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Biomedical subjects

B Ghosh

Publications and source records attributed to B Ghosh.

At least 19 recordsLinked to original sources
PubMed1998

Expression of abscisic acid-responsive element-binding protein in salt-tolerant indica rice (Oryza sativa L. cv. Pokkali).

As the products of abiotic stress and ABA inducible genes are predicted to play an important role in the mechanism of salt tolerance, the expression of transcription factor that recognizes abscisic acid-responsive element (ABRE) is likely to be regulated when plants are exposed to abiotic stress. Northern analysis of total RNA from control and salt-treated 10-day-old Pokkali (salt tolerant) rice plants was performed to find out the level of transcripts homologous to wheat cDNA (GC19) for EmBP-1 (bZIP class factor), a transcription factor that recognizes ABRE. Salinity stress (72 h)-induced accumulation of two transcripts, of 2.0 kb (r2.0) and 1.5 kb (r1.5), in roots was detected. Both transcripts were detectable even after 6 h of salt or abscisic acid treatment, whereas sheath and lamina showed constitutive levels of r1.5 transcript. When 32P-labeled DNA containing ABRE was used in a gel mobility shift assay, a low level of complex formation by binding factor was detected from the nuclear extract of lamina of control rice plants. Quantitative enhancement of complex formation was found with the nuclear extract prepared from the lamina of plants treated with 200 mM NaCl for 26 h over control nuclear extract, suggesting a step of regulation of expression of ABRE-binding protein in response to salinity stress. South-western blot analysis of equal amounts of nuclear proteins of lamina showed binding of 32P-labeled ABRE-DNA with two polypeptides (22-28 kDa) present at constitutive levels in control or NaCl-treated plants. Preincubation of the laminar nuclear extract of control plants, with spermidine or proline at 5 mM concentration showed quantitative enhancement of ABRE binding activity. Kinetics of spermidine stimulation showed gradual increase of complex formation from 5 mM concentration. Similarly, addition of GTP to the control nuclear extract also showed quantitative enhancement of complex formation and heparin was found to inhibit GTP activated complex formation by about 25%. Results may suggest the presence of ABRE binding protein in presynthesized and inactive form in control plants and GTP mediated activation is probably one of the way to regulate the expression of ABRE-binding factor.

Abscisic Acid↗
PubMed1998

Improved taxol yield in cell suspension culture of Taxus wallichiana (Himalayan yew)

Cell culture of Taxus wallichiana Zucc (= T. baccata ssp wallichiana Zucc. Pilg.) (Himalayan yew) has been established and taxol-producing cell lines selected by cell line cloning. Cell line NC110 derived from needle leaf of a 40-year-old tree growing in Darjeeling Himalayas produced 0.018% taxol in B5 basal medium supplemented with 2,4-D (2 mg/l), kinetin (0.5 mg/l), and casein hydrolysate (0.5%). This cell line has been maintained for over 2 years. Significant enhancement in the level of taxol (0.05%) was obtained in this cell line by supplementation of the basal medium with 5 mg/l of IAA-phenylalanine instead of 2,4-D without adversely affecting cell growth. IAA-glycine also enhanced taxol level (0.03%) while IAA alone (1-10 mg/l) was ineffective in inducing taxol accumulation. Using three different cell lines with different taxol-producing capacities, it has been demonstrated that 2,4-D and IAA-phenylalanine when present alone favour growth and taxol production but when combined enhance biomass to a maximum (six-fold in NC110) without enhancing taxol accumulation, suggesting that a two-stage culture may be beneficial for optimising taxol accumulation in cell culture of T. wallichiana.

Antineoplastic Agents, Phytogenic↗
PubMed1998

Regulatory role of nucleus accumbens in the ingestion of sucrose and saccharine.

