PubMed Health⌕ Search

Biomedical subjects

Debabrata Ghosh

Publications and source records attributed to Debabrata Ghosh.

12 recordsLinked to original sources
PubMed2006

Long-term exposure to arsenic affects head kidney and impairs humoral immune responses of Clarias batrachus.

The present study was aimed at determining the effects of long-term arsenic exposure on the head kidney (HK) and ensuing humoral immune responses in Clarias batrachus L. Long-term exposure (150 days) to non-lethal concentrations of arsenic (42.42 microM) resulted in significant time-dependent alterations in HK cell number eventually affecting the HK somatic index. Prolonged exposure to arsenic also suppressed HK-B cell proliferation and led to significant reduction in serum immunoglobulin levels and antigen-specific serum bacterial agglutinin titers. A decline in the number of antigen-specific plaque-forming cells with duration of arsenic exposure was noted in the HK. Enzyme linked immunosorbent assays further revealed that arsenic exposure inhibited the release of "IL-4 like factors" from HK-T cells. Histological studies documented time-dependent changes in the structure and cellular composition of HK characterized by extensive lymphocytopenia, decrease in melano-macrophage population and hemosiderin accumulation. From exposure-challenge studies with Aeromonas hydrophila it was evident that pathogens could efficiently disseminate and colonize distant host tissues in the exposed fish. Moreover, the ability to decrease the pathogen load was also significantly reduced in the arsenic-exposed fish. Thus long-term exposure to non-lethal concentrations of arsenic affects HK and interferes with the humoral immune system of C. batrachus rendering them immunocompromised and susceptible to pathogenic challenge.

Aeromonas hydrophila↗
PubMed2006

An attenuated plasmid-cured strain of Aeromonas hydrophila elicits protective immunity in Clarias batrachus L.

Wild type Aeromonas hydrophila (Strain AO1) isolated from the lesions of ulcerative disease syndrome (UDS) affected fish bears a 21 kb virulence plasmid. With plasmid curing the isolates became attenuated and failed to induce fatal haemorrhagic ulcers in fish. The objective of the present work was to check the immunogenicity of these plasmid-cured derivatives and determine whether such strains could be used as candidate antigens for eliciting protective immunity to A. hydrophila infections in the Indian catfish Clarias batrachus L. It was observed that the plasmid-cured strains were immunogenic since infection with live plasmid-cured AO1 isolates generated effective T cell responses and led to increase in serum antibacterial agglutinin titres in C. batrachus. Plasmid-cured AO1 strains injected into C. batrachus could disseminate into head kidney (HK) and spleen but never attained the same bacterial loads obtained with wild type AO1 and were cleared rapidly from the host. Immunisation with plasmid-cured bacteria prevented systemic spread and conferred protection against lethal challenge (10 x LD(50)) with wild type A. hydrophila as well as other pathogenic strains of Aeromonas sp. These results demonstrate the potentials of plasmid-cured A. hydrophila derivatives as candidate antigens for eliciting protective immunity in fish and the possibility of using such isolates as shuttle vectors in aquaculture.

Aeromonas hydrophila↗
PubMed2006

Monoclonal anti-leukemia inhibitory factor antibody inhibits blastocyst implantation in the rhesus monkey.

INTRODUCTION: Leukemia inhibitory factor (LIF) appears important in the process of blastocyst implantation in primates. In the present study, we investigated the effect on pregnancy outcome of the administration of a monoclonal antibody (mAb) to recombinant human (rh) LIF (anti-LIF mAb) into the uterine cavity of mated female rhesus monkeys during the peri-implantation period. METHODS: Two milligrams of either mouse mAb to rhLIF or isotype-matched immunoglobulin (Ig) was administered into the uterine cavity on estimated Day 5 or Day 8 after ovulation either through the vagina (n=33) or through the oviduct (n=29) of successfully mated females. RESULTS: There was a significant (p<.04) decline in pregnancy outcome in groups treated with anti-LIF mAb (8 pregnancies from 32 animals) compared with control animals (24 pregnancies from 30 animals). There was, however, no significant difference in pregnancy inhibition between a group of animals subjected to vaginal route treatment and a group of animals subjected to oviductal route treatment, as well as between a group subjected to anti-LIF mAb on Day 5 after ovulation and a group subjected to anti-LIF mAb on Day 8 after ovulation. No significant change was seen in the number of viable pregnancy in animals treated with 6 mg of anti-LIF mAb (5 pregnancies from 16 animals) compared with animals treated with 2 mg of anti-LIF mAb (8 pregnancies from 32 animals). Serum profiles of estradiol, progesterone, monkey chorionic gonadotropin and mouse IgG did not show any difference among different treatment subgroups during the luteal phase. However, among animals treated with anti-LIF mAb, the mean area under the curve for serum mouse IgG in pregnant animals (234+/-55 microg/mL day) was significantly (p<.01) less than that of nonpregnant animals (1325+/-97 microg/mL day). CONCLUSION: The results of the present study put forward the proof of concept that LIF plays a critical role in the process of blastocyst implantation in the rhesus monkey.

