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Chakrabarti A, Dasgupta C. A Monte Carlo study of realistic models of metallic spin glasses. ACTA ACUST UNITED AC 2000. [DOI: 10.1088/0022-3719/21/8/033] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Chakrabarti A. A comparative study of aminophylline and acepifylline on reversal phenomenon of anticonvulsant drug efficacy in electroshock model of seizures in rats. BOLLETTINO CHIMICO FARMACEUTICO 2000; 139:270-5. [PMID: 11213435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
The study was designed to compare the proconvulsive activity of two theophylline-containing bronchodilating agents, aminophylline and acepifylline and their antagonistic effects to diazepam, phenytoin, MK-801 and carbamazepine in electroshock seizure model in rats. Graded intensity (30-150 mA for 0.2 s) of electroshock was applied to different groups of rats pretreated either with normal saline (0.5 ml, i.p.), graded doses (25-150 mgkg-1, i.p.) of aminophylline, graded doses (70-560 mgkg-1, i.p.) of acepifylline, graded doses of the antiseizure drugs or to rats pretreated with aminophylline (25 mgkg-1, i.p.) + antiseizure drugs or acepifylline (70 mgkg-1, i.p.) + antiseizure drugs. CI 50 +/- s.e.m. value was 88.41 +/- 2.14 mA in saline treated rats. In aminophylline pretreated rats the values were 84.14 +/- 2.03, 68.06 +/- 1.24, 54.28 +/- 1.96 and 39.58 +/- 2.31 mA at 25 mgkg-1 (0.06 mmolekg-1), 50 mgkg-1 (0.12 mmolekg-1), 100 mgkg-1 (0.24 mmolekg-1) and 150 mgkg-1 (0.36 mmolekg-1), i.p. doses respectively. The values were 85.73 +/- 1.09, 64.86 +/- 2.37, 61.58 +/- 1.37 and 60.62 +/- 2.41 mA at 70 mgkg-1 (0.125 mmolekg-1), 140 mgkg-1 (0.25 mmolekg-1), 280 mgkg-1 (0.50 mmolekg-1) and 560 mgkg-1 (1.0 mmolekg-1), i.p. doses respectively for the acepifylline pretreated groups of rats. Diazepam, MK-801, phenytoin and carbamazepine significantly antagonized electroshock-induced seizure in a dose-dependent manner. Subsensitizing dose of aminophylline (25 mgkg-1, i.p.) but not that of acepifylline (70 mgkg-1, i.p.) pretreatment significantly antagonized the efficacy of all the antiseizure drugs. The study highlighted that acepifylline might be safely used in epileptic patients well controlled on antiepileptic drugs. Aminophylline, on the other hand, should be avoided since it might produce breakthrough seizure attacks due to its greater proconvulsive and anti-antiseizure drug effects.
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Chakrabarti A, Sharma SC. Paranasal sinus mycoses. THE INDIAN JOURNAL OF CHEST DISEASES & ALLIED SCIENCES 2000; 42:293-304. [PMID: 15597677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
The incidence of paranasal sinus mycoses (fungal sinusitis) varies widely with higher frequency in Sudan, southwestern states of USA and north India, which have hot and dry climate. The disease has been described as having four types: allergic, non-invasive, invasive and fulminate. A possible fifth type: non-invasive destructive may also exist. In a prospective study of 176 cases of fungal sinusitis from our centre, on the basis of clinical, radiological, histopathologic and mycologic findings the patients could be categorized into: allergic (12), non-invasive without bone destruction (81), non-invasive destructive (16), chronic invasive (55) and fulminant (12) types. Except the fulminate variety, the disease is commonly found in young immuno-competent population of rural areas. Aspergillus spp. are the commonest etiological agents though the importance of dematiaceous fungi in allergic fungal sinusitis has been stressed. Zygomycetes are common agents in fulminate type. In our series A. flavus (80%) was the commonest isolate, followed by A.fumigatus (9.7%), Rhizopus arrhizus (6.3%) and Alternaria spp. (1.1%). Curvularia lunata, Apophysomyces elegans and Candida albicans were isolated from one patient each. Different host and environmental factors may help in lodging the causal fungi in mucosal plugs of these patients. Fungal allergy is associated with all varieties of the disease. But it is not clear what determines the invasion of mucosa. Rabbit can be used as an animal model. Histopathology and radio-imaging techniques help to distinguish different types and delineate extension of disease process. Culture helps to identify the responsible etiological agent. The presence or absence of precipitating antibody correlates well with disease progression or recovery. For effective management, non-invasive disease requires surgical debridement and sinus ventilation only. But for invasive type the need of adjuvant medical therapy is recommended to prevent recurrence and further extension. Itraconazole was found to be most useful in our study to prevent recurrence. Patients with fulminate type require radical surgery and immediate chemotherapy.