Adult albino rats of Wistar strain of 200 to 250 g body weight were lesioned at nucleus accumbens either in the shell area or in core area. The rats were offered 0.2% saccharine solution or 12% sucrose solution or water for drinking. During the prelesion period, rats consumed more of saccharine followed by sucrose and water. The lesion of core area increased the consumption of both the sweet taste solutions but did not affect the water intake. Lesioning of shell area caused an increase in water and sucrose intake whereas saccharine intake remained unaffected. The results suggest that the core area of nucleus accumbens subserves taste induced ingestion and the shell area mediates the effect of nutritional value of food.

Animals↗
PubMed1997

Epilenticular lens implantation versus extracapsular cataract extraction and lens implantation in children.

PURPOSE: To compare the results of epilenticular posterior chamber intraocular lens (IOL) implantation and pars plana lensectomy with those of extracapsular lens aspiration and posterior chamber IOL implantation in eyes with pediatric cataracts. SETTING: Guru Nanak Eye Centre, New Delhi, India. METHODS: Forty eyes with childhood cataract of varied etiology were divided into two groups of 20 eyes each, matched by age, sex, and type of cataract. Group A had epilenticular IOL implantation with pars plana lensectomy. Group B had extracapsular lens aspiration with posterior chamber IOL implantation. Follow-up ranged from 1 to 3 years. RESULTS: All 20 eyes in Group A maintained a clear pupillary axis from the immediate postoperative period to the last follow-up. In Group B, 80% of eyes developed varying degrees of posterior capsule opacification (PCO), which hampered vision. In Group A, 95% of eyes had a visual acuity of 6/12 or better; only 45% of eyes in Group B achieved a visual acuity of 6/60 or better. CONCLUSION: Although patients in both groups had good visual recovery, those having epilenticular IOL implantation with pars plana lensectomy maintained a clear pupillary axis and did not develop PCO, preventing the need for secondary intervention.

Cataract↗
PubMed1997

Expression of arginine decarboxylase in seedlings of indica rice (Oryza sativa L.) cultivars as affected by salinity stress.

The effect of salinity stress on the activity of arginine decarboxylase (ADC, EC 4.1.1.19), the first enzyme in biosynthesis of polyamines (PA) from arginine, as well as its transcript level has been compared in salt-sensitive (M-1-48) and salt-tolerant (Pokkali) rice cultivars. Treatment of 72 h grown seedlings either with increasing concentrations of NaCl or with 150 mM NaCl for different time periods, showed a gradual increase of activity in Pokkali. In M-1-48 an immediate increase followed by sharp decrease was observed on prolonged treatment beyond 6 h or above 150 mM NaCl. To generate a DNA probe for ADC, the polymerase chain reaction was used with oat genomic DNA and sequence-specific primers. A region of oat genomic DNA containing a coding sequence for 166 amino acids of the C-terminal part of the ADC enzyme was amplified and called OAD1. Southern analysis of EcoRI- or BamHI-cut genomic DNAs from different cultivars of rice with OAD1 as the probe revealed strong hybridization with one DNA fragment of rice and restriction fragment length polymorphism (RFLP) was noticed. Northern analysis of total RNA of rice with OAD1 as the probe revealed hybridization with a transcript of similar size to the ADC transcript in oat. While in Pokkali, at least a 20-fold accumulation of OAD1 homologous transcript was detected after treatment with 200 mM NaCl, only a seven-fold increase in transcript level was found in M-1-48 after 150 mM NaCl treatment. Results suggest that in the salt-tolerant rice cultivar Pokkali, ADC enzyme activity increases and its transcript also accumulates during the prolonged salinity stress, this mechanism is absent in the salt-sensitive rice cultivar M-1-48 where a prolonged period of salinity stress down-regulates both ADC activity and its transcript level.

Carboxy-Lyases↗
PubMed1996

Tissue differences in antioxidant enzyme gene expression in response to endotoxin.

