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Biomedical subjects

S Mandal

Publications and source records attributed to S Mandal.

At least 19 recordsLinked to original sources
PubMed2002

Toxin-producing plankton may act as a biological control for planktonic blooms--field study and mathematical modelling.

Termination of planktonic blooms is of great importance to human health, ecosystem, environment, tourism and fisheries. Toxic substances released by plankton play an important role in this context. The effect of toxin-producing plankton (TPP) on zooplankton is observed from the field-collected samples and mathematical modelling. Information from both the studies led us to suggest that TPP may terminate the planktonic blooms by decreasing the grazing pressure of zooplankton and thus acts as a biological control.

Animals↗
PubMed2002

Bilateral cryptorchidism with bilateral inguinal hernia and retrovesical mass in an infertile man: single-stage laparoscopic management.

A 30-year-old married man presented with the complaint of inability to procreate. Examination revealed bilateral nonpalpable testes and bilateral inguinal hernia. Ultrasonography of the abdomen could not locate the testis; instead, a hypoechoic 5 x 5-cm mass was found behind the bladder. A CT scan of the abdomen revealed the right testis near the right inguinal canal. The left testis could not be identified beside the soft tissue mass. The patient was taken for diagnostic as well as therapeutic laparoscopy. The testis on the right was found just proximal to the internal inguinal ring, and right orchidopexy was done. The left testis was small and rudimentary; hence, orchidectomy was done. Bilateral laparoscopic herniorrhaphy was carried out with polypropylene mesh by fixing it intracorporeally to the pubic bone, Cooper's ligament, inguinal ligament, and conjoint tendon. Subsequently, the retrovesical mass was excised and retrieved by dilating the umbilical port site. The operative time was 3.5 hours with minimal blood loss. The postoperative period was uneventful, and the patient was discharged after 24 hours. The histopathology examination of the retrovesical mass showed an extragonadal germ cell tumor compatible with seminoma.

Adult↗
PubMed2001

Dielectric relaxation in a single tryptophan protein.

Although dielectric relaxation can significantly affect the intrinsic fluorescence properties of a protein, usually it is fast compared to fluorescence timescales and needs to be slowed down by adding viscogens or lowering temperature before its impact on fluorescence can be studied. We report here a remarkable blue shift in fluorescence upon bimolecular quenching in the single-tryptophan thermostable protein Bj2S, the 2S seed albumin from Brassica juncea, at ambient temperature and viscosity. The magnitude of the blue shift ( approximately 5 nm at 50% quenching by acrylamide) is striking in a single-tryptophan protein and is attributed to a slowly relaxing dielectric environment in Bj2S from red edge excitation, steady-state polarization and time-resolved fluorescence experiments. Our results have important implications on interpretation of fluorescence of proteins with highly constrained backbones and in designing model systems for studying slow protein solvation dynamics using Trp fluorescence as the reporter probe.

Albumins↗
PubMed2001

Diffusion with rearranging traps.

A model for diffusion on a cubic lattice with a random distribution of traps is developed. The traps are redistributed at certain time intervals. Such models are useful for describing systems showing dynamic disorder, such as ion-conducting polymers. In the present model the traps are infinite, unlike an earlier version with finite traps. For the infinite trap version a simple analytical calculation is possible and the results agree qualitatively with simulations.

Journal Article↗
PubMed2000

Novel tert-butyl migration in copper-mediated phenol ortho-oxygenation implicates a mechanism involving conversion of a 6-hydroperoxy-2,4-cyclohexadienone directly to an o-quinone

Copper mediated ortho-oxygenation of phenolates may proceed through the generation of a 6-peroxy-2,4-cyclohexadienone intermediate. To test this theory, we studied the fate of sodium 4-carbethoxy-2, 6-di-tert-butylphenolate, where the ortho-oxygenation sites are blocked by tert-butyl groups. Using the Cu(I) complex of N, N-bis(2-(N-methylbenzimidazol-2-yl)ethyl)benzylamine, isolation of the major oxygenated product and characterization by single-crystal X-ray crystallography and NMR spectroscopy revealed it to be 4-carbethoxy-3,6-di-tert-butyl-1,2-benzoquinone, resulting from a 1, 2-migration of a tert-butyl group. The independently prepared 6-hydroperoxide is transformed by the Cu(I)- (or Cu(II)-) ligand complex to the same o-quinone. The observed 1,2-migration of the tert-butyl group appears to reflect an electron demand created by rearrangement of the postulated peroxy intermediate. A mechanism proceeding alternatively through a catechol and subsequent oxidation to the o-quinone seems ruled out by a control study demonstrating that the requisite intermediate to catechol formation would instead eliminate the 2-tert-butyl group.

