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Biomedical subjects

R Tandon

Publications and source records attributed to R Tandon.

At least 73 records · Page 4Linked to original sources
PubMed2000

Comparison of central and peripheral pharmacologic effects of biperiden and trihexyphenidyl in human volunteers.

In this double-blind, randomized study, indices of central (memory, sedation) and peripheral (salivation, ratio of R-R interval on electrocardiogram) muscarinic function were evaluated in 14 healthy volunteers who received trihexyphenidyl, biperiden, and placebo. Additionally, serum drug levels were obtained 2 hours after oral administration. All subjects participated in three study sessions. During each session, subjects received two doses of biperiden (4 mg), trihexyphenidyl (5 mg), or placebo, and four series of tests were administered. The tests included the determination of cardiac response to standing (R-R ratio), mouth salivation, finger-tapping speed, digit span (forward and backward), a selective reminding task, and visual analog scales (VAS). On the VAS, subjects rated biperiden as significantly more sedating than either trihexyphenidyl or placebo, and both biperiden and trihexyphenidyl were associated with more dizziness than was placebo. Saliva production was significantly reduced by both trihexyphenidyl and biperiden compared with placebo. Digit span performance was significantly decreased in only the backward direction. The selective reminding task revealed highly significant decrements in the number of words recalled and consistent long-term retrieval after both biperiden and trihexyphenidyl. Delayed recall was significantly decreased by both active drugs. Both trihexyphenidyl and biperiden caused a significant increase in the R-R ratio comparison with placebo. With the exception of the VAS measurement of sedation, the effects caused by biperiden and trihexyphenidyl did not differ. The results of this study do not support the hypothesis that the side effect profile of biperiden is significantly different from that of trihexyphenidyl.

Adolescent↗
PubMed2000

Cysticercosis of the optic nerve.

Cysticercosis of the optic nerve has been reported only twice in the literature. A case of optic nerve cysticercosis in a 50-year-old woman with atypical optic neuritis is reported. Computerized tomography showed a thickened left optic nerve with a ring-enhancing lesion containing an eccentric nodule. An enzyme-linked immunosorbent assay test for cysticercosis further established the diagnosis. The patient was treated with oral prednisolone and albendazole, with no improvement in vision.

Albendazole↗
PubMed2000

Stevens-Johnson syndrome in India - risk factors, ocular manifestations and management.

We conducted a study to analyse the presentation, risk factors, ocular manifestations and ophthalmic management results of Stevens-Johnson syndrome (SJS) in Indian patients. A total of 20 patients with SJS with ocular involvement were studied. Female predominance (70%) was observed. The age ranged from 10 to 30 years (mean +/- SD: 16.85 +/- 5.96). The commonest precipitating risk factor was oral drug intake (80%), sulphonamide (30%; sulphamethoxazole-trimethoprim) being the commonest. One patient had reaction to ciprofloxacin which has not been reported previously. Four patients (20%) had spontaneous onset with no identifiable risk factor. None of the patients had specific infection per se as a risk factor. Conjunctival involvement and its sequelae were the major ocular manifestations. At presentation, the majority of the eyes (68%) had visual acuity less than 3/60. Despite appropriate medical treatment and surgical interventions (11 eyes; 28%) vision continued to deteriorate. In 1 eye, the vision improved after stem cell transplantation. Therapeutic penetrating keratoplasty could preserve ocular integrity in 1 patient.

Adolescent↗
PubMed1999

Landmark-based morphometric analysis of first-episode schizophrenia.

BACKGROUND: The goal of this investigation was to utilize landmark-based shape analysis and image averaging to determine the sites and extent of specific structural changes in first-episode schizophrenia. METHODS: Neuroanatomic structures identified on midsagittal magnetic resonance imaging (MRI) scans were compared between 20 patients with schizophrenia and 22 normal control subjects. The difference between averaged landmark configurations in the two groups was visualized as a shape deformation by a thin-plate spline and through averaged MRI images for both groups. RESULTS: A shape difference was found to be statistically significant; by inspection, it is contrast between differences in two closely abutting regions, involving primarily the posterior corpus callosum and upper brain stem--the "focus" is the relation between them. CONCLUSIONS: The findings are consistent with prior studies suggesting involvement in schizophrenia of the corpus callosum and the limbic structures contributing to the corpus callosum; the possibility of local pathology primarily involving the brain stem cannot be excluded. The methods of landmark-based shape analysis and image averaging utilized in this study can complement the "region-of-interest" method of investigating morphometric abnormalities by characterizing the spatial relationships among structural brain abnormalities in schizophrenia.

