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Biomedical subjects

A K Saxena

Publications and source records attributed to A K Saxena.

At least 37 records · Page 2Linked to original sources
PubMed2004

Multilocular cystic renal cell carcinoma in a child.

Multilocular cystic renal cell carcinoma is an extremely rare condition in adults with no previous case reports in the pediatric age group. The authors report on an 8-year-old girl who underwent nephrectomy for a right-sided renal cystic disease because of extensive involvement of the kidney. Subsequent histopathologic examination findings showed presence of renal cell carcinoma in all the cysts. Awareness of this malignancy in a child is extremely important in the background of recent reports advocating conservative wait and watch management in unilateral renal cystic disease, which has similar clinical and imaging findings.

Carcinoma, Renal Cell↗
PubMed2004

Duplication cyst of the stomach presenting as hemoptysis.

We report a rare case of a 2-year-old boy with a gastric duplication cyst located in the stomach, presenting with vague abdominal pain, recurrent cough, hemoptysis and a lesion in the left lower lobe of the lung reported as a sequestration. The duplication cyst was attached to the diaphragm and lungs by a narrow tract. The cyst was excised. Subsequent scans of the chest showed regression of the lung lesion. We believe this to be the first case in the literature where the hemoptysis was cured and the pulmonary lesion regressed completely after excision of the duplication cyst of the stomach alone. Pulmonary resection was thus avoided.

Child, Preschool↗
PubMed2004

Rectal atresia, choanal atresia and congenital heart disease: a rare association.

Rectal atresia is an extremely rare anorectal malformation. A unique case of rectal atresia presenting as an imperforate membrane associated with congenital cardiac malformations and unilateral choanal atresia in a newborn is reported. Ultrasound examination in the newborn infant located the presence of the rectal membrane which was surgically treated successfully.

Choanal Atresia↗
PubMed2003

Assay method for quality control and stability studies of a new CVS disorder agent (compound 93/478).

1-[4-(4-fluorophenyl)-piperazine-1-yl]-3-(2-oxopyrrolidin-1-yl)-propane hydrochloride, (I), (CDRI code No. 93/478) is a new potent anti-ischemic and anti-hypertensive agent, being developed at the Central Drug Research Institute (CDRI), Lucknow, India. A sensitive high performance liquid chromatographic assay method has been developed and validated for in process quality control and for stability studies. HPLC separation was achieved on a C(18) Purospher (Merck) column using a gradient of 0.02% tetra-methyl ammonium hydroxide (pH 7.5) and acetonitrile as mobile phase. The eluents were monitored by diode array detector at 240 and 290 nm. The lower limit of detection of I was 0.62 microg/ml, while the lower limit of quantitation was set to be 1.5 microg/ml. The calibration curves were linear in the range 1.5-62 microg/ml. Reproducibility of the method was determined by inter and intra assay variation, which were <10%.

Calibration↗
PubMed2003

In vitro cytotoxic elemanolides from Vernonia lasiopus.

Two new elemanolides, epivernodalol and lasiopulide, were isolated after chromatographic separation of the alcoholic extract of the dried aerial parts of the Vernonia lasiopus. These elemanolides are new C-10 epimers of the sesquiterpene lactones vernodalol and demethylacroylated vernodalol isolated from other species of Vernonia. Both elemanolides showed in vitro cytotoxicity against human cancer cell lines in culture. This is the first report of isolation and cytotoxic activity of the two elemanolides from V. lasiopus.

Antineoplastic Agents, Phytogenic↗
PubMed2003

Evaluation of naphthalmustine, a nitrogen mustard derivative of naphthalimide as a rationally-designed anticancer agent.

