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Biomedical subjects

S Prabhakar

Publications and source records attributed to S Prabhakar.

At least 109 records · Page 6Linked to original sources
PubMed1999

Primary progressive aphasia : a case report.

Primary progressive aphasia is due to focal left perisylvian degeneration and manifests with progressive decline in language function for two or more years. There is preservation of cognitive functions and activities of daily living continue to be normal. We report a case of progressive aphasia in a 65 year old lady.

Aged↗
PubMed1999

Ischaemic stroke: new frontiers.

Lot of advancement has taken place, not only in the management but also in the pathophysiology and imaging modalities in patients of stroke. Indolent chronic infections, particularly those due to H. pylori, have been identified as one of the risk factors. The mechanism of inflammation in inducing a precoagulant state has also been worked out. SPECT studies have detected ischaemic areas before appearance of CT abnormalities. CT angiography identifies abnormalities in the 'circle of willis' in posterior circulation strokes much better, and helps weigh the risk versus benefit of thrombolysis. With experiance in use of r-TPA, the list of contra indications and precautions has become longer than its indications. Newer drugs like lubeluzole and edselen have also been recommended. Various other drugs e.g. aptiganel hydrochloride, MDL 28170, 'basic fibroblast growth factor' and 'superoxide dismutase' are at an experimental stage. The concept of a 'stroke cocktail' may be in vogue soon. Controversies still exit regarding the exact indication of prophylactic anticoagulant and the 'international normalized ratio' (INR) to be achieved. Guidelines have been laid down for the approach to patients with asymptomatic carotid artery stenosis. However, the paramount message in stroke care is dissipation of the concept of 'brain attack', amongst the primary care medical and para-medical personnel.

Brain Ischemia↗
PubMed1999

Botulinum toxin treatment of hemifacial spasm and blepharospasm: objective response evaluation.

Twenty seven patients with hemifacial spasm (HFS) and sixteen patients with blepharospasm (BS) having mean Jankovic disability rating scale score of 2.56+0.58 SD and 2.81+0.54 SD, respectively, were treated with botulinum toxin A (BTX-A) injections. The total number of injection sessions were ninety one with relief response in 98.91%. The mean improvement in function scale score was 3.78+0.64 SD and 3.29+1.07 SD respectively, in HFS and BS groups. The clinical benefit induced by botulinum toxin lasted for a mean of 4.46+3.11 SD (range 2 to 13) months in HFS group and 2.66+1.37 SD (range 1 to 6) months, in BS groups. Transient ptosis was seen in 4.39% of total ninety one injection sessions. These findings show that local botulinum toxin treatment provides effective, safe and long lasting relief of spasms.

Adult↗
PubMed1999

Genetic polymorphism in muscle biopsies of Duchenne and Becker muscular dystrophy patients.

Duchenne muscular dystrophy (DMD), with an incidence of one in 3500 male new borns, and its milder variant, Becker muscular dystrophy (BMD), are allelic X-linked recessive disorders, caused by mutations in the gene coding for dystrophin, a 427 kD cytoskeleton protein. There are no available molecular markers to differentiate these two. The purpose of this study was to study genetic polymorphism in muscular dystrophy and explore its potential in discriminating these two allelic forms of the disease. The results revealed unambiguously the presence of three transcripts : 598bp, 849bp and 1583bp long which are selectively expressed in the muscles afflicted with muscular dystrophy as compared to the normal muscle. 1583bp gene transcript was conspicuously present in the muscle tissues of both DMD and BMD patients whereas 598bp and 849bp long transcripts were exclusively present in DMD but not in BMD patients or normal human subjects. These gene transcripts had no sequence homology with dystrophin gene and these were also present in the families belonging to DMD and BMD patients. These results point to the fact that based upon the selective expression of these three gene transcripts, one could not only differentiate between DMD and BMD diseases at the molecular level, but also between normal and dystrophic muscle. Further, these findings also reveal that apart from dystrophin gene, these gene transcripts may also be responsible for the differential progression of DMD/BMD phenotype.

Biopsy↗
PubMed1999

Frequency and factors associated with cardiomyopathy in patients with human immunodeficiency virus infection in an inner-city hospital.

The frequency and factors associated with cardiomyopathy were studied among inner-city hospital patients with human immunodeficiency virus (HIV) infection. Of 84 patients with HIV infection, 20 (24%) had cardiomyopathy. Fourteen (70%) of the patients with cardiomyopathy did not have clinical evidence of congestive heart failure. There was no significant association between cardiomyopathy and common opportunistic infections or zidovudine treatment. These results indicate that cardiomyopathy is common in patients with HIV infection and often is clinically unsuspected.

AIDS-Related Opportunistic Infections↗
PubMed1999

Non-compressive myelopathy: clinical and radiological study.

