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C Ghosh

Publications and source records attributed to C Ghosh.

49 records · Page 3Linked to original sources
PubMed1993

Iron/ascorbate-induced lipid peroxidation changes membrane fluidity and muscarinic cholinergic receptor binding in rat frontal cortex.

Lipid peroxidation (LP) is a complex process which involves the formation of lipid free radicals and leads to oxidative damage. LP has also been implicated in several neurodegenerative diseases as well as aging. In the present study, we evaluated the effects of the induction of LP in vitro on muscarinic cholinergic (Mch) receptor binding and membrane fluidity in rat brain. Membranes from the rat frontal cortex were peroxidized by adding ferrous sulphate (84 microM) and ascorbic acid (400 microM). Peroxidation was measured as the amount of thiobarbituric acid reactive products formed (nmol malondialdehyde/mg protein). Mch receptor binding was measured 10, 20 and 30 min after peroxidation. Membrane fluidity was evaluated by fluorescence polarization studies using two probes; 1,6-diphenyl-1,3,5-hexatriene (DPH) and 1-[4(trimethylamino)phenyl]-1,3,5-hexatriene (TMA-DPH). Significant alterations in Mch receptor binding (decreased Bmax and increased Kd) were found after peroxidation. Membrane fluidity was also significantly decreased after peroxidation as observed with both probes. The decrease in membrane fluidity was due to an increased cholesterol to phospholipid molar ratio after peroxidation. These data suggest that lipid peroxidation induces changes in membrane dynamics as detected by the fluorescent probes and such changes in membrane microviscosity may be the cause for alterations in Mch receptor kinetics.

Animals↗
PubMed1993

Sarcoptes scabiei in animals spreading to man.

An outbreak of Sarcoptes scabiei in animals was observed from mid-November 1991 to mid-December 1991 in two adjacent villages, Fewgram and Nurpur, in Birbhum District, West Bengal State, India, starting from goats to cattle, then to sheep and even to dogs. Nineteen goats and one cattle died of manage infection. The infection spread to man in the last week of December 1991, and affected forty-two human beings, tending and rearing animals. The animals treated with deltamenthrin (synthetic pyrethroid) and amitraz (triazapentadiene) were completely cured. In man, the disease seemed to be self-limited in some cases and 2% hexachlorobenzene was successfully used for treatment of the others. The outbreak was effectively controlled in March 1992.

Adult↗
PubMed1992

Fluctuation of serum phenytoin concentrations during autologous bone marrow transplant for primary central nervous system tumors.

We reviewed our experience for adult patients receiving oral anticonvulsant therapy during high-dose chemotherapy and autologous bone marrow re-infusion for primary malignant tumors of the central nervous system. Nineteen patients received either iv carmustine (BCNU) 900-1050 mg/m2 and 6120 cGy cranial irradiation (N = 10), iv carmustine 900-1050 mg/m2 and iv cisplatin 200 mg/m2 (N = 8), or iv carmustine 600 mg/m2, iv cisplatin 200 mg/m2, and iv etoposide 2400 mg/m2 (N = 1). Anticonvulsant therapy consisted of phenytoin alone (N = 8), phenobarbital alone (N = 4), carbamazepine alone (N = 2), phenytoin and carbamazepine (N = 2), carbamazepine and phenobarbital (N = 1), and no anticonvulsant therapy (N = 2). Serum anticonvulsant concentrations were monitored frequently and doses adjusted to keep values in the therapeutic range. While phenobarbital and carbamazepine doses remained relatively stable, all patients required increased doses of phenytoin anticonvulsant therapy after beginning chemotherapy (mean onset 3.7 days after initiation of chemotherapy). The increase in phenytoin dose ranged from 50% to 300% above baseline (mean 134%). By the time of discharge from the hospital (approximately 3-4 weeks after the start of chemotherapy) anticonvulsant dose was decreased to near pre-therapy levels. These swings coincided with the initiation of dexamethasone therapy for antiemetic effect and were more pronounced in patients also receiving cisplatin therapy. Due to close monitoring of serum phenytoin concentrations, no instances of toxicity due to excessive drug concentration, or seizures due to subtherapeutic doses, were noted in patients with primary CNS malignancies. Serum phenytoin concentrations fluctuate markedly during high-dose chemotherapy and must be analyzed frequently during the course of therapy.

Adult↗
PubMed1990

Fluidity-dependent Mg2(+)-ATPase activity in membranes from Leishmania donovani promastigotes.

The state of the lipid phase of the membrane plays a key role in the exposure of various receptors, antigens and enzymes on the membrane surface. The fluidity of membranes of Leishmania donovani promastigotes was monitored by two independent methods, i.e. influx of sterol from liposomes and removal of phospholipids by treatment with phospholipase C. The altered sterol/phospholipid ratio, in both cases, provided evidence that the activity of the functionally important membrane-bound enzyme Mg2(+)-ATPase is modulated by the state of the lipid phase of the membrane.

Animals↗
PubMed1989

Computed tomography-guided retroperitoneal biopsies.