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Jindal SK, Gupta D, Aggarwal AN, Chakrabarti A. The spectrum of respiratory mycoses in a referral hospital in north-western India. THE INDIAN JOURNAL OF CHEST DISEASES & ALLIED SCIENCES 2000; 42:289-92. [PMID: 15597676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
There has been an increasing recognition of respiratory mycoses in this country in the recent past. Candidiasis, aspergillosis and cryptococcosis have been reported from different centres. Occasional cases of histoplasmosis and sporotrichosis have also been reported. Infections with Pneumocystis carinii, which is now classified as a fungus, are being frequently diagnosed, especially in the immuno-compromised patients such as those on prolonged immunosuppressive therapy or with HIV infection. Although the clinical picture of respiratory mycoses resembles that of any other infection, the presentation in several cases is atypical and the diagnosis is delayed. In a review of our patients of respiratory fungal infections seen in the last few years, we found several interesting examples. We report here the general clinical spectrum of respiratory mycoses and some interesting cases seen at our Centre.
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Gupta A, Gupta V, Dogra MR, Chakrabarti A, Ray P, Ram J, Patnaik B. Fungal endophthalmitis after a single intravenous administration of presumably contaminated dextrose infusion fluid. Retina 2000; 20:262-8. [PMID: 10872931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
PURPOSE To report fungal endophthalmitis in nonimmunocompromised patients, each of whom received a single intravenous administration of presumably contaminated dextrose infusion fluid for minor ailments in rural settings. METHODS This noncomparative case series included 12 nonimmunocompromised patients (12 eyes) with culture-positive fungal endophthalmitis. All eyes underwent initial vitreous tap with injection of intravitreal antibiotics. Eleven eyes required pars plana vitrectomy and oral fluconazole or itraconazole for 4 to 6 weeks. One patient with panophthalmitis was treated with intravenous amphotericin B. To support the hypothesis that contaminated intravenous fluid was the possible risk factor, samples from 72 sealed bottles of 5% dextrose were subjected to fungal culture. RESULTS Patients presented 1 to 11 weeks (mean, 4.6 weeks) after the intravenous infusion. All eyes had a positive smear and cultures for fungi. Aspergillus specimen was isolated in nine eyes, Candida in two eyes, and Mucor in one eye. Final visual acuity was 20/80 or better in 8 (66.6%) eyes. Eleven of the 72 samples from dextrose bottles were culture-positive for fungi: six for Aspergillus fumigatus, three for Aspergillus niger, and two for Candida albicans. CONCLUSION A presumed contaminated intravenous infusion administered in a rural setting was found as a new risk factor for development of endogenous fungal endophthalmitis. These patients were successfully treated with pars plana vitrectomy and oral fluconazole and itraconazole therapy.
