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Biomedical subjects

S P Gupta

Publications and source records attributed to S P Gupta.

At least 19 recordsLinked to original sources
PubMed1992

Quantitative structure-activity relationship studies on benzodiazepine receptor binding: recognition of active sites in receptor and modelling of interaction.

A quantitative structure-activity relationship study was carried out for the binding of a series of 'classical' benzodiazepines (BZs) and some beta-carbolines with BZ receptors to investigate the active sites in the latter and the nature of the binding of compounds with them. Using the Hansch approach, an attempt was made to correlate binding affinities of compounds with various physico-chemical and electronic properties of substituents. The correlations obtained showed the main roles were played by the hydrophobic constant pi and the Hammett constant sigma (an electronic parameter) of various substituents. This led to the suggestion that BZ receptors have many additional hydrophobic, hydrogen bonding and polar sites other than those suggested by Hollinshead et al. (1990). From the present study, the Hollinshead model of interaction was found to be inadequate to account fully for the binding of all types of compounds.

Benzodiazepines↗
PubMed1992

Management of childhood femoral neck fractures.

Forty-three children with displaced transcervical femoral fractures were reviewed at a mean follow-up of 7.2 years and results were assessed using Ratliff's criteria. Of 22 patients treated by internal fixation alone, 10 had good, 6 had fair and 6 had poor results. The results in 21 children treated by internal fixation along with primary transverse intertrochanteric undisplaced osteotomy were: 14 good, 5 fair and 2 poor, but none improved to a statistically significant level (P = 0.139). However, the osteotomy improved the fracture union significantly and no delayed union or non-union was noted in this group (P = 0.05). There were no complications related to the osteotomy itself.

Adolescent↗
PubMed1992

An unusual presentation of oesophageal tuberculosis.

Oesophageal tuberculosis secondary to tuberculous mediastinal lymphadenopathy is a very unusual presentation of adult tuberculosis. We report a young patient who presented with anorexia and weight loss. The chest radiograph and CT scan revealed mediastinal lymphadenopathy causing extrinsic oesophageal compression on the barium swallow. This was confirmed by upper gastrointestinal endoscopy. Four weeks later, because of spontaneous partial relief in dysphagia, upper gastrointestinal endoscopy was repeated and revealed an ulcerated lesion with nodular margins at the mid-oesophagus. Biopsy from the ulcer margin revealed non-caseating granulomas. The patient had complete relief of dysphagia and other symptoms within 3 weeks of start of antituberculosis therapy.

Adult↗
PubMed1991

QSAR studies on benzodiazepine receptor binding of purines and amino acid derivatives.

Quantitative structure-activity relationship (QSAR) studies are reported on the benzodiazepine receptor binding of a series of substituted 9-benzyl-6-dimethylamino-9H-purines and N-(indol-3-ylglyoxylyl)amino acid derivatives. The nitrogen of the five membered heterocyclic ring and the polar substituent in the aromatic ring, present in both series of compounds, form important centres in the binding interaction. We conclude that the receptor must possess a strong nucleophilic centre and a polar site, and that a hydrophobic pocket exists to accommodate hydrophobic moieties.

Algorithms↗
PubMed1990

Quantitative structure-activity relationship study on some 5-lipoxygenase inhibitors.

A quantitative structure-activity relationship (QSAR) study has been made on some lipoxygenase inhibitors belonging to the series of omega-phenylalkyl hydroxamic acids, omega-naphthylalkyl hydroxamic acids, eicosatetraenoic acids, and 1H.benzimidazole-4-ols. It was found that the hydrophobic character of the molecules and the size of their substituents selectively govern their lipoxygenase inhibitory activity. The enzyme active site possesses a non-heme ferric ion, a hydrophobic domain, and a carboxylic acid binding site. It was found that while the functional group of inhibitors must interact with the ferric ion, the substituent on one side of it would be involved in hydrophobic interaction and that on the other side in van der Waals interaction with the enzyme so leading to an enhancement in the inhibitory activity of the inhibitors.

Animals↗
PubMed1990

A quantitative structure-activity relationship study on the inhibitory effects of local anesthetics on sodium flux, phosphoinositide breakdown, and binding to sodium channels.

The inhibitory effects of a series of nonspecific local anesthetics on batrachotoxin-elicited sodium flux, batrachotoxin-elicited phosphoinositide breakdown, and on the binding of [3H]batrachotoxin-A 20 alpha-benzoate to sodium channels in guinea pig cerebral cortical synaptoneurosomes are shown to be well-correlated with the molecular size and the hydrophobic character of the molecules. These correlations lead us to suggest that the drug-receptor interaction involves a dispersion interaction, and that the overall effects of local anesthetics is dependent upon their ability to reach the receptor site.

Anesthetics, Local↗
PubMed1990

Quantitative structure-activity relationships of salicylamide neuroleptic agents.

The in vitro antidopamine activity of substituted N-[(1-alkyl-2-pyrrolidinyl)methyl]-6-methoxysalicylamides was found to be well correlated with the hydrophobic and electronic nature of substituents at the 3-position, and with the steric nature of groups replacing the hydrogen atom of the salicyl hydroxy group. In contrast, only the hydrophobic and steric characteristics were found to be important in the in vivo activity of these neuroleptics. This difference suggests that different mechanisms are probably involved in their in vitro and in vivo actions, and that the relevant receptors are slightly different in structure. The in vitro results suggest that electron donation by the 3-substituent strengthens the formation of a hydrogen bond between the carbonyl group of the amide moiety and a hydrogen of the receptor.

