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T Mukherjee

Publications and source records attributed to T Mukherjee.

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

Surface enhanced Raman scattering of benzotriazole: a molecular orientational study.

Surface enhanced Raman scattering of benzotriazole in aqueous silver sol at pH approximately 9 has been investigated. The spectra of the molecule at various concentrations were recorded and the maximum enhancement was observed with a 10(-5) M solution. From the comparison of the surface enhanced Raman spectra with the conventional Raman spectra and applying "surface selection rule", it is inferred that the molecular ion interacts with the silver sol via the nitrogen atoms of the benzotriazole ring and the molecule assumes a near "end-on" orientation.

Argon↗
PubMed2004

Camptothecin induced mitochondrial dysfunction leading to programmed cell death in unicellular hemoflagellate Leishmania donovani.

The parasites of the order kinetoplastidae including Leishmania spp. emerge from most ancient phylogenic branches of unicellular eukaryotic lineages. In their life cycle, topoisomerase I plays a significant role in carrying out vital cellular processes. Camptothecin (CPT), an inhibitor of DNA topoisomerase I, induces programmed cell death (PCD) both in the amastigotes and promastigotes form of L. donovani parasites. CPT-induced cellular dysfunction in L. donovani promastigotes is characterized by several cytoplasmic and nuclear features of apoptosis. CPT inhibits cellular respiration that results in mitochondrial hyperpolarization taking place by oligomycin-sensitive F0-F1 ATPase-like protein in leishmanial cells. During the early phase of activation, there is an increase in reactive oxygen species (ROS) inside cells, which causes subsequent elevation in the level of lipid peroxidation and decrease in reducing equivalents like GSH. Endogenous ROS formation and lipid peroxidation cause eventual loss of mitochondrial membrane potential. Furthermore, cytochrome c is released into the cytosol in a manner independent of involvement of CED3/CPP32 group of proteases and unlike mammalian cells it is insensitive to cyclosporin A. These events are followed by activation of both CED3/CPP32 and ICE group of proteases in PCD of Leishmania. Taken together, our study indicates that different biochemical events leading to apoptosis in leishmanial cells provide information that could be exploited to develop newer potential therapeutic targets.

Animals↗
PubMed2004

Electron transfer interaction of dihydroxyquinones with amine quenchers: dependence of the quenching kinetics on the aliphatic and aromatic nature of the amine donors.

Studies on the electron transfer (ET) interaction of 1,4-dihydroxy-9,10-anthraquinone and 6,11-dihydroxy-5,12-naphthacenequinone with aliphatic and aromatic amine (AlA and ArA, respectively) donors have been investigated in acetonitrile solutions. Steady-state (SS) measurements show quenching of the quinone fluorescence by amines, without indicating any change in the shape of the fluorescence spectra. No significant change in the absorption spectra of the quinones is also observed in the presence of the amines. For all the quinone-amine pairs, the bimolecular quenching constants (kq) estimated from SS and time-resolved measurements are found to be similar. Variation in the kq values with the oxidation potentials of the amines indicates the involvement of the ET mechanism for the quenching process. A reasonably good correlation between the kq values and the free energy changes (deltaG0) for the ET reactions following Marcus' outer-sphere ET theory also supports this mechanism. It is seen that for both the quinone-ArA and quinone-AlA systems, the kq values initially increase and then get saturated at some diffusion-controlled limiting values (kqDC) as deltaG0 values gradually become more negative. Interestingly, however, it is seen that the kqDC value for the quinone-AlA systems is substantially lower than that for quinone-ArA systems. Such a large difference in the kqDC values between quinone-AlA and quinone-ArA systems is quite unusual. Present results have been rationalized based on the assumption that an orientational restriction is imposed for the encounter complexes in quinone-AlA systems to undergo ET reactions, which arises because of the localized (at amino nitrogen) shapes of the highest-occupied molecular orbitals (HOMO) of AlA in comparison to the pi-like HOMO of the ArA.

Amines↗
PubMed2003

Effect of solvent viscosity, polarity and pH on the charge transfer between tryptophan radical and tyrosine in bovine serum albumin: a pulse radiolysis study.