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Podariu I, Shou Z, Chakrabarti A. Viscous flow and coarsening of microdomains in diblock copolymer thin films. PHYSICAL REVIEW. E, STATISTICAL PHYSICS, PLASMAS, FLUIDS, AND RELATED INTERDISCIPLINARY TOPICS 2000; 62:R3059-R3062. [PMID: 11088878 DOI: 10.1103/physreve.62.r3059] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2000] [Indexed: 05/23/2023]
Abstract
For thin block copolymer (BCP) films on a homogeneous substrate, a fast domain growth exponent has recently been observed in experiments. This growth exponent is larger than what one would expect from theoretical considerations of two-dimensional coarsening of small molecular liquid mixtures in the viscous regime. Thus it is not clear whether the growth kinetics is truly different for block copolymer films, or if the observed anomalous exponent is a result of a possible dimensional crossover from two to three dimensions. To address part of this question, we have carried out numerical simulations of ordering and domain growth in a two-dimensional system of BCP melts. The model calculations reported here explicitly include viscous, hydrodynamic flow and provide a scaling description of the growth of domains in a quenched BCP system. Our results indicate that the growth kinetics of BCP melts in two dimensions belong to the same dynamical universality class of small molecular liquid mixtures in the viscosity dominated regime.
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Chakrabarti A, Sharma A, Sood A, Grover R, Sakhuja V, Prabhakar S, Varma S. Changing scenario of cryptococcosis in a tertiary care hospital in north India. Indian J Med Res 2000; 112:56-60. [PMID: 11037679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023] Open
Abstract
BACKGROUND & OBJECTIVES With the increase in the number of patients of AIDS, the incidence of cryptococcosis is on the rise in India. It was therefore considered important to evaluate the predisposing factors, laboratory investigations and outcome of patients with cryptococcosis in this changed scenario. METHODS We assessed 58 patients with cryptococcosis retrospectively over a five year period (January 1995-December 1999) at the Nehru Hospital, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh. RESULTS The annual incidence of cryptococcosis in PGIMER, Chandigarh has increased about 15 fold from 1970-1982 (pre AIDS era) to 1995-1999 (present series). Of the 47 patients studied for predisposing factors, 36 patients were identified with predisposing factors, HIV infection (57.4%) was the commonest followed by haematologic malignancies (6.3%) and renal transplant (4.2%). Forty one patients were diagnosed by isolation of the organism as well as antigen detection in cerebrospinal fluid/serum, 9 by isolation alone and 8 by antigen detection alone. Quantitative antigen titres were done in 38 patients and a significantly higher (P < 0.01) antigen titre (> 512) was observed in HIV positive patients as compared to HIV negative patients. All isolates tested were of Cryptococcous neoformans var neoformans biotype and no resistance to antifungal agents was noted. Twenty of 41 patients receiving treatment improved. The results were compared with other studies available from India. INTERPRETATION & CONCLUSION The incidence of cryptococcosis is on the rise in this part of north India and this can be attributed to an increase in AIDS cases.
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Abstract
PURPOSE To study the results of phacoemulsification in eyes with white cataract. SETTING Aravind Eye Hospital, Madurai, India. METHODS This retrospective study comprised 212 consecutive patients with white cataract: 192 mature (90.6%), 11 intumescent (5.2%), and 9 hypermature (4.2%). Patients had phacoemulsification and continuous curvilinear capsulorhexis. After the nucleus was removed by the divide and conquer or the phaco chop technique, a posterior chamber intraocular lens was implanted. Preoperative and intraoperative findings, as well as postoperative outcomes, were analyzed. RESULTS Intraoperative complications included premature entry of the tunnel into the anterior chamber in 4 eyes (1.9%), incomplete capsulorhexis in 60 (28.3%), posterior capsular tear in 4 (1.9%), conversion to a manual nonphacoemulsification technique in 4 (1.9%), intraoperative miosis in 7 (3.3%), and iris chafing in 2 (0.9%). Mean phacoemulsification time was 2.03 minutes (range 0 to 5.8 minutes). A best corrected visual acuity of 6/9 or better was attained in 131 patients (61.8%) on the first postoperative day and in 199 patients (93.9%) at 1 month. Postoperative complications included moderate transient striate keratopathy with corneal edema in 12 eyes (5.7%) and iritis in 2 (0.9%). CONCLUSIONS Phacoemulsification was a safe and effective technique to remove white mature cataract in eyes in a developing country.