Naphthalmustine, 2-[2-[bis-(2-chloroethyl)amino]ethyl]-1H-benz[de]isoquinoline-1,3-dione (Compound 1) has been synthesized as a rationally designed new anticancer agent from N-(2-bromoethyl)naphthalimide. Its chemical alkylating activity exceeded that of nor-HN2 used as standard compound for comparison. Its antitumour efficacy was assessed in vivo in two murine ascites tumours namely Sarcoma-180 (S-180) and Ehrlich ascites carcinoma (EAC) by measuring the increase in median survival times (MST) of drug treated (T) over untreated control (C) mice. The clinical drug cyclophosphamide and the experimental compound mitonafide were used as positive controls for comparison. Compound 1 has displayed substantial and reproducible antitumoural activity in these tumours since very high remission times of treated animals were observed. Significant increase in the life span of mice bearing highly advanced tumour for 10 days before the drug challenge was also noted after its treatment. Its LD50 value was 200 mg/Kg by single i.p. injection. Its toxicity was also assessed in vivo in normal and in S-180 bearing mice by measuring drug-induced changes in hematological parameters, femoral bone marrow and splenic cellularity sequentially on days 9, 15 and 21 following drug treatment at the optimum dose of 12 mg/kg from day 1 to 7. The results indicated that the compound did not adversely affect hematopoiesis. Drug-induced hepatotoxicity and nephrotoxicity were also evaluated on those days but no such toxicities were detected. Naphthalmustine inhibits the synthesis of DNA and RNA in S-180 tumour cells. It was further screened in vitro in 4 different human tumour cell lines but no significant activity was observed in those lines.

Animals↗
PubMed2001

Hepatoprotective activity of indigtone--a bioactive fraction from Indigofera tinctoria Linn.

A bioactive fraction, indigtone (FA), obtained by fractionation of a petroleum ether extract of the aerial parts of Indigofera tinctoria, showed significant dose related hepatoprotective activity against CCl(4) induced liver injury in rats and mice. Hexobarbitone induced 'sleeptime', zoxazolamine induced 'paralysis time', levels of transaminases, bilirubin and total protein in serum were employed as indices of liver injury. Pre and post treatment with FA significantly reversed the majority of the parameters altered by the hepatotoxin. This indicated the preventive and restorative effect of FA in the process of CCl(4) induced liver damage. The fraction possessed a high therapeutic ratio, as no mortality was observed up to a dose of 2 g/kg p.o. in mice.

Animals↗
PubMed2001

Adaptogenic activity of a novel, withanolide-free aqueous fraction from the roots of Withania somnifera Dun.

The practitioners of the traditional Indian system of medicine regard Withania somnifera Dun. as the 'Indian ginseng'. A new withanolide-free aqueous fraction was isolated from the roots of this plant and was evaluated for putative antistress activity against a battery of tests such as hypoxia time, antifatigue effect, swimming performance time, swimming induced gastric ulceration and hypothermia, immobilization induced gastric ulceration, autoanalgesia and biochemical changes in the adrenal glands. This bioactive fraction exhibited significant antistress activity in a dose-related manner in all the parameters studied. The extract of Withania somnifera root (a commercial preparation available locally) was used to compare the results. A preliminary acute toxicity study in mice showed a good margin of safety.

Animals↗
PubMed2001

Selection and evaluation of Azospirillum brasilense strains growing at a sub-optimum temperature in rhizocoenosis with wheat.

Fourteen Azospirillum brasilense strains growing at a sub-optimum temperature were selected based on their ability to grow and carry out plant growth promoting activities at 22 degrees C. The strains were tested for their response to inoculation in wheat (two popular cultivars, HD2285 and WH547, under sterile conditions) crop using sterile and nonsterile rooting medium. Significant increase in plant growth parameters was observed; the overall response to inoculation was better in cultivar HD2285. Based on their performance under sterile conditions, 4 strains were selected and compared under nonsterile conditions with strain sensitive to a sub-optimum temperature in pots using wheat variety HD2285. The strains capable of growing at the sub-optimum temperature can colonize the wheat endorhizosphere efficiently and improve the plant growth and yield as compared to sensitive strain; a 25-27% increase in grain yield was found on inoculating two selected strains compared to NO3- control.

Azospirillum brasilense↗
PubMed2001

3-D QSAR studies of triazolinone based balanced AT1/AT2 receptor antagonists.

