal in 1.7% and 2% cases respectively. CT scan revealed abnormality in 39.4% cases. Most of the patients were treated with monotherapy. Phenytoin, phenobarbitone and carbamazepine were the common drug used. Out of 246 cases who were started on anticonvulsant therapy prior to referral, the choice of drug was wrong in 78 (31.7%) cases and dose was inappropriate in 121 (49.2%) cases. It was concluded that most important factor for cost effective management of epilepsy is proper clinical evaluation and education of general physicians in this direction.

Adolescent↗
PubMed1996

Outcomes in the Guillain Barre syndrome: the role of steroids.

Guillain-Barre Syndrome (GBS) is one of the commonest demyelinating diseases of the peripheral nervous system. This retrospective cohort study reports the outcomes of 97 patients in a large teaching hospital in South India. Fifty patients were treated with steroids and 47 had no steroids. Twenty one of the 41 evaluable patients in the steroid group had functional improvement at discharge as compared to 20 of 42 evaluable patients in the non-steroid group. Six patients in each group had worsening of their weakness. Steroids did not show any significant beneficial effect in either improving the disability scores at discharge (steroid-0.42 vs. non-steroid-0.29) or in reducing the duration of ICU stay (4 vs. 8 median days). A higher proportion of patients on steroids developed complications (p = 0.02). The median duration of hospital stay was 16 days in the steroid group as opposed to 14 days in the group not treated with steroids. The mortality was 6 in the steroid treated group and 5 in the non-steroid group. Steroids have no significant benefit on the outcome of GBS.

Adult↗
PubMed1995

Phenotypic and cell cycle properties of human oligodendrocytes in vitro.

The remyelination, albeit limited, which occurs at the lesion sites in the central nervous in multiple sclerosis has been attributed to both myelin production by previously myelinating cells and to precursor cells which mature into myelin-producing cells. Oligodendrocyte (OL) number may be increased at the periphery of the lesions. In this study, we assessed the state of maturation and cell cycle-dependent properties of OLs derived from surgically resected adult human cerebral cortex specimens. In 6-day-old OL cultures, a small proportion of cells (14.1 +/- 3.5%: range 4-24%) expressed an immature phenotype, defined as A007+:myelin basic protein (MBP)-negative. Using lack of statin expression as an index of cells exiting the G0 phase of the cell cycle, we observed that 4.6 +/- 1.6% of A007+ cells, but only rare MBP+ cells (0.4 +/- 1.8%) were non-reactive with the anti-statin antibody, S44. The proportion of non-statin-reactive cells was not affected by treatment with basic fibroblast growth factor (bFGF), platelet-derived growth factor (PDGF) or insulin-like growth factor (IGF). The oligodendrocytes did not incorporate BrdU during a 48-h pulse and did not immunoreact with Ki-67 antibody. In 4-week-old cultures, we found that all A007+ cells were also MBP+ and that 99.5 +/- 0.7% were statin-positive. Exposing 4-week-old OLs to conditions of serum deprivation or to 1,000 units/ml of recombinant human TNF-beta for 4 days induced nuclear fragmentation in a high proportion (> 70%) of cells, as measured by a TUNEL technique; in these cultures, a similarly high proportion of cells were non-immunoreactive with anti-statin antibody. Our results suggest that a small number of phenotypic 'pre-oligodendrocytes' can be derived from the adult human CNS and that a proportion of these cells have exited the G0 phase of the cell cycle. Attempt at cell cycling, however, could reflect abortive mitosis and activation of programmed cell death.

Cell Cycle↗
PubMed1994

Heat shock protein immunoreactivity in CSF: correlation with oligoclonal banding and demyelinating disease.

The detection of raised immunoglobulin and the presence of oligoclonal bands (OCBs) on electrophoresis of multiple sclerosis (MS) CSF has been a useful diagnostic test, but a universal antigen to which these MS antibodies are directed has yet to be found. Potentially immunogenic heat shock proteins (HSPs) are preferential expressed in vitro in human oligodendrocytes compared with other glia, and in situ in oligodendrocytes found within the plaques of MS. Immunoreactivity directed against HSPs might therefore contribute to the immune-mediated demyelinating process found in MS. We examined this possibility by quantitatively (ELISA) measuring antibodies directed against a recombinant human HSP (HSP60) in CSF from 18 MS patients, and compared them with eight patients with acute disseminated encephalomyelitis, 12 with demyelinating peripheral neuropathies, and 59 with other neurologic diseases. Immunoblotting was used to confirm the specificity of the antibodies for binding to HSP60. We found a statistically significant correlation between antibody titers to HSP60 and the presence of OCBs in CSF. These results support the notion that HSP expression in the CNS, such as that observed in MS, may be immunogenic, leading to localized HSP antibody secretion. Such HSP-directed immunoreactivity could play a role in the pathogenesis of MS and other immune-mediated disorders of the nervous system.