Animals↗
PubMed1990

Tibial condylar fractures treated with traction and early mobilisation (report on study of 75 cases).

Seventy-five cases of tibial condylar fractures irrespective of type of fractures were treated on a purely conservative line of management, consisting of traction and early mobilisation. The follow-up ranged from 6 months to 10 years; 67 cases had satisfactory results. Causes of unsatisfactory results were stiff knee, flexion deformity, osteo-arthritis and ligamentous instability.

Adult↗
PubMed1989

Ipsilateral supracondylar fracture of humerus and forearm bones in children.

A total of 34 children with ipsilateral supracondylar fractures of the humerus and forearm were studied over an 8-year period. Of these, 19 patients had fractures of the distal quarter of the forearm bones while eight patients had a distal radial epiphyseal injury. Five of the patients had undisplaced supracondylar fractures. One patient had an anterior supracondylar fracture. All forearm fractures were treated by closed reduction. Nine displaced supracondylar fractures which could not be reduced by closed manipulation were treated by olecranon pin traction in two cases and by percutaneous pinning in seven cases. Excellent or good results were found in 29 children after an average follow-up of 3.8 years.

Adolescent↗
PubMed1989

Quantitative structure-activity relationship study on some dihydropteridine reductase inhibitors.

The dihydropteridine reductase (DHPR) inhibitory potencies of some 4-phenyltetrahydropyridines, 4-phenylpiperidines, and 4-phenylpyridines, are analyzed in relation to their physico-chemical and molecular properties. They are found to have significant correlation with Hammett constant sigma and the van der Waals volume Vw. The correlation is linear with sigma and parabolic with Vw. Hence, it is argued that DHPR inhibition involves dispersion interaction and is enhanced by electron donation from the substituents but hindered by steric effects produced by large substituents. It is also found that these electronic and steric effects are significant only when they are produced by substituents being at specific position in the molecules.

Dihydropteridine Reductase↗
PubMed1989

A quantitative structure-activity relationship study on some pyrazolo[4,5-c]quinolines acting as inhibitors of benzodiazepine-receptor binding.

By a quantitative structure-activity relationship (QSAR) study, the ability of a series of 1-arylpyrazolo[4,5-c]quinolin-4-ones to displace specific [3H]-flunitrazepam from bovine brain membranes is shown to be significantly correlated with steric and hydrophobic constants of aryl subtituents, suggesting that substituents of 2- and 6-positions produce dominant steric effects and that those of 3- and 5-positions are involved in strong hydrophobic interaction with the receptor.

Animals↗
PubMed1989

A QSAR study on renin inhibitors.

Quantitative structure-activity relationships (QSAR) were studied in a series of chain-modified peptide analogues of the active site of angiotensinogen. The activity of these renin inhibitors was found to be significantly correlated with Kier's first-order valence molecular connectivity index (1 chi v) and with the molecular weight (MW) of the molecules. The activity was less well correlated with the van der Waals volume (Vw), and not at all with the hydrophobic character (log P) of the molecules. These findings suggest that there is a strong dispersion interaction between the inhibitor molecules and the enzyme, and that hydrophobicity plays little part in the interaction.

Amino Acid Sequence↗
PubMed1988

A quantitative structure-activity relationship study of 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase inhibitors.

A quantitative structure-activity relationship study has been made of some 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors. The HMG-CoA reductase inhibition activities of mevinolin analogs and 6-substituted 4-hydroxypyran-2 ones have been mostly found to be significantly correlated with the molecular size of substituents. In one case, however, the inhibition potency was found to be related to the hydrophobicity of molecules. These findings led us to suggest that the enzyme HMG-CoA reductase possesses an active site which is involved in dispersion interaction and another site which is involved in hydrophobic interaction with inhibitor molecules, depending upon the proper orientation of the latter towards these sites. Furthermore, the results indicate that both active sites possess limited steric bulk tolerance.

Chemical Phenomena↗
PubMed1988

A structure-activity relationship study on papaverine analogs.

The structure-activity relationship of papaverine analogs, the inhibitors of adenosine cyclic 3', 5'-monophosphate (c-AMP) phosphodiesterase, is discussed. The enzyme inhibition activity of these compounds are found to be dominantly controlled by hydrophobicity and steric factors. A significant quantitative correlation has been obtained between the inhibition activity and the van der Waals volume.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1987

A comprehensive study on the mechanism of inhibition of serine proteases by benzamidines based on quantitative structure-activity relationship studies.

Based on quantitative structure-activity relationship studies, investigation is made on the mechanism of inhibition of serine proteases, i.e., thrombin, plasmin, trypsin, and complement, by benzamidines. It is found that inhibitions of all the four enzymes, thrombin, plasmin, trypsin and complement, involve hydrophobic interaction in general but they do not involve electronic interaction in all the cases. In the cases where the electronic interaction is involved the mode of interaction is not necessarily the same. The electronic interaction depends upon the kind and the source of the enzyme.

Amidines↗