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Pereira GG, Williams DRM, Chakrabarti A. Interfacial profiles of mismatched lamellae in thin diblock copolymer films. J Chem Phys 2000. [DOI: 10.1063/1.481636] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Schatten H, Hueser CN, Chakrabarti A. From fertilization to cancer: the role of centrosomes in the union and separation of genomic material. Microsc Res Tech 2000; 49:420-7. [PMID: 10842368 DOI: 10.1002/(sici)1097-0029(20000601)49:5<420::aid-jemt3>3.0.co;2-v] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Centrosomes play crucial roles in the union of sperm and egg nuclei during fertilization and in the equal separation of genomic material during cell division. While many studies in recent years have focused on the molecular composition of centrosomes, this article focuses on the structural behavior of centrosomes and on factors that play a role in centrosome functions under normal, artificially altered, and abnormal conditions. We review here how studies in the classic sea urchin egg model have contributed to our knowledge on the centrosome cycle within the cell cycle, on compaction and decompaction of centrosomal material, and on the contributions of maternal and paternal centrosomes during fertilization. Centrosome material is activated in unfertilized eggs by increasing pH with ammonium and by increasing calcium with the ionophore A23187, which are conditions that are normally induced by sperm. D(2)O and taxol also induce centrosome aggregation in the unfertilized egg. Maternal and paternal centrosome material both contribute to the formation of a functional centrosome but the formation of a bipolar centrosome requires material from the paternal centrosome. Fertilization of taxol-treated eggs reveals that the male centrosome possesses the capability to attract maternal centrosome material. When pronuclear fusion of the male and female pronuclei is inhibited with agents such as the disulfide reducing agent dithiothreitol (DTT) a bipolar mitotic apparatus is formed from the paternal centrosome. Furthermore, one centrosome of the bipolar mitotic apparatus is capable of organizing an additional half spindle that attaches to the female pronucleus indicating a functional and perhaps structural connection between centrosomes and chromatin. Sea urchin eggs are also useful to study centrosome abnormalities and consequences for the cell cycle. While classic studies by Theodor Boveri have shown that dispermic fertilization will result in abnormal cell division because of multiple centrosomes contributed by sperm, abnormal cell division can also be induced by chemical alterations of centrosomes. Compaction and decompaction of centrosome structure is studied using chloral hydrate or the chaotropic agent formamide, which reveals that centrosomes can be chemically altered to produce mono- or multipolar abnormal mitosis and unequal distribution of genomic material upon release from formamide. The patterns of abnormal centrosome reformations after recovery from formamide treatment resemble those seen in cancer cells which argues that structural defects of centrosomes can account for the formation of abnormal mitosis and multipolar cells frequently observed in cancer. In summary, the sea urchin model has been most useful to gain information on the role of centrosomes during fertilization and cell division as well as on adverse conditions that play a role in centrosome dysfunctions and in disease.
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Chakrabarti A. On the solution of the problem of scattering of surface–water waves by the edge of an ice cover. Proc Math Phys Eng Sci 2000. [DOI: 10.1098/rspa.2000.0552] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Schatten H, Chakrabarti A, Taylor M, Sommer L, Levine H, Anderson K, Runco M, Kemp R. Effects of spaceflight conditions on fertilization and embryogenesis in the sea urchin Lytechinus pictus. Cell Biol Int 2000; 23:407-15. [PMID: 10623420 DOI: 10.1006/cbir.1999.0371] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Calcium loss and muscle atrophy are two of the main metabolic changes experienced by astronauts and crew members during exposure to microgravity in space. Calcium and cytoskeletal events were investigated within sea urchin embryos which were cultured in space under both microgravity and 1 g conditions. Embryos were fixed at time-points ranging from 3 h to 8 days after fertilization. Investigative emphasis was placed upon: (1) sperm-induced calcium-dependent exocytosis and cortical granule secretion, (2) membrane fusion of cortical granule and plasma membranes; (3) microfilament polymerization and microvilli elongation; and (5) embryonic development into morula, blastula, gastrula, and pluteus stages. For embryos cultured under microgravity conditions, the processes of cortical granule discharge, fusion of cortical granule membranes with the plasma membrane, elongation of microvilli and elevation of the fertilization coat were reduced in comparison with embryos cultured at 1 g in space and under normal conditions on Earth. Also, 4% of all cells undergoing division in microgravity showed abnormalities in the centrosome-centriole complex. These abnormalities were not observed within the 1 g flight and ground control specimens, indicating that significant alterations in sea urchin development processes occur under microgravity conditions.