Adolescent↗
PubMed1999

Crack Arrest and Multiple Cracking in Glass Through the Use of Designed Residual Stress Profiles.

A processing approach has been identified and reduced to practice in which a residual stress profile can be designed such that cracks in a brittle material are arrested or grow in a stable manner. In the approach, cracks in the body encounter an increase in the magnitude of residual compression as the crack propagates. If correctly designed, the process increases strength and significantly decreases strength variability. This approach was demonstrated for a silicate glass, and multiple cracking was observed as a forewarning of the final failure. Normally, such glasses would fail catastrophically with the propagation of a dominant crack.

Journal Article↗
PubMed1999

Hemoglobin endocytosis in Leishmania is mediated through a 46-kDa protein located in the flagellar pocket.

Four lines of evidence indicate that a specific high affinity binding site on the surface of Leishmania donovani promastigotes mediates rapid internalization and degradation of hemoglobin. 1) Binding and uptake of 125I-hemoglobin by Leishmania followed saturation kinetics and were competed by unlabeled hemoglobin but not by globin or hemin or other heme- or iron-containing proteins. 2) Immunogold labeling studies revealed that, at 4 degreesC, hemoglobin binding was localized in the flagellar pocket of the promastigotes. Indirect immunofluorescence assays showed that, at 37 degreesC, the bound hemoglobin in such cells entered an endocytic compartment within 2 min and dispersed throughout the cell body by 15 min. 3) After incubation with hemoglobin-gold conjugates at 25 degreesC or 37 degreesC, the particles accumulated in discrete intracellular vesicles. 4) A single biotinylated protein of 46 kDa was revealed when solubilized membranes from surface biotinylated intact Leishmania adsorbed by hemoglobin-agarose beads were subjected to SDS-polyacrylamide gel electrophoresis and Western blotting with avidin-horseradish peroxidase. Considered together, these data indicate that this 46-kDa protein on the cell surface of L. donovani promastigotes mediates the binding of hemoglobin and its rapid internalization through a vesicular pathway characteristic of receptor-mediated endocytosis.

Animals↗
PubMed1999

Sequential production of cytokines by dengue virus-infected human peripheral blood leukocyte cultures.

The study was undertaken to elucidate the sequence of appearance of T helper (Th)1- and Th2-type cytokines in human peripheral blood leucocyte cultures infected in vitro with dengue type 2 virus. Commercial sandwich enzyme-linked immunosorbent assay kits were used to assay the levels of tumour necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), interleukin (IL)-2, IL-4, IL-5, IL-6, and IL-10 in culture supernatants. Culture supernatants were also screened for the cytotoxic factor and the dengue virus titres determined. The cytokines that appeared in the culture supernatants on the first day post-infection (p.i.) were cytotoxic factor, TNF-alpha, IL-2, and IL-6; their levels were highest on the second day p.i. IFN-gamma appeared on the second day with a peak on the third day p.i. The levels of these cytokines declined quickly, except for human cytotoxic factor (hCF) and IL-2. The cytokines that appeared later were IL-10 and IL-5 on the fourth day and IL-4 on the sixth day p.i. Dengue virus replicated in the peripheral blood leucocyte (PBL) cultures and was present throughout the course of the study. The findings of the present study show that dengue virus induced a predominant Th1-type cytokine response during the first 3 days of infection of PBL cultures that was replaced by a Th2-type response later.

Animals↗
PubMed1999

Combined electroconvulsive therapy and clozapine in treatment-resistant schizophrenia.

1. To assess the efficacy and safety of combining electroconvulsive therapy (ECT) and clozapine in patients with treatment-resistant schizophrenia, the authors reviewed use of this combination in four treatment-resistant schizophrenic inpatients and one inpatient with schizophrenia who was intolerant of clozapine doses needed to control her psychosis. 2. The combination of clozapine and bilateral ECT was modestly effective in two treatment-resistant patients and markedly effective in three patients. There was significant overall improvement in patients' Clinical Global Impression (CGI) and Global Assessment of Functioning (GAF) scores (p < 0.005 and p < 0.0004, respectively), however in patients where marked symptomatic improvement was noted, effects were not sustained. 3. One of the patients that showed dramatic yet transient improvement followed by relapses received maintenance ECT but relapsed despite this. 4. The authors saw no adverse effects in connection with the combination of ECT and clozapine. 5. Supplementing clozapine with a course of bilateral ECT appears to be safe and is effective in some patients with refractory schizophrenia, however its beneficial effects may be short-lived. The long-term impact of ECT on the course of schizophrenia in patients incompletely responsive to clozapine is not fully elucidated.

