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Biomedical subjects

A N Singh

Publications and source records attributed to A N Singh.

At least 19 recordsLinked to original sources
PubMed2006

Vibrational assignment of the normal modes of 2-phenyl-4-(4-methoxy benzylidene)-2-oxazolin-5-one via FTIR and Raman spectra, and ab inito calculations.

Raman and FTIR spectra of 2-phenyl-4-(4-methoxy benzylidene)-2-oxazolin-5-one were recorded in the regions, 100-3300 and 400-4000 cm(-1), respectively. Vibrational frequencies and intensities of the fundamental modes of this hetrocyclic organic molecule were computed using ab initio as well as AM1 semiempirical molecular orbital methods. Ab initio calculations were carried out with basis set up to RHF/6-311G. Conformational studies regarding the effect of moving the methoxy group in the 2-phenyl-4-(4-methoxy benzylidene)-2-oxazolin-5-one molecule to a different position on the ring was also carried out. Observed vibrational wavenumbers were found to be mostly consistent with ab initio values. The most intense mode of vibration observed at 1250 cm(-1) in Raman spectra, also observed as a strong band in FTIR, was assigned as C-O stretching vibration in the methoxy group. Asymmetric stretching vibrations between CC and CN bonds was predicted as most intense mode by our ab initio calculation.

Benzylidene Compounds↗
PubMed2006

Ab-initio and density functional study of L- and D-forms of alanine and serine in gas phase and bulk aqueous medium.

The molecular geometry of L and D-forms of alanine and serine in gas phase have been studied by using ab-initio quantum chemical calculations at the restricted Hartree-Fock (RHF) level by employing 6-31G and 6-311++G** basis sets. Subsequently, for considering the electron correlations, Density functional Calculations at the Becke3LYP (B3LYP) and Moller-Plesset second order (MP2) level of calculations have been carried out with the same basis sets for these optimized geometries. Effect of solvation in water on the optimized geometries was studied using the polarized continuum model of the self-consistent reaction field (SCRF) theory. The dipole moment, energy, polarizabilities and vibrational frequencies have been calculated in all cases. Frequency analysis was carried out to ensure that optimized geometry corresponds to a total energy minimum.

Alanine↗
PubMed2003

Pericardial synovial sarcoma.

A 29-year-old young man presented with acute breathlessness. After investigative work-up he was found to have a massive pericardial tumour. Thoracotomy and near total surgical excision of the pericardial tumour was carried out. Histopathology and immunohistochemical markers study revealed it to be a synovial sarcoma arising from the left lateral pericardial surface. Postoperatively, he received external radiation and chemotherapy. Thirteen months after surgery he developed local recurrence which was unresectable.

Adult↗
PubMed2001

Inverse agonist binding of peripheral benzodiazepine receptors in anxiety disorder.

The binding characteristics of the pBR (peripheral benzodiazepine receptor) inverse agonist, [3H]-Ro 5-4864, were examined in patients diagnosed as generalized anxiety disorder. As compared to normal healthy controls, the anxious subjects demonstrated a statistically significant (p < 0.001) increase in the density of pBR in platelets. The enhanced pBR binding correlated significantly with the severity of global anxiety symptom of the Hamilton Anxiety Rating Scale (HAR-S, p < 0.001). The Psychic component, but not the Somatic component, of the HAR-S, correlated significantly (p < 0.001) with the enhanced pBR binding in platelets. The results provide evidence for the hypothesis of dysregulation of peripheral benzodiazepine receptors in generalized anxiety disorder.

Adult↗
PubMed2001

Quick start-up and quick steady-state techniques for UAFFB reactor.

Start-up periods of anaerobic reactors need 2 to 3 month to an year (or even more), presumably because of use of non-acclimated anaerobic seed and its slow growth rate. Aerobes commonly excrete glue-like substance such as slime, which aid in attachment of aerobic biofilm to the filter media. The anaerobes do not produce slime and are continuously washed out of reactor. However they attach themselves to slime matrix produced by others (aerobes). The present studies emphasized on initial creation of slime layer on the surfaces of fixed bed media followed by introduction of acclimated anaerobic biomass in bulk, which was expected to get attached to the slime layer, produce biofilm and in turn reduce start-up time. The results are very encouraging and 'Start-up Technique' finalized during these studies is found to be very effective in reducing the start-up period of laboratory scale UAFFB reactor to as low as 15 days even at high organic loading of 5.95 kg COD/day/cum of reactor. The 'Steady-state Technique' is found to be useful in creating the steady-state condition in minimum period of 15 days on increasing the organic loading rate to 7.66 kg COD/day/cum of reactor.