Animals↗
PubMed2006

Prednisolone in Duchenne muscular dystrophy with imminent loss of ambulation.

An open controlled trial of 0.75 mg/Kg/day prednisolone was conducted at a stage when the patients had started falling several times in a day and stopped on their attaining a chair bound stage, thus minimising the total period of steroid therapy. Out of the 67 DMD patients enrolled in this study, 44 were put on prednisolone therapy and 23 served as controls. All patients were followed-up at two-monthly intervals for two years and thereafter they continued to take their respective medications till their chair-bound stage; then the drug was gradually withdrawn. In the treatment group 24 patients could not continue the trial because of adverse effects - 14 due to excessive obesity, 3 due to measles, 4 due to pulmonary tuberculosis, 2 due to recurrent throat and chest infection and 1 due to an unexplained high leukocyte count. Of the remaining 20 patients in the treatment group, steroid therapy was stopped in 5 patients as there was no improvement in power in six months. Fifteen patients in the treatment group and 19 patients in the control group could be followed regularly for 2 years and then up to chair-bound stage. Outcome parameters included fall frequency, peak expiratory flow rate, limb muscle power, ability to lift weights, time taken in getting up from squatting position, walking 9 metres and climbing 13 stairs. Maximum improvement was noted between 2 and 4 months while mild improvement in some parameters continued up to six months. All parameters remained stabilised for 1 year or so, after which there was slight deterioration. Deterioration at 2 years was, however, less than the natural course of events noted in control patients. Prednisolone treated patients and controls became chair bound at the mean age of 169 +/- 9 and 132 +/- 8 months respectively. Till the ideal stage of the disease and the type or dosage of starting steroid therapy is defined by specially designed studies, 0.75 mg/Kg/day prednisolone therapy may be started in DMD patients at the stage of frequent falls ( > 10 / day) on walking or increased get-up time ( > 10 s) as observed while testing Gowers' sign; this improves muscle power and timing of motor performance within 2-4 months of onset of therapy in about 75% of those who tolerate this therapy, with a possible gain of approximately 3 years in terms of independent walking.

Accidental Falls↗
PubMed2006

Perturbations in the catfish immune responses by arsenic: organ and cell specific effects.

The present study was an attempt to elucidate the effect of non-lethal arsenic (As) exposure (1/10 LC50) on different immunologically important organs and cells of a catfish. Clarias batrachus L. were exposed to arsenic trioxide for different time intervals, which resulted in significant, time-dependent changes in total head kidney and splenic leucocyte count (p<0.05) and reduction in the organosomatic indices (p<0.05) of these two important immunocompetent organs. Routine histological studies revealed arsenic induced changes in the cellular composition of head kidney and spleen. Arsenic also induced time-dependent and tissue-specific alterations in T and B cell functioning in catfish. When checked for its effects on macrophages, it was noted that arsenic interfered with bacterial phagocytosis. Furthermore, arsenic affected the general immune status of C. batrachus and rendered the fish immunocompromised and susceptible to pathogens.

Aeromonas hydrophila↗
PubMed2005

Target-oriented anti-implantation approaches for pregnancy interception: experiences in the rhesus monkey model.

Blastocyst implantation is a critical process in the establishment of pregnancy in eutherian mammals and requires a harmonious symbiosis between the developing conceptus and the differentiating maternal uterus. A better understanding of this symbiotic relationship will provide novel approaches and interventions for realizing anti-implantation strategies for effective fertility regulation and reproductive health care management. We have been using the rhesus monkey (Macaca mulatta) as a nonhuman primate model to this end. In the present study, the process of progesterone-mediated regulation of endometrial receptivity for blastocyst implantation has been targeted by the use of mifepristone as an emergency contraceptive agent. Furthermore, based on cell-specific, temporal and spatial distribution of vasotropic cytokines and mediators in the "receptive" and periimplantation periods, the pregnancy interceptive potentials of (a) monoclonal antibody (MAb) to leukemia inhibitory factor (LIF); (b) inhibitors of nitric oxide synthase [e.g., N6-nitro-l-arginine (l-NAME) and aminoguanidine]; and (c) MAb to vascular endothelial growth factor (VEGF) were examined. LIF is a progesterone-responsive pleiotropic cytokine that functions as a proinflammatory cytokine, together with interleukins 1 and 6, during the process of implantation-placentation in primates, and its immunoneutralization with MAb resulted in inhibition (p<.04) of pregnancy establishment in the rhesus monkey. However, timed administration of l-NAME or aminoguanidine failed to inhibit blastocyst implantation in a significant manner. Also, no synergistic antinidatory action of antiprogestin combined with l-NAME was detected in the rhesus monkey. The application of MAb to VEGF during the periimplantation period, on the other hand, led to significant (p<.04) prevention of pregnancy without influencing steroid hormone levels in the circulation. Our data lend support to the hypothesis that VEGF is essential for pregnancy establishment and that trophoblast-derived VEGF, acting via its specific receptors Flt-1 and KDR, is necessary for blastocyst implantation. The use of cDNA-based expression arrays followed by differential display analysis has provided preliminary understanding of the nature of gene cluster networks operative in the receptive endometrium of potential conception cycles in the rhesus monkey. This knowledge may, in the future, lead to further innovative anti-implantation strategies for targeted pregnancy interception.