The effect of endotoxin on antioxidant gene expression and antioxidant enzyme activity in homogenates of the heart, liver, and kidney from Sprague-Dawley rats was compared by quantitation of m-RNA and enzyme activities. Alterations in the message level for Cu-Zn superoxide dismutase (SOD), Mn SOD, and catalase varied with the tissue type, length of exposure to endotoxin, and dose of endotoxin. In general, endotoxin treatment reduced Cu-Zn SOD expression in the heart and liver, but had no noticeable effect in the kidney. Mn SOD message levels were increased in the heart and kidney but decreased in the liver. Catalase expression was reduced in the kidney and increased marginally in the heart and liver. With regard to enzyme activity, endotoxin treatment reduced Cu-Zn SOD activity in the heart, liver, and kidney. Mn SOD activity showed little change in the heart, but increased in the liver and, to a lesser extent, in the kidney. Catalase activity showed little change in the heart and kidney but was decreased at 12 h in the liver. The differing responses of tissues to the oxidant stress of endotoxin exposure should be considered when evaluating the effect of endotoxin on antioxidant enzymes.

Animals↗
PubMed1996

The conserved lymphokine element-0 in the IL5 promoter binds to a high mobility group-1 protein.

The conserved lymphokine elements-0 (CLE0) in the IL5 promoter is essential for the expression of IL-5. Here, we report the cloning and expression of a cDNA encoding a novel CLE0-binding protein, CLEBP-1 from a mouse Th2 clone, D10.G4.1. Interestingly, it was found that the CLEBP1 cDNA sequence was almost identical to the sequences of known high mobility group-1 (HMG1) cDNAs. When expressed as a recombinant fusion protein in Escherichia coli, CLEBP-1 was shown to bind to the IL5-CLE0 element in electrophoretic mobility-shift assays (EMSA) and southwestern blot analysis. The CLEBP-1 fusion protein cross-reacts with and-HMG-1/2 in Western blot analysis. It also binds to the CLE0 elements of IL4, GMCSF and GCSF genes. CLEBP-1 and closely related HMG-1 and HMG-2 proteins may play key roles in facilitating the expression of the lymphokine genes that contain CLE0 elements.

Animals↗
PubMed1996

Abnormality in translational regulation of catalase expression in disorders of peroxisomal biogenesis.

Peroxisomal disorders are a newly described group of inherited neurological diseases. In disorders of peroxisomal biogenesis, e.g., Zellweger syndrome, owing to the lack of peroxisomes, catalase, a peroxisomal enzyme, is found to be present in the cytoplasm instead. We observed higher catalase activity (7.59 +/- 0.41 mU/ mg of protein) in cultured skin fibroblasts from Zellweger patients than in control fibroblasts (4.45 +/- 0.29 mU/mg of protein). Moreover, we also found that the majority of the catalase in Zellweger cells was present in the inactive form. The specific activities following reactivation in Zellweger and control cells were 12.1 and 4.9 mU/mg of protein, respectively. To understand the molecular basis of higher levels of catalase in Zellweger than control cells, we examined the rate of synthesis and turnover of catalase and levels of catalase mRNA and protein levels in Zellweger cells as compared with control cells. The initial rates of synthesis of catalase in Zellweger (1.68 +/- 0.15 mU/mg of protein) and control (1.51 +/- 0.14 mU/mg of protein) cells were similar. The rates of turnover of catalase in Zellweger (t1/2 = 47 +/- 8 h) and control (t1/2 = 49 +/- 7 h) were also similar. Consistent with the enzyme activity, the levels of catalase protein were higher in Zellweger cells as compared with control cells. On the other hand, there was no difference in the level of catalase mRNA between control and Zellweger cells. Although the rate of synthesis in Zellweger and control cells was initially similar, it was down-regulated to a lower level at approximately 72 h of culture in control fibroblasts as compared with Zellweger cells, which continued to synthesize catalase at the same rate up to 5 days in culture. The presence of similar levels of mRNA in control and Zellweger cells and continued synthesis of catalase in Zellweger cells at a higher level as compared with control cells suggest a loss of regulation at the translational level.

Adrenoleukodystrophy↗
PubMed1996

Isolation of mammalian pol beta type DNA polymerase in shoot tips of germinated seedlings of IR-8 rice (Oryza sativa L.).

