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C Ghosh

Publications and source records attributed to C Ghosh.

At least 19 recordsLinked to original sources
PubMed2001

Validity of the quasiharmonic analysis for surface thermal expansion of Ag(111).

For temperatures above 0.6T(m) (the bulk melting temperature) we show that the quasiharmonic approximation leads to increasingly larger values of the surface thermal expansion of Ag(111) as compared to that obtained from molecular dynamics simulations based on fully anharmonic interaction potentials. The inadequacy of the quasiharmonic approximation is traced to the excessive softening of the surface phonon frequencies. We discuss the validity of the quasiharmonic approximation for surfaces at elevated temperature, in view of recent x-ray scattering data on Ag(111).

Journal Article↗
PubMed2000

Efficient DNA transfection in neuronal and astrocytic cell lines.

We have studied different parameters for efficient DNA transfection in various cell types and with different size of the promoter. Here we report that the optimum condition for DNA transfection by electroporation is 350 V/960 microF for PC12, 450V/960 microF C6 cells, and 250 V/500 microF for COS-1 cells. For the human neuroblastoma (SK-N-SH) cells the optimum condition for DNA transfection is by the calcium phosphate method. In promoter mapping studies, a serial deletion approach is commonly used. To optimize transfection we have selected three DNA constructs that varied in size from 4.5 to 12.4 kilobases (kb). We measured the promoter activity of these constructs under conditions of 'equal amount', 'equimolar', and 'equimolar plus carrier DNA to make it equal amount'. We recommend that for comparative purpose, transfection should be carried out under 'equimolar condition' without a need to adjust the total amount of DNA by carrier DNA. Taken together, our results suggest that efficient methods for DNA transfection are important to study gene regulation by devising better ways to deliver DNA into the mammalian cells.

Amyloid beta-Protein Precursor↗
PubMed2000

Editorial comment

Explore the source record for details and available documents.

Journal Article↗
PubMed2000

Intracellular delivery strategies for antisense phosphorodiamidate morpholino oligomers.

Antisense oligonucleotides inhibit gene expression by interfering with transcription, translation, or splicing. They show great potential as gene-specific, nontoxic therapy for a wide variety of diseases. They are also powerful tools to study gene function as well as for validation of therapeutic targets. Even with compelling evidence of activity in vivo, the majority of cell types in culture require technologies capable of efficiently delivering antisense oligonucleotides into the cytosolic/nuclear compartment of the cells in culture. Phosphorodiamidate morpholino oligomers (PMO) are a new generation of antisense oligomers with high specificity and efficacy. They inhibit translation of targeted mRNA by steric blockade. Different methods were evaluated for efficient delivery of PMO into the cells in culture. Efficacy was compared using the PMO targeted to the 5'-untranslated region (5'-UTR) of alpha-globin-luciferase reporter fusion gene mRNA. A functional assay based on the lunciferase reporter system was used to measure efficacy. The fluorescence-activated cell sorting (FACS) method was used for quantitative determination of PMO uptake into the cells. Physical methods, such as scrape-loading, syringe-loading, and osmotic-loading, provided efficient transfer of PMO into the cells, which resulted in higher efficacy. These procedures caused minimal damage to the cells. Cell permeabilization with streptolysin O did not improve the cell uptake of PMO. Complexation with cationic lipids, Lipofectin and Lipofectamine (GIBCO-BRL, Gaithersburg, MD) also failed to enhance the uptake of PMO. We conclude that physical methods are optimal for the delivery of neutrally charged PMO into cells in culture. Further, these methods do not leave residual material that may interfere with the interpretation of targeted gene function.

Bacterial Proteins↗
PubMed2000

Phase II evaluation of continuous-infusion 5-fluorouracil, leucovorin, mitomycin-C, and oral dipyridamole in advanced measurable pancreatic cancer: a North Central Cancer Treatment Group Trial.