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Banerjee M, Chakrabarti A, Acharya DP, Roy A, Chakrabarty AN, Bhattacharyya J, Dastidar SG. Validity of mechanism of gene transfer in the process called conjugation in bacteria. INDIAN JOURNAL OF EXPERIMENTAL BIOLOGY 2000; 38:160-6. [PMID: 11218833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
We have attempted a new evaluation of the process of conjugation in bacteria, because of some basic dissimilarities observed between this and that of eukaryotes, or plants and animals. Reference donor and recipient strains, widely used to prove conjugation in bacteria, were chosen; addition of DNase during the conjugation process, led to an unexpected but highly reproducible increase in the transconjugant colony counts (TCC; ca. > or = 1 log), when compared with that of the controls without DNase. Transconjugants were also obtained when the same live donors were substituted with the UV-killed ones although the TCC was very low initially. Contrarily, donors treated with DNA-intercalating agents, e.g. acridine orange or ethidium bromide, resulted in a complete failure to produce transconjugants. There was a quantitative relationship between the DNase used on donors and levels of DNA sugars/nucleotides/DNA, which possibly resulted from interaction between the DNase and DNA being present/produced on the donor surface. This may be indicative of what may actually happen in the donor-recipient mixtures in the conjugation test proper, where the recipient DNase may activate a donor DNA production cycle. The evidences presented did not suggest that the donor DNA in the conjugation process is actually vestibuled through any intercellular conjugation passages, and is susceptible to the action of DNase or the intercalating dyes.
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Bhattacharya SK, Bhattacharya A, Chakrabarti A. Adaptogenic activity of Siotone, a polyherbal formulation of Ayurvedic rasayanas. INDIAN JOURNAL OF EXPERIMENTAL BIOLOGY 2000; 38:119-28. [PMID: 11218827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
Siotone (ST) is a herbal formulation comprising of Withania somnifera, Ocimum sanctum, Asparagus racemosus, Tribulus terristris and shilajit, all of which are classified in Ayurveda as rasayanas which are reputed to promote physical and mental health, improve defence mechanisms of the body and enhance longevity. These attributes are similar to the modern concept of adaptogenic agents, which are, known to afford protection of the human physiological system against diverse stressors. The present study was undertaken to investigate the adaptogenic activity of ST against chronic unpredictable, but mild, footshock stress induced perturbations in behaviour (depression), glucose metabolism, suppressed male sexual behaviour, immunosuppression and cognitive dysfunction in CF strain albino rats. Gastric ulceration, adrenal gland and spleen weights, ascorbic acid and corticosterone concentrations of adrenal cortex, and plasma corticosterone levels, were used as the stress indices. Panax ginseng (PG) was used as the standard adaptogenic agent for comparison. Additionally, rat brain levels of tribulin, an endogenous endocoid postulated to be involved in stress, were also assessed in terms of endogenous monoamine oxidase (MAO) A and MAOB inhibitory activity. Chronic unpredictable footshock induced marked gastric ulceration, significant increase in adrenal gland weight and plasma corticosterone levels, with concomitant decreases in spleen weight, and concentrations of adrenal gland ascorbic acid and corticosterone. These effects were attenuated by ST (50 and 100 mg/kg, p.o.) and PG (100 mg/kg, p.o.), administered once daily over a period of 14 days, the period of stress induction. Chronic stress also induced glucose intolerance, suppressed male sexual behaviour, induced behavioural depression (Porsolt's swim despair test and learned helplessness test) and cognitive dysfunction (attenuated retention of learning in active and passive avoidance tests), and immunosuppression (leucocyte migration inhibition and sheep RBC challenged increase in paw oedema in sensitized rats). All these chronic stress-induced perturbations were attenuated, dose-dependently by ST (50 and 100 mg/kg, p.o.) and PG (100 mg/kg, p.o.). Chronic stress-induced increase in rat brain tribulin activity was also reversed by these doses of ST and by PG. The results indicate that ST has significant adaptogenic activity, qualitatively comparable to PG, against a variety of behavioural, biochemical and physiological perturbations induced by unpredictable stress, which has been proposed to be a better indicator of clinical stress than acute stress parameters. The likely contribution of the individual constituents of ST in the observed adaptogenic action of the polyherbal formulation, have been discussed.