The effect of viscosity, solvent polarity and pH of the medium on the reaction of a protein, bovine serum albumin (BSA), with organohalo-peroxyl radical in aqueous solution has been studied using pulse radiolysis technique. Unlike in dilute aqueous solution, electron transfer from tyrosine to tryptophan radical in BSA has been clearly observed at a viscosity of 7.7 centiPoise (cP). The oxidation of BSA, tryptophan and tyrosine in different media has also been compared with those taking place in dilute aqueous solution. The effect of solvent characteristics on the observed charge transfer has been discussed.

Animals↗
PubMed2003

Antioxidant activity of bakuchiol: experimental evidences and theoretical treatments on the possible involvement of the terpenoid chain.

The protective activity of the plant-derived meroterpene, bakuchiol [1-(4-hydroxyphenyl)-3,7-dimethyl-3-vinyl-1,6-octadiene, 1], against oxidative damages to lipids and proteins has been investigated and rationalized based on the scavenging activity of 1 against various oxidizing radicals (Cl(3)CO(2)(*), linoleic acid peroxyl radicals, LOO(*), DPPH radicals, (*)OH, and glutathiyl radicals). The rate constants of the scavenging reactions, transients formed in these reactions, and their mechanistic pathways have been probed using optical pulse radiolysis technique. Besides 1, its methyl ether derivative 2 also could prevent lipid peroxidation in rat brain homogenate, indicating the probable participation of their terpenoid chains in scavenging LOO(*). This was further corroborated from the pulse radiolytic studies on the reaction between the glutathiyl radicals and the compounds 1 and 2 as well as two other congeners, 3 and 4, which showed transient absorptions at approximately 300 nm attributable to some C-centered allylic radicals. On the basis of the strong signals at approximately 300 nm with 1-3 as compared to compound 4, formation of the allylic radical adjacent to the trisubstituted olefin function in 1-3 was envisaged. This was confirmed by quantum chemical calculations of the relative energies of the probable radical species derivable from 2 using Hartree-Fock and density functional theory along with self-consistent reaction field model. In the case of 1, the allylic radical was found to be transformed into the phenoxyl radical at a later stage. All of these data revealed, for the first time, the importance of the terpenoid moiety of bakuchiol in controlling its antioxidant action via radical scavenging.

Animals↗
PubMed2001

Free radical scavenging behavior of folic acid: evidence for possible antioxidant activity.

The free radical scavenging properties and possible antioxidant activity of folic acid are reported. Pulse radiolysis technique is employed to study the one-electron oxidation of folic acid in homogeneous aqueous solution. The radicals used for this study are CCl(3)O(2)(*), N(3)(*), SO(4)(*-), Br(2)(*-), *OH, and O(*-). All these radicals react with folic acid under ambient condition at an almost diffusion-controlled rate producing two types of transients. The first transient absorption maximum is around 430 nm, which decays, and a simultaneous growth at around 390 nm is observed. Considering the chemical structure of folic acid, the absorption maximum at 430 nm has been assigned to a phenoxyl radical. The latter one is proposed to be a delocalized molecular radical. A permanent product has been observed in the oxidation of folic acid with CCl(3)O(2)(*) and N(3)(*) radicals, with a broad absorption band around 370-400 nm. The bimolecular rate constants for all the radical-induced oxidation reactions of folic acid have been measured. Folic acid is seen to scavenge these radicals very efficiently. In the reaction of thiyl radicals with folic acid, it has been observed that folic acid can not only scavenge thiyl radicals but can also repair these thiols at physiological pH. While carrying out the lipid peroxidation study, in spite of the fact that folic acid is considerably soluble in water, we observed a significant inhibition property in microsomal lipid peroxidation. A suitable mechanism for oxidation of folic acid and repair of thiyl radicals by folic acid has been proposed.

Animals↗
PubMed2001

Does increasing ovum donor compensation lead to differences in donor characteristics?