Bacteria, Anaerobic↗
PubMed2000

Drug treatment of HIV associated neuropsychiatric syndromes.

Psychotropic drugs are frequently used to treat the wide range of neuropsychiatric syndromes that patients infected with the human immunodeficiency virus (HIV) may develop. In order to administer these agents properly, physicians should take into account, among other factors, that: the central nervous system (CNS) of these patients is often impaired; they tend to suffer from one or more physical disorders; and they may be taking various other medications. The present paper reviews the clinical features and the general guidelines for administering neuroleptics, antidepressants, psychostimulants, benzodiazepines, opiates, lithium and carbamazepine in this group of patients, based on the literature and the authors' own clinical experience.

HIV Seropositivity↗
PubMed1999

Pharmacotherapy of chronic alcoholism: a review.

Although alcohol has been recognized as an agent of abuse since the 17th century, the disease model was accepted only in the last century. Alcoholism is defined as a chronic and progressive disease characterized by loss of control over the use of alcohol with subsequent social, legal, psychological and ethical consequences. Recently, monoamines were shown to have a predominant role in the etiology of alcoholism. Dopamine has been implicated by virtue of its actions on the reward center. Endogenous opioids which lessen stress and produce euphoria, are released upon alcohol intake, whereas increased serotonin facilitates tolerance and thereby fosters increased alcohol consumption. Alcohol has facilitative effects on inhibitory action of GABA, while the stimulatory effects of glutamate are decreased. Drugs used for treatment of alcohol dependence can be broadly classified into 4 groups: sensitizing drugs, opioid antagonists, drugs acting on serotonergic systems and acamprosate. Disulfiram has been shown to be most effective for patients who believe in its efficacy and remain compliant with the treatment. The opioid antagonist naltrexone lowers relapse rate, reduces drinking days and prolongs periods of abstinence, while serotonin reuptake inhibitors and serotonin antagonists at best have equivocal efficacy. Acamprosate restores the normal activity of glutamate and GABA systems. The treatment of alcoholism should not be restricted to pharmacotherapy alone but should also be supplemented with interventions addressing the psychological, medical and social needs of patients.

Journal Article↗
PubMed1997

Treatment of HIV-related psychotic disorders with risperidone: a series of 21 cases.

We describe a consecutive series of 21 patients with HIV or AIDS who received risperidone for psychotic disorders. Of these, 13 became symptom-free, 7 showed substantial improvement, and 1 had no response. Most responded to low doses of risperidone (mean maximum dose 3.3 mg) and needed only a short course of treatment (mean 6.4 weeks). The 12 manic patients did particularly well: 9 became symptom-free and the mean Young mania rating scale fell from 28.36 to 3.91. No serious adverse effects were reported. Three patients became drowsy and two experienced drooling, but these resolved after dose reductions or at the end of treatment. No adverse hematological effects were observed. We suggest that risperidone may be the treatment of choice for patients with HIV-related psychotic disorders.

Acquired Immunodeficiency Syndrome↗
PubMed1996

A neurochemical basis for the antipsychotic activity of loxapine: interactions with dopamine D1, D2, D4 and serotonin 5-HT2 receptor subtypes.

Loxapine is a typical neuroleptic that shows great structural and functional homology to the atypical antipsychotic clozapine. Chronic loxapine treatment is usually associated with extrapyramidal symptoms (EPS), whereas clozapine treatment is not. Conversely, loxapine does not produce the agranulocytosis that often results from protracted clozapine treatment. Earlier studies of loxapine have usually implicated D2 receptor blockade as the cause of the tardive dyskinesia that occurs with chronic treatment. More recently, loxapine's ability to potentiate serotonergic neurotransmission has also been implicated. In this study, the pharmacological affinities of loxapine for the dopamine D1, D2, D4, as well as serotonin-2 (5-HT2) and NMDA receptor subtypes, were investigated through direct radioreceptor assays. The findings indicate that loxapine displays an extremely strong binding affinity for dopamine D4 and serotonin 5-HT2 receptors, which suggests that both serotonergic and dopaminergic mechanisms contribute to the antipsychotic drug action and EPS associated with loxapine in the treatment of schizophrenia.

Antipsychotic Agents↗
PubMed1994

Experience with amphotericin B in sodium stibogluconate--unresponsive cases of visceral Leishmaniasis in north Bihar.