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Evans EGV, Bulmer GS, Aly R, Coo-Barcelona L, Chakrabarti A, M. R. I. de Elias-Costa, Gugnani HC. Training medical mycologists in developing countries. Med Mycol 2000. [DOI: 10.1080/mmy.38.1.33.40] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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Kansal DK, Chakrabarti A. An observational study on neurobehavioural effects of acute oxydemeton-methyl (insecticide and acaricide) exposure in rats. INDIAN JOURNAL OF PHYSIOLOGY AND PHARMACOLOGY 2000; 44:57-63. [PMID: 10919096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Oxydemeton-methyl, an organophosphate insecticide and acaricide produced decrease in the exploratory behaviour and prolongation of barbitone sodium-induced hypnosis after intermittent aerosol spray inhalational exposure for 1 h in rats compared to the saline control group. Further, CD50 +/- S.E.M. value for pentylenetetrazole (PTZ) and CI50 +/- S.E.M. value for electroshock (i.e. the dose of PTZ and intensity of electroshock producing positive seizure response in 50% of rats) were significantly decreased by acute exposure to oxydemeton-methyl compared to that of saline control group. The study has established the central nervous system depressant effect and proconvulsant potential of oxydemeton-methyl which is widely used by the agricultural workers in the form of field spray.
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Schatten H, Ripple M, Balczon R, Weindruch R, Chakrabarti A, Taylor M, Hueser CN. Androgen and taxol cause cell type-specific alterations of centrosome and DNA organization in androgen-responsive LNCaP and androgen-independent DU145 prostate cancer cells. J Cell Biochem 2000; 76:463-77. [PMID: 10649443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
We investigated the effects of androgen and taxol on the androgen-responsive LNCaP and androgen-independent DU145 prostate cancer cell lines. Cells were treated for 48 and 72 h with 0.05-1 nM of the synthetic androgen R1881 and with 100 nM taxol. Treatment of LNCaP cells with 0.05 nM R1881 led to increased cell proliferation, whereas treatment with 1 nM R1881 resulted in inhibited cell division, DNA cycle arrest, and altered centrosome organization. After treatment with 1 nM R1881, chromatin became clustered, nuclear envelopes convoluted, and mitochondria accumulated around the nucleus. Immunofluorescence microscopy with antibodies to centrosomes showed altered centrosome structure. Although centrosomes were closely associated with the nucleus in untreated cells, they dispersed into the cytoplasm after treatment with 1 nM R1881. Microtubules were only faintly detected in 1 nM R1881-treated LNCaP cells. The effects of taxol included microtubule bundling and altered mitochondria morphology, but not DNA organization. As expected, the androgen-independent prostate cancer cell line DU145 was not affected by R1881. Treatment with taxol resulted in bundling of microtubules in both cell lines. Additional taxol effects were seen in DU145 cells with micronucleation of DNA, an indication of apoptosis. Simultaneous treatment with R1881 and taxol had no additional effects on LNCaP or DU145 cells. These results suggest that LNCaP and DU145 prostate cancer cells show differences not only in androgen responsiveness but in sensitivity to taxol as well.