Fifty seven patients (42 males and 15 females) with non-compressive myelopathy were studied from 1997 to 1999. Acute transverse myelitis (ATM) was the commonest (31) followed by Vit B12 deficiency myelopathy (8), primary progressive multiple sclerosis (5), hereditary spastic paraplegia (3), tropical spastic paraplegia (2), subacute necrotising myelitis (1), radiation myelitis (1), syphilitic myelitis (1) and herpes zoster myelitis (1). 4 cases remained unclassified. In the ATM group, mean age was 30.35 years, antecedent event was observed in 41.9% case, 25 cases had symmetrical involvement and most of the cases had severe deficit at onset. CSF study carried out in 23 patients of ATM revealed rise in proteins (mean 147.95mg%, range 20-1200 mg/dL) and pleocytosis (mean 20.78/cumm, range 0-200 mm3). Oligoclonal band (OCB) was present in 28% of cases of ATM. The most common abnormality detected was a multisegment hyperintense lesion on T2W images, that occupied the central area on cross section. In 6 patients hyperintense signal was eccentric in location. MRI was normal in 4 cases of ATM. Thus ATM is the leading cause of non-compressive myelopathy. Clinical features combined with MRI findings are helpful in defining the cause of ATM.

Adolescent↗
PubMed1999

Lack of pharmacokinetic interaction between grapefruit juice and phenytoin in healthy male volunteers and epileptic patients.

The present study was undertaken to determine the effects of grapefruit juice (GFJ) on the oral bioavailability of phenytoin (DPH). Ten healthy male volunteers received a single dose of 300 mg of DPH orally with 300 ml of water or fresh GFJ in a randomized crossover fashion. In both instances, blood sampling was done at 0, 0.5, 1, 2, 4, 6, 9, 12, 24, 48, 72, 96 and 120 h. The study was also carried out in 10 epileptic patients with uncontrolled seizures even after 3 to 4 weeks regular therapy of DPH (100 mg three times a day). Blood samples were drawn at 0, 1, 2, 3, 4, 5, 6 and 8 h after DPH with 300 ml of water or fresh GFJ. No significant difference was observed in any of the pharmacokinetic parameters like Cmax, Cmin, Tmax, t1/2a, t1/2e and AUC of DPH after GFJ administration as compared to control values in healthy volunteers and epileptic patients. It is concluded that GFJ does not affect the oral bioavailability of DPH.

Adult↗
PubMed1998

Uncommon presentations of neurocysticercosis.

Neurocysticercosis commonly presents with seizures, raised intracranial tension and dementia. The unusual location of the cysts may result in uncommon manifestations mimicking a host of neurological disorders. Ten patients with neurocysticercosis with rare clinical presentations have been described in this series. These include dorsal midbrain syndrome, isolated bilateral ptosis, papillitis, cerebral hemorrhage, painful cervical radiculopathy, progressive swelling of arm, paraplegia due to intramedullary cyst, third ventricular cyst, dystonia and nominal aphasia masquerading as transient ischaemic attacks. The clinical details and possible mechanisms for these rare presentations are discussed.

Adolescent↗
PubMed1998

Identification of an immunogenic histone-like protein (HLPMt) of Mycobacterium tuberculosis.

We report the identification of the first histone-like protein of Mycobacterium tuberculosis (MTB) (HLPMt). The T cell blot assay was used to identify antigens of MTB associated with human immune response in healthy contacts. Fraction 21 corresponding to proteins in the molecular weight range of approximately 30 kDa were found to be immunogenic in tuberculin reactors. None of the fractions were found to be immunogenic by this assay in non-reactors to tuberculin. All sera, irrespective of the source, showed reactivity with MTB antigen(s) over a wide molecular weight range (205-->16 kDa). In the present study fraction 21 was processed for the generation of murine polyclonal sera and amino acid sequencing. The sequence of a 16-amino acid long peptide showed a 100% homology with an open reading frame (ORF) in the translated sequence of cosmid cY349 (Sanger Centre, Cambridge, UK). The ORF was predicted to code for a protein of 214 amino acids. Oligonucleotide primers were synthesized based on the nucleotide sequence located at the 5' and 3' regions of the gene. The gene encoding the predicted protein was PCR-amplified, cloned, sequenced and expressed in Escherichia coli as a protein of 28 kDa. The expressed HLPMt protein was shown to react with the polyclonal murine sera originally raised against fraction 21. Human immune response to the recombinant HLPMt protein was demonstrated by its ability to induce lymphoproliferation in peripheral blood derived mononuclear cells, and the presence of anti-HLPMt antibodies in pooled patient sera by immunoblot. The recombinant HLPMt protein elicited a vigorous lymphoproliferative response especially in healthy tuberculin reactors compared to non-reactors and patients of tuberculosis, (P < 0.05). The protein has unique dual domains with homology to both bacterial histone-like proteins (HU) and eukaryotic histone H1. Homology to prokaryotic and eukaryotic deoxyribonucleic acid (DNA)-binding proteins suggested that HLPMt could bind DNA. DNA-binding properties were confirmed by South-Western analysis strongly suggesting an interaction between HLPMt and the MTB chromosome.