A retrospective review was performed on consecutive patients who had a computed tomographic (CT) biopsy of the retroperitoneum at University Hospitals of Cleveland. Biopsies were performed using a 20-gauge Chiba needle (University Medical Instruments Corp, Ballston Spa, NY) and a 14-gauge Tru-Cut needle (Baxter Pharmaseal, Valencia, CA). The results included success rate, failure, and complications, and were determined by a review of patient charts, surgical results, and autopsy results. The 20-gauge needle aspirations were accurate in suggesting the diagnosis in 20 of 22 cases of metastatic disease and ten of 15 cases of lymphoma. Using the 20-gauge needle, it was not possible to make a specific diagnosis in any of the lymphoma patients or for unusual benign disorders. With the 14-gauge Tru-Cut needle, the correct diagnosis was made in 13 of 13 cases of metastatic disease, ten of 11 cases of lymphoma, and two of 2 cases of unusual benign disorders. It was also possible to make the specific diagnosis of the lymphoma type in ten of 11 cases. The only complication was a small subcutaneous hematoma following a biopsy with a 20-gauge Chiba needle.

Biopsy, Needle↗
PubMed1988

Leishmania donovani: role of microviscosity of macrophage membrane in the process of parasite attachment and internalization.

Host macrophage infection by the parasite Leishmania donovani is heterogeneous, but it is not clear which factors are responsible for parasite recognition within the macrophages. One possible factor may be the alteration of the microviscosity of the macrophage membrane. This in turn may affect receptor expression and hence parasite infection. In this paper we describe alteration of the lipid composition and hence the microviscosity of the macrophage membrane in a controlled manner using liposome fusion technique. At a higher macrophage membrane microviscosity a larger number of parasites have been found to adhere to the macrophage surface. However, the proportion of parasites finally internalized when compared to parasites adhering to macrophages is inversely correlated with the artificially altered macrophage membrane microviscosity. The process of endocytosis has been examined in both native and lipid modified macrophages in the presence of several sugar antagonists. The results indicate (i) glucose and mannose are specifically involved in the binding process, and (ii) the microviscosity has a key role in controlling the macrophage parasite interaction. The results obtained so far support a model of endocytosis where expression of the receptor is a critical initial process dependent on the microviscosity of the membrane.

Animals↗
PubMed1979

Identification of the prosthetic group of urocanase. The mode of its reaction with sodium borohydride and of its photochemical reactivation.

Urocanase from Pseudomonas putida and from beef liver were isolated by modifying described procedures. Both enzymes were inactivated and labeled on treatment with tritiated sodium borohydride and gave, upon subsequent hydrolysis, a radioactive acid. The previously reported identity of this acid as 2-hydroxybutanoic acid was disproved by several criteria. Other hydroxy acids were also proved to be different from the radioactive acid derived from urocanase. A large portion of the radioactive material from P. putida was found to be nicotinic acid by 1H NMR spectroscopy, gas-liquid chromatography of its methyl ester, and co-crystallization with authentic reference compounds both as the acid and as the hydrazide. A significant portion of the radioactive material derived from beef liver urocanase also co-crystallized with nicotinic acid. Sodium borohydride-treated inactive urocanase was partially reactivated by light. The action spectrum of the photoreactivation showed a maximum at 330 nm. Treatment of urocanase with sodium borodeuteride followed by hydrolysis afforded a sample of nicotinic acid which carried deuterium mainly in position 6. Both the reversible reducibility of urocanase and its action spectrum of photoreactivation suggest that urocanase contains an enzyme-bound nicotinamide nucleotide molecule which is essential for enzymic activity.

Animals↗
PubMedDate not supplied

Increased vulnerability of neuronal cell lines to sodium nitroprusside-mediated toxicity is caused by the decreased level of nitric oxide metabolites.

Nitric oxide (NO) is an unstable radical produced during the oxidative deamination catalyzed by NO synthase (NOS) that converts L-arginine to L-citrulline. NO is also generated nonenzymatically from a group of compounds, called NO donors, such as sodium nitroprusside (SNP). NO directly or through its metabolites has been implicated in several disorders, including Alzheimer's disease (AD). Since NO is a highly labile unstable free gas, we measured the stable end products, nitrite and nitrate (NOx). Here, we investigated the effect of SNP-mediated NO release in different cell types and its effect on the beta-amyloid precursor protein (betaAPP). When different cell types were induced with SNP, a significant level of NOx was detected in a time and dose-dependent manner over the spontaneous release of NOx by SNP. The astrocytes, glial, and epithelial cell lines released significantly higher level of NOx as compared to neuronal cells following the exposure of SNP. The latter group of cells was more sensitive to NO-mediated cytotoxicity, as demonstrated by the lactate dehydrogenase assay. The SNP-mediated toxicity is known to be caused by the accumulation of cyanide ions and we report that the ability of cells to protect against it depends on the levels of nitric oxide metabolites. Cell lines, such as astrocytic and epithelial, that produce more NOx are better protected against the SNP-induced toxicity than the less NOx-protecting neuronal cell lines. The possibility of differential susceptibility of neurons and astrocytes resulting from the different content of reduced glutathione is also discussed. The release of NOx was prevented by cotreatment with a NO scavenger and superoxide dismutase but not by a NOS inhibitor. The activity of NOS was decreased when cytosolic extracts were incubated with SNP. In the conditioned medium of SNP-induced cells, the level of soluble betaAPP (sAPP) was decreased, and this decrease was more apparent in neuronal than astrocytic cell lines. Taken together, these results suggest that the SNP-derived NO release is independent of the NOS pathway, that various cell types metabolize SNP differently, and that neuronal cell lines are more vulnerable with SNP treatment with lowered sAPP secretion. Since the neuronal cell lines lack a nitric-oxide-generated protective mechanism, we speculate that these cells may be the first targets of neurodegeneration by several toxic agents, including the cyanides and peroxynitrites.

Amyloid beta-Protein Precursor↗