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Evans EGV, Bulmer GS, Aly R, Coo-Barcelona L, Chakrabarti A, Elias-Costa MRID, Gugnani HC. Training medical mycologists in developing countries. Med Mycol 2000. [DOI: 10.1080/mmy.38.s1.33.40] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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Liu H, Chakrabarti A. Molecular dynamics study of adsorption and spreading of a polymer chain onto a flat surface. POLYMER 1999. [DOI: 10.1016/s0032-3861(99)00081-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Jha V, Sakhuja V, Gupta D, Krishna VS, Chakrabarti A, Joshi K, Sud K, Kohli HS, Gupta KL. Successful management of pulmonary tuberculosis in renal allograft recipients in a single center. Kidney Int 1999; 56:1944-50. [PMID: 10571806 DOI: 10.1046/j.1523-1755.1999.00746.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Pulmonary infections, especially tuberculosis, are responsible for significant mortality and morbidity among renal transplant recipients in developing countries. Conventional diagnostic modalities are associated with a low yield, delaying specific therapy. METHODS All patients transplanted within a 1.5-year period were prospectively followed-up for one year. Patients were on a cyclosporine-based triple immunosuppressive regimen. None received isoniazid prophylaxis, and those transplanted in the last seven months of the study period received daily cotrimoxazole. Patients exhibiting unequivocal evidence of pulmonary infections underwent further evaluation. Search for offending organisms was made by sputum examination and bronchoalveolar lavage (BAL). RESULTS . Thirty-nine infection episodes were recorded in 34 patients. M. tuberculosis was isolated during 10 episodes, pyogenic bacteria and Pneumocystis carinii in 6 each, candida in 4, aspergillus in 3, cytomegalovirus (CMV) in 3, and nocardia and mucor in one episode each. More than one organism was isolated during five episodes. Bacterial pneumonia and tuberculosis were diagnosed in another seven and two patients, respectively, on the basis of a therapeutic response to specific chemotherapy. Over two thirds of the organisms were identified by examination of BAL fluid. BAL was useful in the diagnosis of tuberculosis and P. carinii pneumonia but was relatively insensitive for CMV and bacterial infections. An increased frequency of acute rejection and higher serum creatinine were factors that predisposed to infections. All patients with pulmonary tuberculosis made a full recovery. CONCLUSIONS Tuberculosis and P. carinii are the most common nonpyogenic infections in the first year after transplantation in developing countries. An aggressive search for tubercle bacilli should be made using bronchoscopy and examination of BAL fluid in patients not responding to a short trial of antibiotics. A four-drug regime without rifampicin given for 18 months is effective for pulmonary tuberculosis in patients on cyclosporine. We recommend routine prophylactic use of one single-strength tablet of cotrimoxazole daily for at least six months after transplantation.
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Singh K, Chakrabarti A, Narang A, Gopalan S. Yeast colonisation & fungaemia in preterm neonates in a tertiary care centre. Indian J Med Res 1999; 110:169-73. [PMID: 10680302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023] Open
Abstract
Seventy consecutive preterm neonates who stayed in the hospital for more than seven days between March and October 1996, were studied for colonisation at oral, umbilical, groin, and rectal areas and for fungaemia. Overall, 71.4 per cent of the neonates were colonised and colonisation occurred within 24 h in 38 per cent preterm neonates. Neonates weighing less than 1500 g were colonised more frequently at more than one site and had higher load of yeast. Candida albicans (19%), Pichia (Hansenula) anomala (17.5%), C. tropicalis (13.2%), C. parapsilosis (12.3%) and Trichosporon cutaneum (10.0%) were the predominant colonising yeasts. Fungaemia was detected in 22.8 per cent of preterm neonates with predominance of P. anomala fungaemia (62.5%). Prematurity, male sex, broad spectrum antibiotic therapy, intubation and higher colonising rate were identified as significant risk factors for development of fungaemia. Except one strain of C. tropicalis, all yeast strains were sensitive to commonly used systemic antifungal agents. Study highlights the importance of routine surveillance of yeast colonisation of preterm neonates with identifying possible risk factors.