Essential structural and physicochemical requirements in terms of common biophoric sites (pharmacophore) and secondary sites for binding and interacting with AT1 and AT2 receptors have been identified using APEX-3-D expert system on 16 N2- aryl triazolinone biphenyl sulphonamides. Among several biophoric 3-D QSAR models two models (Nos. 1 and 2) having R2 > 0.7, chance <0.05 and match >0.5 and two models (Nos. 3 and 4) having R2 > 0.89, chance <0.03 and match >0.5 with three biophoric sites and two secondary sites (except model No. 4 with three secondary sites) describe the variation in AT1 and AT2 antagonistic activities, respectively.

Angiotensin I↗
PubMed2001

Synthesis, molecular modeling and QSAR studies in chiral 2,3-disubstituted-1,2,3,4-tetrahydro-9H-pyrido(3,4-b)indoles as potential modulators of opioid antinociception.

In view of coexistence of opioid and cholecystokinin (CCK) in the brain areas concerned with pain processing, some semirigid racemic and chiral analogues of a potent CCK receptor antagonist (benzotript) have been synthesized and tested for their modulatory role on opioid antinociception, which may be mediated by CCK-B receptor. Some of these compounds, 3e, 3g, 3h, 4a, 4b and 4h, exhibited antinociceptive potentiation comparable to benzotript and proglumide. In order to identify the essential chemical structural features important for this potentiation, molecular modeling and quantitative structure activity relationship (QSAR) studies have been carried out in the S and R enantiomers of some of these semi-rigid compounds. The 3D-biophore models, common to all molecules of the training set have been derived. These models with superimposition (match value >0.25) depicted three biophoric sites one each for, pi/hydrophobic interactions, hydrogen bonding and ionic interactions among the phenyl/pyrrole ring, indole nitrogen, amidic oxygen, pyridyl nitrogen and lone pair of amidic oxygen. The total hydrophobicity and S absolute stereochemistry are found to positively contribute to potentiation of antinociception induced by morphine and the resulting quantitative pharmacophoric model with good correlation is found to well describe the observed activity.

Analgesics, Non-Narcotic↗
PubMed2001

Synthesis and QSAR studies in 2-(N-aryl-N-aroyl)amino-4,5-dihydrothiazole derivatives as potential antithrombotic agents.

A series of 2-(N-aryl-N-aroyl)amino-4,5-dihydrothiazole derivatives have been synthesized via cyclocondensation of N-aryl thioureas with 2-bromoethylamine hydrobromide followed by the reaction of the product thus obtained with aroyl chlorides. Title compounds were evaluated for their antithrombotic activity in vivo in mice where one of these compound 29 provided 65% protection as compared to 77% protection offered by the standard Indomethacin. Quantitative Structure-Activity Relationship (QSAR) studies were performed on these compounds using physicochemical (hydrophobic, electronic, steric) parameter as independent and antithrombic activity as dependent parameter, where antithrombotic activity correlated best (r > 0.8) with electronic parameters (F, sigma or mu) having high statistical significance > 99.9% (F(2,22)>15.0; F(2,22alpha:0.001)=11.0) suggesting that hydrophobic, steric and resonance factors are insignificant in this set of molecules for the activity.

Animals↗
PubMed2001

Synthesis and QSAR studies of 4-substituted phenyl-2,6-dimethyl-3, 5-bis-N-(substituted phenyl)carbamoyl-1,4-dihydropyridines as potential antitubercular agents.

Synthesis and QSAR studies of the title compounds have resulted in the identification of structural and physicochemical parameters (MR, sigma(o), sigma(m), sigma(p)) contributing to antitubercular activity. Among these, carbamoyl phenyl ring substituted at 3 and 4 position with NO(2) group or 2 position with Cl or OCH(3) group shows >90% inhibition against H(37)Rnu comparable to other substituted phenyls.

Antitubercular Agents↗
PubMed2001

Suppression of maize root diseases caused by Macrophomina phaseolina, Fusarium moniliforme and Fusarium graminearum by plant growth promoting rhizobacteria.