Animals↗
PubMed2003

Experimental models for human implantation.

An understanding of the cellular and molecular basis of blastocyst implantation in the human remains as yet a black box, however, a few experimental models using human and non-human primate species have addressed this issue. This review attempts to highlight, based on experimental evidence, the paradigm shifts in our understanding of the endocrine basis of embryo implantation, and the nature of dialogue between a growing, viable conceptus and maternal endometrial cells in the establishment of 'receptivity' for blastocyst implantation. It is being proposed that an existing inflammation paradigm of blastocyst implantation could be tested using an experimental model to compare tissue behaviour of conceptus associated endometrial cells with that occurring after induction of deciduoma in hormone-primed uterus. We anticipate that an in vitro model of blastocyst implantation using the experimental models of homotypic and heterotypic cultures of uterine epithelial and stromal fibroblast cells expressing structural and functional phenotypic responses as observed in situ may provide us with necessary clues about the temporal and spatial nature of cellular and molecular functions involving various endocrine and paracrine factors at implantation.

Animals↗
PubMed2002

Activation of early signaling transcription factor, NF-kappaB following low-level manganese exposure.

Occupational and environmental exposure to manganese (Mn(2+)) is an increasing problem. It manifests neuronal degeneration characterized by dyskinesia resembling Parkinson's disease. The study was performed to test the hypotheses whether exposure to Mn(2+) alters cellular physiology and promotes intracellular signaling mechanism in dopaminergic neuronal cell line. Since transcription factors have been shown to play an essential role in the control of cellular proliferation and survival, catecholaminergic rich pheochromocytoma (PC12) cells were used to measure changes in the DNA binding activities of nuclear factor kappa B (NF-kappaB) by electrophoretic mobility shift assay (EMSA) following Mn(2+) (0.1-10 microM) exposure. Cells that were exposed to Mn(2+) produced five-fold-activation of transcription factor NF-kappaB DNA binding activity. This remarkable increase was seen within 30-60 min period of Mn(2+) exposure. Activation of NF-kappaB DNA binding activity by Mn(2+) at 1.0 microM correlated with proteolytic degradation of the inhibitory subunit IkappaB(alpha) as evidenced in cytosol. Additional experiments on NF-kappaB reporter gene assay also showed increased NF-kappaB gene expression at 1.0 and 5.0 microM Mn(2+) and this was completely blocked in the presence of NF-kappaB translocation inhibitor, IkappaB(alpha)-DN supporting that NF-kappaB induction occurred during Mn(2+) exposure. In addition, Mn(2+) exposure to PC 12 cells led to activation of signal responsive mitogen activated protein kinase kinase (MAPKK). These results suggest that Mn(2+) at a low dose appears to induce the expression of immediate early gene, NF-kappaB through MAPKK by a mechanism in which IkappaB(alpha) phosphorylation may be involved.

Animals↗
PubMedDate not supplied

Immunohistological localization of insulin-like growth factor binding protein-1 in primary implantation sites and trauma-induced deciduomal tissues of the rhesus monkey.

We have earlier demonstrated that there is a close similarity in the temporo-spatial pattern in the onset of oedema, epithelial-plaque transformation, stromal decidualization and influx of granulated lymphocytes in artificially trauma-induced deciduomal endometrium with such events in maternal endometrium at the primary implantation site during early stages of pregnancy in the rhesus monkey. In the present study, we have immunohistochemically examined whether the pattern of insulin-like growth factor-binding protein 1 (IGFBP-1) protein expression in conceptus tissue and maternal endometrium during lacunae and villous placenta stages of gestation in the rhesus monkey is developmental stage-specific and whether a discernible difference exists in the temporo-spatial characteristics of IGFBP-1 protein expression between conceptus associated implantation-decidualization and trauma induced deciduoma in the rhesus monkey. Trophoblast cells failed to exhibit IGFBP-1 immunopositive staining at any stage of implantation-placentation studied. Epithelial cells in plaque acini, endothelial cells, and vascular smooth muscle also did not show any immunopositive staining for IGFBP-1 in samples of primary implantation sites and trauma-induced deciduoma. Maternal endometrial epithelial and stromal-decidual cells however exhibited a temporal and spatial pattern of IGFBP-1 expression in cell-type specific manner and clear distinctions were observed between conception and deciduoma samples. Our results suggest that IGFBP-1 expression is highly tissue and development-specific and that conceptus-derived signals are necessary to initiate the glandular expression of IGFBP-1 during the early stage of gestation.

Animals↗