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Biomedical subjects

A K Saxena

Publications and source records attributed to A K Saxena.

At least 19 recordsLinked to original sources
PubMed2006

Tunneled catheters' outcome optimization among diabetics on dialysis through antibiotic-lock placement.

Efficacy and safety of antibiotic 'locks', in prevention of thrombotic and infectious complication-related morbidity and mortality, among diabetics dialyzed through tunneled-cuffed catheters (TCCs) has not been effectively investigated. This trial was designed to investigate the outcome of TCCs (n = 109), inserted among 96 diabetic end-stage renal disease patients (March 2002-February 2003), by comparing the catheter thrombosis, catheter-related bloodstream infections (CRBSI), catheter survival, and mortality rates, between the cohorts of 49 patients who had TCCs (n = 51) 'locked' with cefotaxime/heparin (group I) and 47 patients with TCCs (n = 58) filled with standard heparin (group II). Thrombosis was defined as the inability to use catheter at a blood flow of 200 ml/min despite intraluminal thrombolysis. Primary end points were catheter thrombosis and CRBSI; elective catheter removal and CRBSI-related death led to sensor of TCCs follow-up. Patients with intraluminal cefotaxime/heparin lock, on cumulative survival analysis, showed a superior thrombosis-free (86.3 vs 63.8%, P = 0.023, log rank), infection-free (72.9 vs 27.1%, P = 0.004, log rank), and thrombosis- and infection-free TCC survival (78.4 vs 37.9%, P = 0.001, log rank) at 365 days, besides having significantly lower incidence of CRBSI (1.56 vs 3.68 episodes/1000 catheter days, P < 0.0001) and CRBSI-related mortality (9.8 vs 23.4%, P = 0.015), compared with the heparin-alone group. Deployment of cefotaxime-heparin 'lock' enhances catheter survival; reduces thrombotic and infectious complications and ensuing mortality, among diabetics on dialysis. However, further studies are needed to define the long-term implications of antibiotic locks in terms of the risk of emergence of antimicrobial resistance.

Adult↗
PubMed2006

Synthesis and biological activity of amide derivatives of nimbolide.

Nimbolide (1), a limonoid isolated from Azadirachta indica, is the chief cytotoxic principle in Neem leaves extract. Using nimbolide as a lead compound for anti-cancer analogue design, a series of nimbolide derivatives have been synthesized and evaluated for in vitro cytotoxic activity against a panel of human cancer cell lines. Out of 10 compounds screened 2g, 2h and 2i showed potent activity.

Amides↗
PubMed2006

Development of alternative support system for viable count of cyanobacteria by most probable number method.

A technique was developed to evaluate alternative support systems to test tubes used in the standard most probable number technique, for simultaneous isolation and enumeration of cyanobacteria. Five different support systems were tested for their suitability in terms of accuracy, sensitivity, economics and ease of handling. PCR plates with 96 wells and carrying capacity of 300 microL per well were found to be most sensitive, besides being cost- and time-effective. This technique can also be useful for isolation of cyanobacteria, due to immobilization of colonies in the gel matrix and storage of samples at room temperature, without loss of viability for 5-6 weeks. This technique can help to process large sample size with ease--both for enumeration and isolation and can be extended for enumeration of other microorganisms from diverse sources.

Colony Count, Microbial↗
PubMed2006

Collection and preparation of molecular databases for virtual screening.

Drug discovery and development research is undergoing a paradigm shift from a linear and sequential nature of the various steps involved in the drug discovery process of the past to the more parallel approach of the present, due to a lack of sufficient correlation between activities estimated by in vitro and in vivo assays. This is attributed to the non-drug-likeness of the lead molecules, which has often been detected at advanced drug development stages. Thus a striking aspect of this paradigm shift has been early/parallel in silico prioritization of drug-like molecular databases (also database pre-processing), in addition to prioritizing compounds with high affinity and selectivity for a protein target. In view of this, a drug-like database useful for virtual screening has been created by prioritizing molecules from 36 catalog suppliers, using our recently derived binary QSAR based drug-likeness model as a filter. The performance of this model was assessed by a comparative evaluation with respect to commonly used filters implemented by the ZINC database. Since the model was derived considering all the limitations that have plagued the existing rules and models, it performs better than the existing filters and thus the molecules prioritized by this filter represent a better subset of drug-like compounds. The application of this model on exhaustive subsets of 4,972,123 molecules, many of which have passed the ZINC database filters for drug-likeness, led to a further prioritization of 2,920,551 drug-like molecules. This database may have a great potential for in silico virtual screening for discovering molecules, which may survive the later stages of the drug development research.