OBJECTIVE: To evaluate the effects of a compensation increase for anonymous ovum donors on demographic and social characteristics. DESIGN: Retrospective analysis. SETTING: The Mount Sinai Medical Center Ovum Donation Program. PATIENT(S): All program applicants for 2 years preceding (group I, n = 2,934) and 1 year following an increase in donor compensation (group II, n = 1,114; total N = 4,048). INTERVENTION(S): Compensation was increased from $2,500 to $5,000 per cycle. MAIN OUTCOME MEASURE(S): Demographic and social characteristics of applicants and donors. RESULT(S): More group II applicants (65.7%) than group I applicants (49.2%) returned an initial biographical questionnaire. Compensation level did not affect the percentage rejected at any stage in the application process or ultimately selected. There were no differences in donors in age, marital status, education, race, religion, or psychological profile. Group II donors had more previous pregnancies (group II mean = 1.2, group I mean = 0.6) and previous abortions (group II mean = 0.8, group I mean = 0.4). CONCLUSION(S): Increasing compensation may result in a higher percentage of potential donors completing an initial questionnaire but does not alter the demographic and social characteristics of selected donors. Adherence to a rigorous applicant screening ensures that donor characteristics remain independent from compensation.

Abortion, Induced↗
PubMed2001

Three-dimensional measurement of gestational and yolk sac volumes as predictors of pregnancy outcome in the first trimester.

Along with crown-rump length (CRL), the size (diameter) of embryonic structures such as gestational sac (GS) and yolk sac (YS) may have prognostic value for embryonic development. We proposed that first-trimester volume calculations of these structures using transvaginal three-dimensional ultrasound technique may have value as predictors of adverse reproductive outcome. Forty-nine consecutive patients (treated for infertility) with singleton pregnancies were included in this prospective study. Seventy-three examinations were performed in case of pregnancies with normal, and 12 with abnormal outcome. GS and YS volumes were plotted against gestational age (GA) (25-65 days post ovulation) to create nomograms for normal outcome and the same procedure was carried out with CRL measurements as well. Measurements of abnormal pregnancies were compared with these nomograms. Specificity, sensitivity, positive and negative predictive values were also calculated. Regression analysis revealed a power correlation between GS volumes and GA, logarithmic relationship was observed when YS volumes were plotted against GA. CRL showed logarithmic correlation with GA as well. Both GS volumetry and CRL measurements proved to have statistically significant predictive value for adverse outcome (p<0.05). However, no statistically significant difference was found when YS volumes of normal and abnormal pregnancies were compared. Specificity, sensitivity, positive and negative predictive values of GS volumes and CRL were similar. Mean YS/GS ratios also had good predictive values (p<0.05). Volume determination of YS and GS can be performed quickly and simply applying three-dimensional sonography. Volumetry of GS proved to be a sensitive predictor for pregnancy outcome and can be a good supplement to CRL measurements.

Embryonic and Fetal Development↗
PubMed2000

Pulse radiolytic oxidation of beta-carotene with halogenated alkylperoxyl radicals in a quaternary microemulsion: formation of retinol.

Pulse radiolytically generated halogenated alkylperoxyl radicals, namely CCl3OO*, CBr3OO*, CHCl2OO*, CHBr2OO*, etc. have been employed for a study of the oxidation of beta-carotene in a quaternary microemulsion. All these halogenated alkylperoxyl radicals produce a radical cation (absorption maximum at 840 nm), either via the initial formation of an adduct (absorption maximum at 740 nm), or by direct reaction. There was a considerable blue shift of both absorption peaks in the present system as compared to those earlier reported in non-polar as well as in micellar media. An additional intense absorption peak at approximately 345 nm was noted at a longer time scale and was stable up to 5 ms. On irradiation with a large number of electron pulses, a stable product with an absorption maximum at 315 nm appeared. On excitation at 315 nm, this product gave a fluorescence spectrum with an emission maximum at 525 nm. The absorption and fluorescence spectra of the stable product compared with those of retinol; this was further confirmed by HPLC analysis. A suitable mechanism has been proposed.

Animals↗
PubMed2000

Leishmania plasma membrane Mg2+-ATPase is a H+/K+-antiporter involved in glucose symport. Studies with sealed ghosts and vesicles of opposite polarity.