One hundred cases of Indian Kala-azar unresponsive to sodium stibogluconate (SSG) were treated with amphotericin B. The drug was given in the dose schedule of 0.75 mg/kg body weight on alternate days intravenously dissolved in 5 percent dextrose solution. After 15 infusions given over a period of 30 days, all cases became clinically and parasitologically cured. Mild adverse reactions were noted during therapy. No relapse was observed at follow up after 12 months.

Adolescent↗
PubMed1988

Analysis of the galactosyltransferase reaction by positional isotope exchange and secondary deuterium isotope effects.

The mechanism of the galactosyltransferase-catalyzed reaction was probed using positional isotope exchange, alpha-secondary deuterium isotope effects, and inhibition studies with potential transition state analogs. Incubation of [beta-18O2, alpha beta-18O]UDP-galactose and alpha-lactalbumin with galactosyltransferase from bovine milk did not result in any positional isotope exchange. The addition of 4-deoxy-4-fluoroglucose as a dead-end inhibitor did not induce any detectable positional isotope exchange. alpha-Secondary deuterium isotope effects of 1.21 +/- 0.04 on Vmax and 1.05 +/- 0.04 on Vmax/KM were observed for [1-2H]-UDP-galactose. D-Glucono-1,5-lactone, D-galactono-1,4-lactone, D-galactono-1,5-lactone, nojirimycin, and deoxynojirimycin, did not inhibit the galactosyl transfer reaction at concentrations less than 1.0 mM. The magnitude of the secondary deuterium isotope effect supports a mechanism in which the anomeric carbon of the galactosyl moiety has substantial sp2 character in the transition state. Therefore, the cleavage of the bond between the galactose and UDP moieties in the transition state has proceeded to a much greater extent than the formation of the bond between the galactose and the incoming glucose. The lack of a positional isotope exchange reaction indicates that the beta-phosphoryl group of the UDP is not free to rotate in the absence of an acceptor substrate.

Animals↗
PubMed1988

The mechanism of glycogen synthetase as determined by deuterium isotope effects and positional isotope exchange experiments.

The reaction mechanism for glycogen synthetase from rabbit muscle was examined by alpha-secondary deuterium isotope effects and positional exchange experiments. Incubation of glycogen synthetase with [beta-18O2,alpha beta-18O]UDP-Glc did not result in any detectable positional isotope exchange from the beta-nonbridge position to the anomeric oxygen of the glucose moiety. Glucono-1,5-lactone was found to be a noncompetitive inhibitor versus UDP-Glc. The kinetic constants, K(is) and K(ii), were found to be 91 +/- 4 microM and 0.70 +/- 0.09 mM, respectively. Deoxynojirimycin was a nonlinear inhibitor at pH 7.5. The alpha-secondary deuterium isotope effects were measured with [1-2H]UDP-Glc by the direct comparison method. The isotope effects on Vmax and Vmax/K were found to be 1.23 +/- 0.04 and 1.09 +/- 0.06, respectively. The inhibitory effects by glucono-lactone and deoxynojirimycon plus the large alpha-secondary isotope effect on Vmax have been interpreted to show that an oxocarbonium ion is an intermediate in this reaction mechanism. The lack of a detectable positional isotope exchange reaction in the absence of glycogen suggests the formation of a rigid tight ion pair between UDP and the oxocarbonium ion intermediate.

Animals↗
PubMed1988

A double blind comparison of alprazolam and amitriptyline hydrochloride in the treatment of nonpsychotic depression.

In a six week, double-blind, parallel study of alprazolam and amitriptyline hydrochloride in 130 outpatients suffering from moderate to severe nonpsychotic depression, alprazolam was as effective as amitriptyline hydrochloride in relieving depressive symptoms and significantly more effective in relieving symptoms of anxiety and somatization. Alprazolam showed an earlier onset of activity in most measurements of efficacy and produced fewer side effects than amitriptyline hydrochloride. Anticholinergic side effects were reported more frequently by patients taking amitriptyline hydrochloride, while drowsiness was reported more frequently by patients taking alprazolam. At the end of the study, the average daily doses were 2.4 mg alprazolam and 135 mg amitriptyline hydrochloride. The Hamilton Psychiatric Rating Scale for Depression, Hamilton Anxiety Rating Scale, Physician's Global Impressions, Patients' Global Impressions, Hopkins Self-Rating Symptom Scale, and Symptom and Side Effects Checklist were evaluated at the end of weeks 1, 2, 3 and 6 to determine and compare the efficacy and safety of the two study drugs.

Adult↗