Journal Article↗
PubMed2000

Marjolin's ulcer of the suprapubic cystostomy site infiltrating the urinary bladder: a rare occurrence.

We report a case of a 40-year-old man who had presented with a spontaneous suprapubic urinary leak from a well-healed suprapubic cystostomy tract scar, 20 years following a successful scrotal tube substitution urethroplasty done for a post-traumatic urethral stricture. Preoperative contrast studies suggested a recurrent bulbomembranous urethral stricture. Excision biopsy of the suprapubic fistulous tract revealed scar cancer infiltrating the bladder wall. Of 3 similar cases reported in the past, only 1 had bladder involvement. Ours is the second such case with bladder involvement.

Adult↗
PubMed2000

DNA-cleavage studies on N-substituted monocyclic enediynes: enhancement of potency by incorporation of intercalating or electron poor aromatic ring and subsequent design of a novel phototriggerable acyclic enediyne.

A number of novel N-substituted enediynes (azaenediynes) 1-4 were synthesized as DNA cleaving agents. Enhancement of DNA cleavage potency was observed with those compounds which could interact with DNA through intercalation of the extended aromatic ring or through electrostatic attraction with electron poor aromatic ring. An acyclic enediyne 5 with a novel phototriggerable device was also synthesized and its DNA-cleaving activity was established.

DNA↗
PubMed2000

Infundibulopelvic anatomy and clearance of inferior caliceal calculi with shock wave lithotripsy.

PURPOSE: We evaluate the significance of inferior caliceal radiographic anatomy and determine its influence on successful fragmentation and clearance of inferior caliceal calculi with extracorporeal shock wave lithotripsy (ESWL). MATERIALS AND METHODS: Between November 1996 and February 1998, 88 patients and 90 renal units with single or multiple inferior caliceal calculi of all sizes and composition were treated with ESWL. The size, number and area of calculi, length and width of the stone bearing inferior calix and infundibulopelvic angle were determined on pretreatment excretory urography. The infundibulopelvic angle was measured by 2 methods using the angle between the inferior caliceal infundibular and ureteral axes (angle 1), and between the infundibular and ureteropelvic axes (angle 2). Cases with residual fragments not clearing within 6 months of satisfactory fragmentation after lithotripsy were considered failures. RESULTS: Overall stone clearance at 6 months was achieved in about 72% of the renal units. Infundibular length was 30 mm. or less in 77% of successful cases and in 64% of failures. Similarly, the smallest infundibular width of 5 mm. or more was found in 75% of successful cases compared to 41% of failures. Angle 1 of 35 degrees or more was observed in 73% of cases with compared to 18% without clearance. Angle 2 of 45 degrees or more was seen in 71% of successful cases compared to 9% of failures. The chances of a patient becoming stone-free with all favorable criteria of infundibular length 30 mm. or less, infundibular width 5 mm. or greater and infundibular ureteropelvic angle 45 degrees or greater was 100% (23 patients). CONCLUSIONS: Radiographic features of a stone bearing inferior calix and its relation to the renal pelvis can be easily measured on standard excretory urography. An infundibular width of 5 mm. or more and infundibulopelvic angle 1 of 35 degrees or more or angle 2 of 45 degrees or more were statistically significant factors of radiographic anatomy in stone clearance following ESWL. Inferior caliceal length was not statistically significant, although length of 30 mm. or less appeared to be more favorable for stone clearance. The ideal treatment of inferior caliceal calculi in patients with all 3 favorable criteria is ESWL.

Adult↗
PubMed2000

Luteolin, an abundant dietary component is a potent anti-leishmanial agent that acts by inducing topoisomerase II-mediated kinetoplast DNA cleavage leading to apoptosis.