A plant growth-promoting isolate of a fluorescent Pseudomonas sp. EM85 and two bacilli isolates MR-11(2) and MRF, isolated from maize rhizosphere, were found strongly antagonistic to Fusarium moniliforme, Fusarium graminearum and Macrophomina phaseolina, causal agents of foot rots and wilting, collar rots/stalk rots and root rots and wilting, and charcoal rots of maize, respectively. Pseudomonas sp. EM85 produced antifungal antibiotics (Afa+), siderophore (Sid+), HCN (HCN+) and fluorescent pigments (Flu+) besides exhibiting plant growth promoting traits like nitrogen fixation, phosphate solubilization, and production of organic acids and IAA. While MR-11(2) produced siderophore (Sid+), antibiotics (Afa+) and antifungal volatiles (Afv+), MRF exhibited the production of antifungal antibiotics (Afa+) and siderophores (Sid+). Bacillus spp. MRF was also found to produce organic acids and IAA, solubilized tri-calcium phosphate and fixed nitrogen from the atmosphere. All three isolates suppressed the diseases caused by Fusarium moniliforme, Fusarium graminearum and Macrophomina phaseolina in vitro. A Tn5:: lacZ induced isogenic mutant of the fluorescent Pseudomonas EM85, M23, along with the two bacilli were evaluated for in situ disease suppression of maize. Results indicated that combined application of the two bacilli significantly (P = 0.05) reduced the Macrophomina-induced charcoal rots of maize by 56.04%. Treatments with the MRF isolate of Bacillus spp. and Tn5:: lacZ mutant (M23) of fluorescent Pseudomonas sp. EM85 significantly reduced collar rots, root and foot rots, and wilting of maize caused by Fusarium moniliforme and F. graminearum (P = 0.05) compared to all other treatments. All these isolates were found very efficient in colonizing the rhizotic zones of maize after inoculation. Evaluation of the population dynamics of the fluorescent Pseudomonas sp. EM85 using the Tn5:: lacZ marker and of the Bacillus spp. MRF and MR-11(2) using an antibiotic resistance marker revealed that all the three isolates could proliferate successfully in the rhizosphere, rhizoplane and endorhizosphere of maize, both at 30 and 60 days after seeding. Four antifungal compounds from fluorescent Pseudomonas sp. EM85, one from Bacillus sp. MR-11(2) and three from Bacillus sp. MRF were isolated, purified and tested in vitro and in thin layer chromatography bioassays. All these compounds inhibited R. solani, M. phaseolina, F. moniliforme, F. graminearum and F. solani strongly. Results indicated that antifungal antibiotics and/or fluorescent pigment of fluorescent Pseudomonas sp. EM85, and antifungal antibiotics of the bacilli along with the successful colonization of all the isolates might be involved in the biological suppression of the maize root diseases.

Antibiosis↗
PubMed2001

Molecular modeling and 3D-QSAR studies in 2-aziridinyl-and 2,3-bis(aziridinyl)-1,4-naphthoquinonyl sulfonate and acylate derivatives as potential antimalarial agents.

Malaria is still continuing to be one of the most dreadful diseases of the tropical countries particularly due to the development of resistance to the existing antimalarials. From observed, antimalarial activity of 2-aziridinyl- and 2,3-bis(aziridinyl)-1,4-naphthoquinonyl sulfonate and acylate derivatives acting through redox cycling mechanism, molecular modeling and three dimensional-quantitative structure activity relationship (3D-QSAR) studies have been carried out on a set of 63 compounds to identify important pharmacophors. Among several 3D-QSAR models generated, three models with correlation coefficient r > 0.82, match > 0.60 and chance = 0.00 have shown two common biophoric sites: one being the oxygen atom at position 1 of the naphthoquinone ring in terms of pi-population, charge and electron donating ability while the second being the center of the phenyl ring in terms of its 6pi-electrons. In addition to these sites, the models also share two common secondary sites: one positively contributing H-acceptor site while the second site contributing negatively in terms of steric refractivity. All these models showed good agreement between the experimental, calculated and predicted antimalarial activities.

Antimalarials↗