Adult↗
PubMed1999

Global cerebral blood flow increase reveals focal hypoperfusion in schizophrenia.

Recent functional neuroimaging strategies have evaluated cerebral blood flow (CBF) to determine specific sites of action of pharmacologic agents. Since many pharmacologic agents change global CBF, we investigated the effects of global CBF changes on regional perfusion with acetazolamide, which increases global CBF via non-neuronal mechanisms. We used the [15O]PET technique to measure CBF before and after we infused 8 schizophrenic patients and 10 healthy control subjects with acetazolamide. The rostral anterior cingulate cortex demonstrated a greater perfusion increase in the schizophrenic subjects after acetazolamide infusion, relative to other areas of the brain. During the baseline condition, this area showed relative hypoperfusion in our sample of schizophrenic subjects, consistent with previous functional neuroimaging studies. The results demonstrate the need for caution in interpreting CBF changes after pharmacologic challenge, because global CBF changes can confound the assessment of regionally-specific pharmacologic action.

Acetazolamide↗
PubMed1999

Retrobulbar optic nerve cysticercosis with surgical removal: a case report.

A 15-year-old boy presented with diminution of vision which rapidly progressed to no perception of light. In the ocular fundus, a neuroretinitis-like picture was seen. On CT-scan & ultrasonography, an optic nerve swelling was detected with a shadow of scolex. Medical therapy in the form of steroids along with albendazole was ineffective. Surgical removal by lateral orbitotomy was done and a complete cyst with scolex was removed, which was confirmed histopathologically as a case of retrobulbar optic nerve cysticercosis.

Journal Article↗
PubMed1999

Cholinergic aspects of schizophrenia.

While increased dopamine activity is central to our current understanding of the pathophysiology of schizophrenia, dysregulation of a single neurotransmitter is unlikely to explain the disorder adequately. It is argued here that the muscarinic aspects of schizophrenia should be reassessed for a number of reasons. These include current evidence that cholinergic modulation affects both positive and negative symptoms, and neuroendocrine and polysomnographic data that suggest an increased muscarinic cholinergic activity in schizophrenia. In addition, the interactions between the dopaminergic and cholinergic systems are becoming better understood and appear to occur especially in regions that are thought to be relevant is schizophrenia. The fact that the highest affinity of clozapine, with its unique therapeutic profile, is to the muscarinic receptor encourages further evaluation. Finally, the use of anticholinergic agents to treat extrapyramidal side-effects and the fact that many antipsychotic agents have intrinsic anticholinergic activity suggest that the role of the cholinergic system in schizophrenia needs to be more clearly delineated.

Antipsychotic Agents↗
PubMed1999

Antipsychotics from theory to practice: integrating clinical and basic data.

The recent introduction of the atypical antipsychotics into the treatment arena for psychoses and related disorders comes with justifiable excitement. These newer antipsychotics offer several clinical benefits over the conventional antipsychotics, which have been the mainstays of care thus far. The primary advantage of these atypical agents is their superior side effect profiles, particularly with regard to extrapyramidal side effects (EPS). The implications from a reduction in EPS touch on virtually every aspect of pathology in schizophrenic illness, including short- and long-term movement disorders, negative symptoms, noncompliance, cognitive dysfunction, and dysphoria. It should be emphasized that while atypical antipsychotics share many clinical attributes, there are also substantial differences among them. This review will examine the pharmacology, clinical efficacy, and side effect profiles of the atypical antipsychotics and attempt to relate the attributes observed in clinical practice and clinical trials to their basic pharmacologic profiles. There is a fair, but not perfect, correspondence between the pharmacologic profiles of the different atypical antipsychotics and their respective clinical attributes. After a comparative overview of their receptor-binding profiles, a brief pharmacokinetic summary will be provided. Finally, the clinical profiles of these agents will be summarized with regard to both their efficacy and adverse effects.

Animals↗
PubMed1999

The efficacy, safety, and tolerability of antipsychotics in the elderly.

Antipsychotic medications are among the most widely prescribed class of medications for elderly patients. Despite their high use, few studies document the efficacy, safety, and tolerability of these agents in this patient population. This is unfortunate because, as a group, the elderly are exceptionally sensitive to the adverse effects associated with antipsychotics, in particular, the extrapyramidal side effects (EPS). The atypical antipsychotics with their lower propensity to cause EPS and lower need for augmenting anticholinergic medication have introduced new options for elderly patients who need antipsychotic therapy for a number of psychiatric and neurologic disorders with psychotic manifestations. This review covers the pharmacologic, clinical, and regulatory issues involving antipsychotic use in elderly patients that warrant consideration by the practicing psychiatrist.

Accidental Falls↗