Experiments from other laboratories conducted with Leishmania donovani promastigote cells had earlier indicated that the plasma membrane Mg2+-ATPase of the parasite is an extrusion pump for H+. Taking advantage of the pellicular microtubular structure of the plasma membrane of the organism, we report procedures for obtaining sealed ghost and sealed everted vesicle of defined polarity. Rapid influx of H+ into everted vesicles was found to be dependent on the simultaneous presence of ATP (1 mm) and Mg2+ (1 mm). Excellent correspondence between rate of H+ entry and the enzyme activity clearly demonstrated the Mg2+-ATPase to be a true H+ pump. H+ entry into everted vesicle was strongly inhibited by SCH28080 (IC50 = approximately 40 microm) and by omeprazole (IC50 = approximately 50 microm), both of which are characteristic inhibitors of mammalian gastric H+,K+-ATPase. H+ influx was completely insensitive to ouabain (250 microm), the typical inhibitor of Na+,K+-ATPase. Mg2+-ATPase activity could be partially stimulated with K+ (20 mm) that was inhibitable (>85%) with SCH28080 (50 microm). ATP-dependent rapid efflux of 86Rb+ from preloaded vesicles was completely inhibited by preincubation with omeprazole (150 microm) and by 5,5'-dithiobis-(2-nitrobenzoic acid) (1 mm), an inhibitor of the enzyme. Assuming Rb+ to be a true surrogate for K+, an ATP-dependent, electroneutral stoichiometric exchange of H+ and K+(1:1) was established. Rapid and 10-fold active accumulation of [U-(14)C]2-deoxyglucose in sealed ghosts could be observed when an artificial pH gradient (interior alkaline) was imposed. Rapid efflux of [U-(14)C]d-glucose from preloaded everted vesicles could also be initiated by activating the enzyme, with ATP. Taken together, the plasma membrane Mg2+-ATPase has been identified as an electroneutral H+/K+ antiporter with some properties reminiscent of the gastric H+,K+-ATPase. This enzyme is possibly involved in active accumulation of glucose via a H+-glucose symport system and in K+ accumulation.

Adenosine Triphosphate↗
PubMed2000

Stage-specific development of a novel adenosine transporter in Leishmania donovani amastigotes.

Leishmania donovani, like all other kinetoplastida, is a purine auxotroph. Comparative studies of adenosine transport in L. donovani amastigotes and promastigotes revealed that, unlike the promastigote stage, the amastigote possesses two distinct adenosine transporters (T(1) and T(2)) both with high affinities (K(m), 1.14+/-0.05 and 2. 09+/-0.13 microM, respectively). One of these transporters (T(1)) appears to be identical with the adenosine/pyrimidine nucleoside transporter of the promastigote reported earlier. The other transporter (T(2)) is specific for the amastigote stage and transports only purine nucleosides. The biological significance of this stage-specific development of the second adenosine transporter has been briefly discussed.

Adenosine↗
PubMed2000

Molecular cytogenetic analysis of uterine leiomyoma and leiomyosarcoma by comparative genomic hybridization.

Uterine leiomyomata are among the most common of human neoplasms and are associated with abnormal uterine bleeding, infertility, and abdominal pain. Uterine leiomyosarcomata are presumed to be the malignant counterpart to uterine leiomyomata and are very rare. Transformation of uterine leiomyoma (ULM) into uterine leiomyosarcoma (ULMS) is yet to be conclusively confirmed, and each type of tumor may represent a distinct genetic entity. We used comparative genomic hybridization (CGH) to evaluate DNA sequence copy-number changes in 12 specimens of ULM and 8 of ULMS. CGH analysis of ULM demonstrated chromosomal imbalances in 8 of 12 (66. 7%) specimens. The most frequent ULM gains were observed at 9q34 (a novel finding) and on chromosome 19. Other ULM imbalances included gains and losses of chromosome 1p, losses on 7q, and gains on 12q. All ULMS specimens demonstrated chromosomal aberrations. Chromosome 1 imbalances were very prominent. The most frequent losses were detected on 14q and 22q. Losses on 14q are rarely seen in other types of leiomyo-sarcoma and may be a distinctive feature of ULMS. Gains on chromosomes 8, 17, and X were observed in half the cases and were accompanied by high-level amplification. Other chromosome arms overrepresented included 12q and 19p. The absence of specific anomalies common to all ULM and ULMS argues against their being benign-malignant counterparts.