Computational Biology↗
PubMed2006

Omental plugging for large-sized duodenal peptic perforations: A prospective randomized study of 100 patients.

BACKGROUND: Due to friable margins and the moribund state of the patient, managing giant duodenal perforations (>20 mm in diameter) is a challenging task. METHODS: A prospective randomized study of 100 patients with large-sized (> 20 mm) duodenal peptic perforation comparing omental plugging (study group) with omentopexy (control group) was carried out. RESULTS: Size of the perforation varied between 20 to 30 mm. No study group patients developed a postoperative perforation site leak, as compared with 6 patients in the control group. Gastric outlet obstruction was significantly less at 6 weeks and 5 years in the study group as compared with the control group, and mortality was significantly less in the study group. CONCLUSION: It was concluded that omental plugging was a safe and reliable method of treatment for large-sized duodenal peptic perforations.

Adolescent↗
PubMed2006

Development of pharmacophoric model of condensed pyridine and pyrimidine analogs as hydroxymethyl glutaryl coenzyme A reductase inhibitors.

Quantitative structure-activity relationship (QSAR) has been established on a series of thirty-eight compounds of four different sets of condensed pyridine and pyrimidine analogs, for their hydroxymethyl glutaryl coenzyme (HMG-CoA) reductase inhibitor activity, in order to understand the essential structural requirement for binding with receptor, in terms of common biophoric and secondary sites employing APEX-3D software. Among several 3D pharmacophoric models with different sizes and arrangements, one model was selected based on r2 = 0.8, chance<0.001, match equivalent to 0.38 and all the 38 compounds were considered. The results suggest that hydrophobicity, hydrogen acceptor and optimum steric refractivity play a dominant role in the inhibition of HMG-CoA reductase. The information obtained from the present study can be used to design and predict more potent molecules as HMG-CoA reductase inhibitors, prior to their synthesis.

Drug Design↗
PubMed2005

A tuber lectin from Arisaema helleborifolium Schott with anti-insect activity against melon fruit fly, Bactrocera cucurbitae (Coquillett) and anti-cancer effect on human cancer cell lines.

An anti-insect and anti-cancer lectin has been isolated from Arisaema helleborifolium Schott by affinity chromatography using asialofetuin-linked amino activated silica beads. The bound A. helleborifolium lectin (AHL) was eluted with 100mM glycine-HCl buffer, pH 2.5. It gave a single band on SDS-PAGE, pH 8.3, and PAGE, pH 4.5. However, multiple bands were obtained in PAGE at pH 8.3 and isoelectric focusing. The lectin was a homotetramer having subunit molecular mass 13.4kDa while its native molecular mass was 52kDa. It was a glycoprotein with 3.40% carbohydrate and was stable up to 60 degrees C for 30min. It showed anti-insect activity towards second instar larvae of Bactrocera cucurbitae (Coquillett) with LC(50) value of 16.4microg/ml. Larvae fed on artificial diet containing sub-lethal dose of AHL showed a significant decrease in acid phosphatase and alkaline phosphatase activity while esterase activity markedly increased as compared to larvae fed on diet without lectin. AHL was also found to inhibit in vitro proliferation of some well established human cancer cell lines viz HOP-62 (95%), HCT-15 (92%), HEP-2 (66%), HT-29 (68%), PC-3 (39.4%), and A-549 (20.7%).

Acid Phosphatase↗
PubMed2005

Synthesis and biological evaluation of chalcones and their derived pyrazoles as potential cytotoxic agents.

A series of substituted chalcones and their corresponding pyrazoles were synthesized and evaluated for in vitro cytotoxic activity against a panel of human cancer cell lines. Out of 93 compounds screened, 8 compounds, 1s, 3i,j,n, 4i,j,n and 4s, showed marked activity. Compounds 4j,n and 4s were found to be the most promising in this study. SAR is also discussed.

Antineoplastic Agents↗
PubMed2005

Mitogenic and anti-proliferative activity of a lectin from the tubers of Voodoo lily (Sauromatum venosum).