BACKGROUND: Plant-derived flavonoids, which occur abundantly in our daily dietary intake, possess antitumor, antibacterial, and free radical scavenging properties. They form active constituents of a number of herbal and traditional medicines. Several flavonoids have been shown to exert their action by interacting with DNA topoisomerases and promoting site-specific DNA cleavage. Therefore, flavonoids are potential candidates in drug design. We report here that, although the flavonoids luteolin and quercetin are potent antileishmanial agents, luteolin has great promise for acting as a lead compound in the chemotherapy of leishmaniasis, a major concern in developing countries. MATERIALS AND METHODS: Kinetoplast DNA (kDNA) minicircle cleavage in drug-treated parasites was measured by electrophoresis of the total cellular DNA, followed by Southern hybridization using 32P labeled kDNA as a probe. Cell cycle progression and apoptosis were measured by flow cytometry using propidium iodide and fluorescein isothiocyanate (FITC)-labeled Annexin V. RESULTS: Luteolin and quercetin inhibited the growth of Leishmania donovani promastigotes and amastigotes in vitro, inhibited DNA synthesis in promastigotes, and promoted topoisomerase-II-mediated linearization of kDNA minicircles. The IC50 values of luteolin and quercetin were 12.5 microM and 45.5 microM, respectively. These compounds arrest cell cycle progression in L. donovani promastigotes, leading to apoptosis. Luteolin has no effect on normal human T-cell blasts. Both luteolin and quercetin reduced splenic parasite burden in animal models. CONCLUSION: Luteolin and quercetin are effective antileishmanial agents. Quercetin has nonspecific effects on normal human T cells, but luteolin appears nontoxic. So, luteolin can be a strong candidate for antileishmanial drug design.

Animals↗
PubMed1999

Cleogynol, a novel dammarane triterpenoid from Cleome gynandra.

Chemical examination of Cleome gynandra (whole plant excluding seeds) led to the isolation and identification of a novel (20S, 24S)-epoxy-19,25-dihydroxydammarane-3-one hemiketal (1). The structure of the new compound, designated cleogynol, was determined using spectral and chemical methods.

Acetylation↗
PubMed1998

Immunogenetic analysis of Buerger's disease in India.

In order to understand the role of HLA linked factors in determining susceptibility to Buerger's disease, we have studied 21 unrelated Asian Indian patients belonging to the North Indian states of Punjab, Haryana, Uttar Pradesh and Delhi, representing mainly a lower socioeconomic background. The data was compared with healthy controls belonging to the same ethnic group. The study revealed an over representation of HLA-B40 (60+61) (chi2=6.12; P<0.02) and DR2 (chi2=10.2; P<0.002). Amongst the patients no particular association or linkage disequilibrium with any of the five alleles of the MIC-A gene could be derived in the small sample size studied.

Adult↗
PubMed1998

Theoretical analysis of cell separation based on cell surface marker density.

A theoretical analysis was performed to determine the number of fractions a multidisperse, immunomagnetically labeled cell population can be separated into based on the surface marker (antigen) density. A number of assumptions were made in this analysis: that there is a proportionality between the number of surface markers on the cell surface and the number of immunomagnetic labels bound; that this surface marker density is independent of the cell diameter; and that there is only the presence of magnetic and drag forces acting on the cell. Due to the normal distribution of cell diameters, a "randomizing" effect enters into the analysis, and an analogy between the "theoretical plate" analysis of distillation, adsorption, and chromatography can be made. Using the experimentally determined, normal distribution of cell diameters for human lymphocytes and a breast cancer cell line, and fluorescent activated cell screening data of specific surface marker distributions, examples of theoretical plate calculations were made and discussed.

Antigens, Surface↗
PubMed1998

Analysis of the free amino acid content in pollen of nine Asteraceae species of known allergenic activity.

The study reports the free amino acid composition of the pollen of nine members of the family Asteraceae, i.e. Ageratum conyzoides L., Blumea oxyodonta DC., Eupatorium odoratum L., Gnaphalium indicum L., Mikania scandens Willd., Parthenium hysterophorus L., Spilanthes acmella Murr., Vernonia cinerea (L.) Lees. and Xanthium strumarium L. by thin layer chromatography. The amino acid content was found to vary from 0.5-4.0% of the total dry weight. Fourteen amino acids were identified, among which amino-n-butyric acid, aspartic acid and proline were present in almost all pollen samples. The other major amino acids present in free form included arginine, cystine, glutamic acid, glycine, isoleucine, leucine, methionine, ornithine, tryptophan and tyrosine.

Amino Acids↗
PubMed1998

Protein profile of the allergenic pollen of Ipomoea fistulosa L.--a comparative study.

The pollen of Ipomoea fistulosa L. is an important aeroallergen of India. The pollen of this plant was collected from full bloomed flowers growing in different places of West Bengal, India. Protein content and profile were studied by SDS-PAGE. Skin-prick tests with pollen antigens of all the samples were also performed. Considerable variation in the protein content and profile was noted with the highest protein content in the collected sample of Calcutta showing highest number of protein bands (10) designated as IF1 to IF10 with their weights ranging between 31 kDa to 89 kDa and 3 bands (IF8, IF9 and IF10) having molecular weights less than 29 kDa. Skin-prick tests also revealed highest degree of sensitivity to the Calcutta sample giving positive response in 52% of the patients. Skin reactivity ranged between 1+ to 3+.

Allergens↗