Antibodies↗
PubMed1993

Cerebro-spinal fluid cytomorphology in tuberculous meningitis--a preliminary report.

The morphology of cells in centrifuged cerebrospinal fluid (C.S.F.) of 25 patients with tuberculous meningitis (T.B.M.) in different stages of the illness is presented. Blood brain barrier studies were also done in 6 patients. Maximum variability of cells in the initial stages of the illness and persistence of polymorphs in the later stages of the illness is noted. No correlation was established between cerebrospinal fluid cytomorphology and complications of the illness.

Humans↗
PubMed1993

Demonstration of an apical chloride conductive pathway in granular cells of toad urinary bladder.

Chloride electrodiffusion across the apical membrane of granular cells from toad urinary bladder, an analogue of mammalian principal cells, was examined using the patch clamp technique. A chloride conductance was demonstrated in cell-attached membrane patches exposed to barium chloride pipette solutions. A change in the pipette chloride concentration from 30 to 100 mM caused a shift in the current voltage curve which demonstrated chloride selectivity. The chloride conductance was also examined in excised, inside out membrane patches using choline chloride solutions (chloride:choline selectivity ratio was 18:1). A closed and two open chloride conductive states were found (states A and B, 10.1 +/- 1.0 and 17.2 +/- 5.5 pS, respectively, p < 0.01). Incubation of the preparation with arginine vasopressin, dibutyryl-cAMP, or 8-bromo-cAMP approximately doubled chloride conductance to 16.6 +/- 1.7 pS (p < 0.01). The enhanced electrodiffusion was accounted for by a shift in the channel kinetics from the closed state C to the high conductance state B (p < 0.05, n = 9). 4,4'-Diisothio-cyanatostilbene- 2,2'-disulfonic acid (DIDS) and 9-anthracene-carboxylic acid (9-AC) failed to block the chloride currents. In conclusion, the regulated apical chloride conductance described would balance the sodium and potassium electrodiffusive pathways and maintain a stable membrane potential, facilitating overall conductive transport by these cells.

Animals↗
PubMed1992

Vanishing CT lesions in epilepsy.

Experience with computed tomography (CT) in patients with epilepsy has drawn attention to specific type of cerebral lesions widely prevalent in this part of the world. The lesions disappear spontaneously while patients receive only anticonvulsant therapy. The exact nature of these lesions is not yet understood. One-hundred and twenty-two such patients (M 77; F 45) were studied. Their age ranged from 3 to 57 (mean 21.8 +/- 12.7) years. Seizures were partial motor in 86 (70.5%), generalised tonic clonic in 31 (25.4%), complex partial in 4 and atonic in one case. Postictal hemiparesis was seen in 6 patients who completely recovered within 5 min to 7 days. One hundred patients underwent EEG examination. It was abnormal in 84 cases; 40 patients showed localisation which correlated with CT findings. Plain CT showed low attenuation lesions in all cases. Morphology on contrast enhancement was ring lesion in 50 (40.9%), disc lesion in 47 (38.5%), target lesion in 3 (2.5%), mixed lesion in 2 (0.8%), no enhancement in 18 (14.8%) and a speck with oedema in 2 (0.8%) cases. All lesions were cerebral, present at cortical-subcortical junction. The first follow-up scan was performed in 78 (63.9%) patients within 6-12 weeks. It showed complete disappearance of the lesion in 47 (60.3%) cases. Reduction in size of the lesion and surrounding oedema was observed in 24 (30.8%) cases. The follow-up scans in these 24 cases revealed disappearance of lesion in 11 cases and almost complete resolution of the lesion with a remaining speck in 13 cases. Cerebrospinal fluid (CSF) was normal in 95 out of 100 cases in which it was performed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