Chromosome Aberrations↗
PubMed2000

Effect of solvent on the excited-state photophysical properties of curcumin.

Photophysical properties of curcumin, 1,7-bis-(4-hydroxy-3-methoxy phenyl)-1,6-heptadiene-2,5-dione, a pigment found in the rhizomes of Curcuma longa (turmeric) have been studied in different kinds of organic solvent and also in Triton X-100 aqueous micellar media using time-resolved fluorescence and transient absorption techniques having pico and nanosecond time resolution, in addition to steady-state absorption and fluorescence spectroscopic techniques. Steady-state absorption and fluorescence characteristics of curcumin have been found to be sensitive to the solvent characteristics. Large change (delta mu = 6.1 Debye) in dipole moments due to photoexcitation to the excited singlet state (S1) indicates strong intramolecular charge transfer character of the latter. Curcumin is a weakly fluorescent molecule and the fluorescence decay properties in most of the solvents could be fitted well to a double-exponential decay function. The shorter component having lifetime in the range 50-350 ps and percent contribution of amplitude more than 90% in different solvents may be assigned to the enol form, whereas the longer component, having lifetime in the range 500-1180 ps with less than 10% contribution may be assigned to the di-keto form of curcumin. Our nuclear magnetic resonance study in CDCl3 and dimethyl sulfoxide-D6 also supports the fact that the enol form is present in the solution by more than about 95% in these solvents. Excited singlet (S1) and triplet (T1) absorption spectrum and decay kinetics have been characterized by pico and nanosecond laser flash photolysis. Quantum yield of the triplet is low (phi T < or = 0.12). Both the fluorescence and triplet quantum yields being low (phi f + phi T < 0.18), the photophysics of curcumin is dominated by the energy relaxation mechanism via the internal conversion process.

Curcumin↗
PubMed1999

Elevated day 3 serum follicle stimulating hormone and/or estradiol may predict fetal aneuploidy.

OBJECTIVE: To determine whether baseline serum FSH and/or E2 concentrations can predict the risk for fetal chromosomal abnormalities. DESIGN: Case control study. SETTING: Reproductive technology program at a university hospital. PATIENT(S): Patients who underwent dilation and curettage (D + C), and whose products of conception were karyotyped. INTERVENTION(S): Patients underwent natural conception or controlled ovarian hyperstimulation followed by intrauterine insemination, in vitro fertilization and embryo transfer, gamete intrafallopian transfer, or zygote intrafallopian transfer. MAIN OUTCOME MEASURE(S): Baseline serum FSH and E2 concentrations and fetal karyotype. RESULT(S): Genetic evaluation of 78 D + C specimens revealed 34 normal and 44 abnormal fetal karyotypes. A significantly greater proportion of women with abnormal fetal karyotype had elevated baseline serum FSH (> or =15 mIU/mL [RIA] or 10 mIU/mL [Immulite]) and/or E2 > or = 50 pg/mL [Immulite]) compared with women of normal fetal karyotype. Among karyotypically abnormal abortuses, autosomal trisomy was the most common abnormality noted (79.5%), followed by mosaicism (6.8%), triploidy (6.8%), monosomy XO (4.5%), and balanced translocation (2.3%). CONCLUSION(S): Baseline serum FSH and/or E2 concentrations may be valuable as predictors of fetal aneuploidy.

Abortion, Missed↗
PubMed1999

Diagnosing amnionicity at 6 weeks of pregnancy with transvaginal three-dimensional ultrasonography: case report.