A single polypeptide of approx. 67 kDa mol.wt. with DNA polymerase activity has been chromatographically purified from shoot tips of 72 hr. grown germinated seedlings of rice (Oryza sativa.L.cv IR-8). An approx. 4800 fold enrichment of specific activity was measured by the incorporation of 3H-dTMP into trichloroacetic acid insoluble fraction, using activated calf thymus DNA as template-primer. The enzyme uses different types of DNA but not RNA as a template. The enzyme requires Mg+2, high KCl, and is highly sensitive to dideoxyribonucleoside triphosphate but is unaffected by aphidicolin, suggesting a plant counterpart of mammalian DNA polymerase beta. Replication of M13mp18 single stranded DNA by extension of 5'32P-labeled 17-mer primer(-40) showed distributive type of DNA synthesis by the rice DNA polymerase beta, which is a characteristic feature of mammalian DNA polymerase beta.

DNA Polymerase I↗
PubMed1996

An unusual intraocular foreign body.

Retained intraocular cilia embedded in the retina are extremely rare. A report of an unusual case of cilia embedded in posterior retina is presented along with a review of available literature. A 22-year-old male presented with a history of diminished vision and metamorphopsia 1 month after the successful repair of an ocular perforation. Anterior segment examination revealed a sutured superotemporal limbal tear with a surgical iris coloboma and a normally positioned clear lens. Ophthalmoscopic examination revealed a normal optic disc, macular striations and 2 cilia embedded in the retina approximately 2 disc diameters superotemporal to fovea. Vitrectomy with removal of cilia and endolaser was performed. This unusual case shows that cilia may become embedded intraocularly during an ocular perforation and that transvitreal removal may be a preferred mode of therapy with the availability of sophisticated vitreoretinal instrumentation.

Adult↗
PubMed1995

Molecular cloning and sequencing of human palmitoyl-CoA ligase and its tissue specific expression.

A complimentary DNA clone encoding the entire human palmitoyl-CoA ligase has been isolated from a liver cDNA library and sequenced in it's entirety. The predicted product is a 699 amino acid protein. Southern analysis utilizing the human palmitoyl-CoA ligase gene as a probe revealed varying degrees of similarity amongst various mammalian species. The palmitoyl-CoA ligase gene is highly expressed in liver, heart, skeletal muscle and kidney, and to a lesser extent in brain, lung, placenta and pancreas. The expression of palmitoyl-CoA ligase in various tissue parallels the function of this enzyme in the metabolism of fatty acids in these tissues.

Amino Acid Sequence↗
PubMed1995

Role of beta-carotene on the changes in activity patterns and levels of biotransforming enzymes in transplantable murine lymphoma.

The differential levels of induction of hepatic microsomal cytochrome P-450 (cyt. P-450), UDP-glucuronyl transferase (UDPGT) and cytosolic glutathione-S-transferase (GST) activities were evaluated over various periods of time, following tumor transplantation in male Swiss albino mice in the presence and absence of beta-carotene supplementation in their basal diet (100 mg/kg). An increase in the total hepatic microsomal cytochrome P-450 and UDP-glucuronyl transferase and cytosolic GSH-transferase activities (1.5 to 2 fold) occurred during the later stage of tumor progression (22 +/- 2 days onwards). However, beta-carotene supplementation throughout the study increased or decreased the random activity trends of the above markers significantly (P < 0.05- < 0.01). Finally, beta-carotene supplementation could enhance the survival of the host bearing lymphoma by almost 2-fold (50-60 days) over and above the lymphoma controls (30-35 days).

Animals↗
PubMed1995

Physiological potential of beta-carotene in prolonging the survival of the host bearing transplantable murine lymphoma.

beta-Carotene, when supplemented in diet, has been found to increase the survival period of mice bearing a transplantable tumor, Dalton's lymphoma. Tumor cell-count, body weight pattern, hematological parameters like total count showed marked alterations in a dose-responsive manner with beta-carotene administration when compared to their untreated counterparts. Decreased tumor cell proliferation is also reflected by increased hemoglobin levels of the host.

Animals↗