At present there remains a need for more effective systemic therapy in advanced pancreatic cancer. Some studies have suggested that infusional chemotherapy schedules and biomodulation of 5-fluorouracil (5-FU) may improve the therapeutic outcome in advanced colon cancer. One such regimen that uses continuous infusion 5-FU, weekly leucovorin, daily dipyridamole, and intermittent mitomycin-C has activity in both colon and unresectable pancreatic carcinoma. The intent of this trial was to test the effectiveness of this four-drug regimen in advanced pancreatic cancer. Patients received 5-FU 200 mg/m2 daily by continuous infusion, leucovorin 30 mg/m2 IV weekly, mitomycin-C 10 mg/m2 day 1, and dipyridamole 75 mg orally four times daily for 5 weeks. After a 1-week break, treatment cycles were repeated every 6 weeks. Eligibility included biopsy-proven advanced measurable pancreatic cancer, Eastern Cooperative Oncology Group performance status 0 and 2, and no prior systemic chemotherapy. Of 46 evaluable patients, 9 partial responses and 1 complete tumor response were seen, for an overall response rate of 22% (95% confidence interval 11-36%). The median survival in the group of 50 patients registered to this trial was 4.6 months, with a range of 0.33 to 40.2 months. Toxicity was manageable, with the most common toxicities (> or =grade III National Cancer Institute Common Toxicity Criteria) being anorexia (13%), stomatitis (17%), and hand-foot syndrome (13%). Of note, little severe hematologic toxicity and no significant headaches were reported. Although some patients did respond, the therapeutic results are not encouraging enough to take this regimen to phase III testing.

Adult↗
PubMed2000

Photoactivation of vascular iNOS and elevation of cGMP in vivo: possible mechanism for photovasorelaxation and inhibition of restenosis in an atherosclerotic rabbit models.

Recently, intravascular low-power red laser light (LPRLL) therapy has been proposed for the prevention of postangioplasty restenosis due to the observed inhibition of experimental neointimal formation. The objective of this study was to determine the impact of endoluminal LPRLL on vascular levels of inducible nitric oxide synthase (iNOS) and cyclic guanosine monophosphate (cGMP) to help define the mechanism of this effect. Eight atherosclerotic male adult New Zealand White rabbits weighing 4-6 kg were used in these studies. The iliac arteries were treated in separate zones with: (1) balloon inflation only; (2) laser illumination only; and (3) balloon inflation + laser illumination. An uninjured zone of the iliac artery served as a control. Laser irradiation (630 nm) was delivered to the vessel wall via a Cold laser Illuminator (Cook, Inc., Bloomington, IN), with a 3 mm-diameter balloon. Experiments demonstrated that vascular cGMP levels obtained immediately following treatment in the balloon only group was the lowest (0.29 +/- 0.05 pmol/mg protein) and significantly lower compared with the uninjured controls (1.01 +/- 0.07 pmol/ mg protein) (P < 0.001). In the laser only treated group cGMP levels were significantly increased (2.87 +/- 0.12 pmol/mg protein) compared with the uninjured control (P < 0.001) and the balloon only group (P < 0.001). Vascular cGMP levels in the balloon + laser group (2.09 +/0.07 pmol/mg protein) was also increased compared to the balloon only (P < 0.001) and control (P < 0.001) groups. Qualitative analysis of Western blot demonstrated that laser illumination induces iNOS. In contrast balloon dilatation did not induce iNOS. Balloon + laser treatment, however, tended to restore the expression of iNOS. Our study demonstrated that intravascular low dose laser irradiation induces iNOS and elevates vascular cGMP in an in vivo atherosclerotic rabbit model.

Angioplasty, Balloon↗
PubMed1999

A phase II trial of 200% ProMACE-CytaBOM in patients with previously untreated aggressive lymphomas: analysis of response, toxicity, and dose intensity.

We showed in a phase I trial that the maximum tolerated dose of the ProMACE-CytaBOM regimen in patients with aggressive lymphoma was 200% (Gordon et al, J Clin Oncol 14:1275, 1996). Based on these observations, we initiated a phase II trial designed to determine response, toxicity, and dose intensity using this regimen. We analyzed 74 patients with advanced-stage (III or IV) or bulky stage II aggressive lymphoma. The overall complete response rate was 69% (72% in evaluable patients). With a median follow-up of 4.5 years, the median survival has not yet been reached. The 4-year survival rate is 73% (95% confidence interval [CI] 62, 83%) and no difference was observed among International Prognostic Index (IPI) groups. The 4-year disease-free survival was 71% (95% CI 58, 84%) with no statistical difference between patients with IPI 0 to 1 versus 2 to 4. The toxicity was acceptable, though the grade 4 hematologic toxicity rate for this regimen was 100%. Grade 4 nonhematologic toxicity was 36%. Three cases of either myelodysplastic syndrome or acute leukemia occurred at 7 months, 3.4 years, and 4.2 years after registration. Cytogenic analysis was available in two cases, showing inv(16) without French American British classification (FAB) M4 EO histology in one patient and a 5q-syndrome in the other. These data suggest that 200% ProMACE-CytaBOM with either granulocyte-macrophage colony-stimulating factor (GM-CSF) or G-CSF results in a high complete remission rate and a disease-free survival comparable to any prior risk-based analysis in aggressive lymphoma. Before using this regimen in general practice, phase III clinical trials should be conducted.