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Chakrabarti A, Srivastava S, Swaminathan CP, Surolia A, Varadarajan R. Thermodynamics of replacing an alpha-helical Pro residue in the P40S mutant of Escherichia coli thioredoxin. Protein Sci 1999; 8:2455-9. [PMID: 10595549 PMCID: PMC2144191 DOI: 10.1110/ps.8.11.2455] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Escherichia coli thioredoxin is a 108 amino acid oxidoreductase and contains a single Met residue at position 37. The protein contains a long alpha-helical stretch between residues 32 and 49. The central residue of this helix, Pro40, has been replaced by Ser. The stabilities of the oxidized states of two proteins, the single mutant M37L and the double mutant M37L,P40S, have been characterized by differential scanning calorimetry (DSC) and also by a series of isothermal guanidine hydrochloride (GuHCl) melts in the temperature range of 277 to 333 K. The P40S mutation was found to stabilize the protein at all temperatures upto 340 K though both proteins had similar Tm values of about 356 K. At 298 K, the M37L,P40S mutant was found to be more stable than M37L by 1.5 kcal/mol. A combined analysis of GuHCl and calorimetric data was carried out to determine the enthalpy, entropy, and heat capacity change upon unfolding. At 298 K there was a large, stabilizing enthalpic effect in P40S though significant enthalpy-entropy compensation was observed and the two proteins had similar values of deltaCp. Thus, replacement of a Pro in the interior of an alpha helix can have substantial effects on protein stability.
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Schatten H, Chakrabarti A, Levine HG, Anderson K. Utilization of the aquatic research facility and fertilization syringe unit to study sea urchin development in space. JOURNAL OF GRAVITATIONAL PHYSIOLOGY : A JOURNAL OF THE INTERNATIONAL SOCIETY FOR GRAVITATIONAL PHYSIOLOGY 1999; 6:43-53. [PMID: 11543085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
Methods were developed for the investigation of the effects of microgravity on early development in sea urchins within the Canadian Space Agency's Aquatic Research Facility (ARF). The ARF payload provided light, temperature control, automated fixation capability, and a 1 G on-orbit centrifuge control. Eggs and embryos of either the sea urchin species Lytechinus pictus or Strongylocentrotus purpuratus were loaded into Standard Container Assemblies (SCAs) which comprised the experimental aquaria (33 mL volume) contained within the ARF. A newly developed Fertilization Syringe Unit (FSU) was used to achieve "in-flight" fertilization capability. Fixative solutions were preloaded into fixation blocks maintained adjacent to the SCAs and injected at pre-selected time points, resulting in final (diluted) concentrations of either 0.5% or 2% glutaraldehyde (depending upon embryonic stage). Light, scanning, and transmission electron microscopy determined that all desired embryonic and cell division stages (16-cell stage, blastula, gastrula, and pluteus) were preserved using the experimental protocols and fixation capability provided by the ARF/FSU system.
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Abstract
The discovery of endocannabinoids such as anandamide and the wide spread localization of cannabinoid receptors in the brain and peripheral tissues, suggests that the cannabinoid system represents a previously unrecognized ubiquitous net work in the nervous system, whose physiology and function is unfolding. In this study, we tested the hypothesis that some of the actions of anandamide are independent of a cannabinoid receptor mechanism. This was accomplished by the use of cannabinoid agonist and antagonist interaction in an in-vitro and in-vivo test systems. In-vitro, we used Xenopus laevis oocytes expression system and two-voltage clamp technique in combination with differential display polymerase chain reaction to determine whether the differential display of genes following treatment with anandamide may be linked to AMPA glutamate receptor. The differential expression of genes in vivo after the sub-acute administration of anandamide could not be directly linked with the AMPA glutamate receptor. In the voltage clamp studies we investigated the effects of anandamide on recombinant AMPA GluR3 subunit currents generated by kainic acid in oocytes expressing the AMPA glutamate receptor. In the in-vitro studies, we present evidence that anandamide inhibited the kainate activated currents in oocytes expressing AMPA glutamate receptor involves cAMP transduction via a cannabinoid receptor independent mechanism. In the in-vivo studies, SR141716A, the CB1 antagonist, induced anxiolysis, that was dependent on the mouse strain used in the anxiety model and blocked the anxiogenic effects of anandamide or methanandamide whereas SR141716A had no effect on the anandamide inhibition of kainate activated currents in-vitro.
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