OBJECTIVE: To report a case of monochorionic, diamniotic twin pregnancy diagnosed at 6 weeks of pregnancy with three-dimensional (3D) transvaginal sonography and to discuss the use of this diagnostic method in the evaluation of multifetal pregnancy in the first trimester. DESIGN: Case report. SETTING: University-based IVF program. PATIENT(S): A 30-year-old ovum recipient underwent ultrasonographic evaluation of a first-trimester twin pregnancy. INTERVENTION(S): Two-dimensional (2D) and 3D transvaginal sonography. MAIN OUTCOME MEASURE(S): Accurate diagnosis of chorionicity and amnionicity. RESULT(S): Monoamniotic pregnancy and conjoined twinning could not be ruled out by using 2D transvaginal sonography at 6 weeks, because only one yolk sac (YS) and no membranes could be visualized, and the two embryos were closely positioned within one gestational sac. Applying 3D technique, two YSs and two separate embryos could clearly be observed, establishing the correct diagnosis of a monochorionic, diamniotic pregnancy. CONCLUSION(S): The 3D transvaginal ultrasonography provides a quick and accurate diagnostic modality for the evaluation of a first-trimester multiple gestation.

Adult↗
PubMed1999

Antioxidant properties of melatonin: a pulse radiolysis study.

Various one-electron oxidants such as OH*, tert-BuO*, CCl3OO*, Br2*- and N3*, generated pulse radiolytically in aqueous solutions at pH 7, were scavenged by melatonin to form two main absorption bands with lambda(max) = 335 nm and 500 nm. The assignment of the spectra and determination of extinction coefficients of the transients have been reported. Rate constants for the formation of these species ranged from 0.6-12.5x10(9) dm3 mol(-1) s(-1). These transients decayed by second order, as observed in the case of Br2*- and N3* radical reactions. Both the NO2* and NO* radicals react with the substrate with k = 0.37x10(7) and 3x10(7) dm3 mol(-1) s(-1), respectively. At pH approximately 2.5, the protonated form of the transient is formed due to the reaction of Br2*- radical with melatonin, pKa ( MelH* <=> Mel* + H+) = 4.7+/-0.1. Reduction potential of the couple (Mel*/MelH), determined both by cyclic voltammetric and pulse-radiolytic techniques, gave a value E(1)7 = 0.95+/-0.02 V vs. NHE. Repair of guanosine radical and regeneration of melatonin radicals by ascorbate and urate ions at pH 7 have been reported. Reactions of the reducing radicals e(aq)- and H* atoms with melatonin have been shown to occur at near diffusion rates.

Antioxidants↗
PubMed1999

The use of propofol, nitrous oxide, or isoflurane does not affect the reproductive success rate following gamete intrafallopian transfer (GIFT): a multicenter pilot trial/survey.

BACKGROUND: Whether anesthetic agents administered during gamete intrafallopian transfer (GIFT) affect reproductive outcome is controversial. This multicenter pilot trial and survey had two purposes: to evaluate the effect of propofol, nitrous oxide, midazolam, and isoflurane on pregnancy outcome after GIFT, and to determine if a larger prospective, randomized study is warranted. METHODS: A written invitation was mailed to all 50 fertility programs in the United States that are members of the Society for Assisted Reproductive Technology and perform more than 30 GIFT procedures per year. They were invited to contribute information from the medical records of women who underwent GIFT during the calendar years 1993 and 1994. They were asked to document whether propofol, nitrous oxide, midazolam, a potent inhaled anesthetic agent was used during the GIFT procedure; if the woman became pregnant; and if she delivered at least one live neonate. RESULTS: Seven medical centers participated and contributed data from 455 women. The clinical pregnancy rate (number of pregnancies/total number of GIFT procedures) and the delivery rate (number of women who delivered at least one live baby/total number of GIFT procedures) were 35% and 32%, respectively. A statistically significant difference could not be found in the clinical pregnancy or delivery rates between those women who received propofol, nitrous oxide, midazolam, or isoflurane during GIFT and those who did not. CONCLUSIONS: No agent-related differences in pregnancy rates were found when propofol, nitrous oxide, isoflurane, or midazolam was used as part of the anesthetic technique for GIFT. Therefore, a more extensive prospective trial does not appear to be warranted.

Adult↗