Adult↗
PubMed1999

Phase II study of high-dose somatostatin analogue in patients either previously treated or untreated who have extensive-stage small cell lung cancer.

The authors conducted a phase II study of somatostatin analogue in 18 patients with extensive stage small cell lung cancer (four with previous treatment, 14 without previous treatment). Patients received 2,000 mg subcutaneously thrice daily. They were required to have an Eastern Cooperative Oncology Group performance score of 0-2 and acceptable pretreatment biochemical parameters. No patient responded to treatment. The median time to progression was 44 days. The median survival was 106 days. Toxicity related to treatment consisted of mild diarrhea and anorexia. Somatostatin analogue is not active as a single agent in the treatment of extensive-stage small cell lung cancer.

Aged↗
PubMed1999

Interactions between melatonin, reactive oxygen species, and nitric oxide.

Accumulation of reactive oxygen species is critical for the neuropathology of Alzheimer's disease. Melatonin hormone, an antioxidant, could play a key role in aging and senescence. Nitric oxide, a biologically active unstable radical, is synthesized by nitric oxide synthase when converting L-arginine to L-citrulline. We have investigated whether the treatment of cultured cells with melatonin could possibly reduce the release of free radicals and other ROS. We assayed NO indirectly by measuring the level of its stable end products, nitrite/nitrate (NOx), using the Griess reagent. When the neuroblastoma cells such as N1E-115 were treated with a NO donor such as sodium nitroprusside (SNP), a significant level of NOx was detected in a time- and dose-dependent manner in the conditioned medium compared to the untreated cells or SNP-containing media. In neuroblastoma cells, the release of NOx as mediated by SNP was significantly inhibited by treatment with (i) carboxy-PTIO, a NO scavenger; (ii) SOD-1, superoxide dismutase; and (iii) melatonin. In these cells SNP-mediated NOx release was mediated by superoxide ions and/or free radicals that can be inhibited by melatonin. The ROS-scavenging function of melatonin along with its neuroprotective and neurodifferentiating role can be utilized for the prevention of neurodegenerative disorders such as AD.

Animals↗
PubMed1999

Ameliorating effects of thyroxine and atropine in phosphamidon intoxicated chick embryos.

The effects of thyroxine and atropine in ameliorating phosphamidon intoxication in chick embryos was studied. Treatment of phosphamidon significantly enhanced the mortality and abnormality rates, decreased the average body weights, and cholinesterase activity in chick embryos. When thyroxine was administered to the phosphamidon intoxicated embryos, the above parameters changed significantly, indicating an ameliorating effect of thyroxine against phosphamidon intoxication in chick embryos. The combined thyroxine and atropine therapy did not further improve the ameliorating effect. Since in many respects chick embryo development parallels that of mammalian embryos, a short-term use of thyroxine as a protective agent against organophosphate toxicity might be useful.

Animals↗
PubMed1998

The impact of HIV on a fertility problems clinic.

This article describes the impact of the human immuno-deficiency virus (HIV) on clinical infertility practice. HIV is responsible for acquired immuno-deficiency syndrome (AIDS) and first became apparent in 1979, but was not fully recognised by clinicians and scientists until 1981. It is a new disease which now infects large numbers of humans, and there is the possibility that the virulence of the virus may change or mutations may render current testing strategies ineffective. For these reasons, it is important to have a cautious and flexible approach to minimise risk to infertile couples and to future children.

Female↗
PubMed1998

Male fertility disorders.

Effective treatments for extreme oligozoospermia include in vitro fertilization, recovery of sperm through epididymal sperm aspiration or testicular sperm aspiration, and direct injection of sperm through intracytoplasmic sperm injection. The clinical evaluation of and treatment options for male patients with fertility disorders are detailed in this article.

Female↗
PubMed1998

Protective role of thyroxine in methylparathion intoxicated chick embryos.

The efficacy of thyroxine against methylparathion poisoning in chick embryos was studied. The mortality rate and survival rate, frequency of abnormalities, growth rate and size of embryos, and also the change in cholinesterase activity were determined to evaluate the protective effect of thyroxine and atropine. It was observed that the survival rate, growth rate and size, and the cholinesterase activity significantly declined in the methylparathion treated group while the mortality rate and the frequency of abnormalities increased. When thyroxine was given, a significant reversal in these parameters was seen, indicating an effective protective action of thyroxine against methylparathion intoxication in chick embryos. The results also showed that the therapeutic treatment of the combination of thyroxine and atropine did not further improve the effects. Since in many respects, chick embryo development parallels that of mammalian embryos, a short term use of thyroxine as an effective protective agent against organophosphate methylparathion (perhaps other compounds) poisoning may have important implications.

Animals↗