Amino Acid Sequence↗
PubMed1998

Post lumbar puncture headache: is bed rest essential?

Headache following lumbar puncture is a well known and well described complication. Various manoeuvres have been tried to prevent post lumbar puncture headache--the commonest being bed rest for 4 to 24 hours following lumbar puncture, though its value is questionable. Randomised controlled clinical trial was done to evaluate the effect of 24 hours bed rest on the incidence and severity of post lumbar puncture headaches. Two hundred and eight patients were randomly allocated to either the ambulant or the bed rest group. Patients were interviewed by a single investigator on days 0, 1, 2 and 7 about the presence and nature of headache. Other relevant clinical and laboratory data pertaining to the lumbar puncture was collected. The overall incidence of post lumbar puncture headache was 17%; 15% in the ambulant and 18% in the bed rest group. Of the patients who had headaches, severe headache was observed in 57% in the ambulant and 12% in the bed rest group (p = 0.02). Other variables did not alter the outcome of headaches. Bed rest does not appear to alter the incidence of post lumbar puncture headaches, but reduces the severity in those who get headaches, after a lumbar puncture.

Adolescent↗
PubMed1998

Unusual manifestations of thalamic strokes.

Four patients of thalamic strokes with different symptoms are reported. The first had thalamic haemorrhage and developed delayed blepharospasm. The second patient had occlusion of posterior cerebral artery causing infarction of lateral thalamus and occipital lobes. The remaining two patients exhibited ipsilateral hemisensory loss and hemiataxia in absence of hemiparesis (thalamic ataxia). Both had circumscribed lesions in lateral thalamus. 'Thalamic ataxia' has a distinct localizing value. Thalamic strokes produce heterogenous clinical manifestations attributed to the involvement of different nuclei.

Adult↗
PubMed1997

Beta-amyloid and ionophore A23187 evoke tau hyperphosphorylation by distinct intracellular pathways: differential involvement of the calpain/protein kinase C system.

SH-SY-5Y human neuroblastoma cells were treated with 22 microM of a synthetic peptide corresponding to amino acid residues 25-35 of beta-amyloid (betaA) or 3 microM calcium ionophore A23187 in culture medium containing 1.8 mM extracellular calcium. Both agents increased tau immunoreactivity towards antibodies (PHF-1, ALZ-50) that recognize epitopes common with paired helical filaments (PHFs) and towards an antibody (5E2) that recognized a phosphate-independent tau epitope. However, only ionophore increased immunoreactivity with an additional phosphate-dependent antibody (AT-8) that recognized an epitope of tau when phosphorylated, and induced a corresponding decrease in immunoreactivity towards an additional antibody (Tau-1) that recognizes the same site when that site is not phosphorylated. Moreover, the ionophore-mediated increase in PHF-1 was blocked by EGTA, by the calpain inhibitor calpeptin and by the PKC inhibitor H7, while that evoked by betaA treatment was not inhibited by any of these treatments. Since ionophore-mediated calpain activation induces proteolytic PKC activation, we further examined the influence of PKC inhibition on betaA and ionophore-mediated PHF-1 induction. Antisense oligonucleotide-mediated downregulation of PKCepsilon in a stable transfectant SH-SY-5Y subclone diminished the ionophore-mediated, but not the betaA-mediated, increase in PHF-1 immunoreactivity. These data indicate specific differences in the intracellular cascade of events invoked by betaA and ionophore A23187. Moreover, although betaA invoked calcium influx in these cells, our findings further suggest that the induction of tau hyperphosphorylation by betaA may not be due to calcium influx.

Amyloid beta-Peptides↗
PubMed1997

Identification of nitric oxide-sensitive and -insensitive forms of cytoplasmic guanylate cyclase.

Cytoplasmic, nitric oxide-activated guanylate cyclases are expressed in many regions of the mammalian brain and are thought to participate in functions as diverse as synaptogenesis and long-term potentiation. In this study, we have characterized cytoplasmic guanylate cyclases in the nervous system of an invertebrate, the American lobster. Cytoplasmic cyclase specific activity is higher in lobster nerve cord than in any other lobster tissue tested, and considerably higher than in typical rat tissues (cerebellum, lung, and liver). However, nitric oxide donors have minimal effects on lobster nerve cord cyclic GMP production, when applied either to intact tissue or to cytoplasmic extracts. Parallel immunocytochemical studies, using an anti-cyclic GMP antibody, reveal that only a small subset of lobster neurons responds to nitric oxide with a significant elevation of cyclic GMP levels. HPLC analysis of nerve cord cytoplasm reveals two chromatographically separable cyclases, a minor nitric oxide-sensitive form whose retention time is identical to that of the conventional mammalian enzyme and a more abundant nitric oxide-insensitive form that appears to be novel. The physiological function and phylogenetic distribution of this nitric oxide-insensitive enzyme, and the signaling mechanisms that regulate its activity, are not known.

Animals↗