A new lectin with the potent mitogenic and in vitro anti-proliferative activity was isolated from the tubers of a wild monocotyledonous plant Sauromatum venosum (Schott), from the family Araceae, by affinity chromatography on the asialofetuin linked amino-activated silica beads. The apparent native molecular mass of S. venosum lectin (SVL), as determined by gel filtration chromatography, was 54 kDa. In HPLC, size exclusion and cation exchange chromatography, SVL gave a single peak and also a single band of 13.5 kDa in SDS-PAGE, pH 8.3, under reducing and non-reducing conditions, indicating that the lectin is composed of four identical subunits. S. venosum lectin agglutinated rabbit, rat, sheep and guinea pig erythrocytes but reacted with goat erythrocytes after the neuraminidase treatment. However, SVL was unable to agglutinate human ABO blood group erythrocytes even after treatment with neuraminidase. SVL was inhibited by N-acetyl-D-Lactosamine (LacNAc), which is an important marker in various carcinomas and a complex desialylated glycoprotein, asialofetuin. The amino acid composition showed that lectin contained a high amount of aspartic acid and glycine but totally devoid of cysteine. However, trace amounts of methionine was present. The lectin showed a potent mitogenic response towards BALB/c splenocytes and human lymphocytes. As the mitogenic stimulation was more than that of Con A, a standard well-known plant mitogen and the response of this lectin was almost double than that of Con A. This lectin is endowed with proliferation of T cells as revealed by IL-2 bioassay but showed no production of immunoglobulins thus indicating the non-stimulation of B cells. SVL significantly inhibited the proliferation of murine cancer cell-lines, i.e., WEHI-279 to 84.6%, J774 to 81%, P388D1 to 74% and A-20 to 47%. In addition, the in vitro anti-proliferative activity of SVL was also evaluated against nine human cancer cell lines representing different organs and tissues namely, T-47D (breast), SiHa (cervix), SK-N-MC (CNS), SK-N-SH (CNS), SW-620 (colon), HT-29 (colon), HEP-2 (liver), OVCAR-5 (ovary) and PC-3 (prostate). SVL showed a significant inhibition towards the entire cell lines except the cell lines from CNS, which showed partial response in comparison to a standard anticancer drug adriamycin which was used at a concentration of 5 x 10(-5) M. Thus the anti-proliferative ability of SVL may be helpful in identification of new lectin probes that can lead to better understanding in the detection and study of certain types of cancer.

Animals↗
PubMed2005

Isolation of a novel N-acetyl-D-lactosamine specific lectin from Alocasia cucullata (Schott.).

An N-acetyl-D: -lactosamine (LacNAc) specific lectin from tubers of Alocasia cucullata was purified by affinity chromatography on asialofetuin-linked amino activated silica. The pure lectin showed a single band in SDS-PAGE at pH 8.8 and was a homotetramer with a subunit molecular mass of 13.5 kDa and native molecular mass of 53 kDa. It was heat stable up to 55 degrees C for 15 min and showed optimum hemagglutination activity from pH 2 to 11. The lectin was affected by denaturing agents such as urea (2 M: ), thiourea (2 M: ) and guanidine-HCl (0.5 M: ) and did not require Ca2+ and Mn2+ for its activity. It was a potent mitogen at 10 microg/ml towards human peripheral blood mononuclear cells with 50% growth inhibitory potential towards SiHa (human cervix ) cancer cell line at 100 microg/ml.

Alocasia↗
PubMed2005

Role of duplex Doppler and power Doppler sonography in transplanted kidneys with acute renal parenchymal dysfunction.

The limited work published on the comparison of power Doppler sonography (PDS) and duplex Doppler sonography (DDS) in the assessment of acute renal allograft dysfunction has shown contradictory results. We compared the role of DDS and PDS in renal transplant recipients developing acute renal parenchymal dysfunction and correlated these findings with kidney biopsy, which was taken as the gold standard. Thirty post-renal transplant patients with acute graft dysfunction underwent Doppler sonography, DDS and PDS using an HDI 5000 ATL machine. Patients who developed graft dysfunction as a result of vascular, obstructive or other non-parenchymal causes were excluded. All patients underwent an allograft biopsy within 72 h of the sonography. Based on the biopsy findings, 24 patients were categorized as having acute rejection, and six patients as having no rejection. The overall sensitivity, specificity and accuracy of DDS for evaluation of graft dysfunction were 54.17, 33.33, and 50.00%, respectively, and that for PDS were superior with 87.50, 33.30, and 76.67%, respectively. The low specificity can be partially attributed to the small number of cases without rejection in our study population. We conclude that PDS is superior to DDS in screening patients with acute parenchymal renal dysfunction post-transplant. However, a normal PDS examination does not exclude the presence of acute rejection. Power Doppler sonography is a useful screening test for diagnosing acute rejection but a renal allograft biopsy remains the gold standard for diagnosis of this condition.

Adolescent↗