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Biomedical subjects

S Dogra

Publications and source records attributed to S Dogra.

At least 37 records · Page 2Linked to original sources
PubMed2003

Influence of colchicine on pulmonary silicotic fibrogenesis in rats.

With an aim to evaluate the antifibrotic action of colchicine in experimental model of pulmonary silicosis, the effect of colchicine on developing and developed pulmonary silicosis induced by quartz was studied in rats in vivo and on alveolar macrophages exposed to quartz particulates in vitro. A progressive increase in wet and dry weight of lungs exposed to quartz dust alone, and quartz dust and colchicine injected orally was investigated. An increase in collagen contents, with lapse in time, in animals exposed intratracheally to quartz dust, or exposed similarly to quartz dust but receiving colchicine simultaneously through oral route was observed. A blindfold evaluation of histological sections of lungs of silicotic animals with or without colchicine administration during development of lesions did not reveal any difference between two groups of silicotic rats. Administration of colchicine for 4 weeks after the lesions were developed neither inhibited nor retarded the laying down of collagen. The studies were extended to investigate the effect of colchicine on quartz-induced alveolar macrophage cytotoxicity. The presence of varying concentrations of colchicine in the culture medium did not significantly alter cytotoxic potential of quartz. The results reveal that colchicine administration during the development of and on developed silicosis does not significantly alter pathogenesis of silicotic lesions. At the cellular level colchicine does not modulate quartz-induced alveolar macrophage cytotoxicity, believed to be a significant event for the onset of pulmonary silicotic fibrogenesis.

Animals↗
PubMed2001

Tissue cadmium and locomotor behavior following acute inhalation exposure to cadmium aerosol in rats.

Rats were exposed for 1 h to increasing concentrations of cadmium (Cd) through inhalation of cadmium chloride aerosol using nose-only inhalation chambers and depositions of Cd in lungs, liver and kidneys were measured. Changes in spontaneous locomotor activities were recorded 2 and 7 d after cessation of exposure. A concentration dependent increase in Cd in lungs, liver and kidneys was accompanied by significant alterations in spontaneous locomotor response that was dependent on the air Cd concentrations and the postexposure duration. The study shows decreased spontaneous locomotor activity due to Cd accumulation in tissues.

Administration, Inhalation↗
PubMed2000

Brachial plexus nerve block with CT guidance for regional pain management: initial results.

Brachial plexus nerve blocks are performed to treat patients with chronic pain referable to the brachial plexus. The needle insertion and trajectory are based on palpation of surface landmarks. Occasionally, the surface landmarks are difficult to identify owing to body habitus or anatomic alterations secondary to surgery or radiation therapy. The intent of this manuscript is to describe a technique for brachial plexus block guided with computed tomography and to report our initial results for regional pain management.

Adult↗
PubMed1999

Asymmetric distribution of phosphatidylethanolamine in C. albicans: possible mediation by CDR1, a multidrug transporter belonging to ATP binding cassette (ABC) superfamily.

By using two molecular probes, we demonstrate that only 4% of total phosphatidylethanolamine (PtdEtn) in the plasma membrane (PM) of a human pathogenic yeast, Candida albicans, is present in its external half. Evidence is presented to show that the availability of PtdEtn could be related to the expression of a multidrug transporter CDR1 of C. albicans, and the process is energy-dependent. A homozygous CDR1 disruptant strain of C. albicans shows almost 23% reduction in the external labelling of PtdEtn. This report shows that, similar to human MDRs, yeast multidrug transporter could also be involved in aminophospholipid translocation.

ATP-Binding Cassette Transporters↗
PubMed1999

Antibody forming cell response to nickel and nickel-coated fly ash in rats.

The potential of nickel as nickel chloride, native fly ash and Ni-coated fly ash to alter pulmonary and systemic immune response was evaluated upon intratracheal (I/T) exposure of rats. The animals were sensitised with sheep red blood cells (SRBC) through I/T and intraperitoneal (I/P) routes. Nickel exposure resulted in a decrease in the number of antibody forming cells (AFC) in lung associated lymph nodes (LALN) and spleen. In rats exposed to native fly ash there was a reduction in the number of AFC in LALN but not in spleen. The results did not demonstrate any significant difference in the immunosuppression of fly ash and Ni-coated fly ash exposed rats. The decrease in AFC formation in Ni-coated fly ash exposed animals was of a lesser magnitude than in rats exposed to Ni-alone.

Administration, Inhalation↗
PubMed1997

Tuberculous osteomyelitis.

Tuberculous osteomyelitis which does not involve a joint is uncommon and may fail to be diagnosed by an orthopaedic surgeon. We treated 28 lesions of tuberculous osteomyelitis in 25 patients between 1988 and 1995. The duration of symptoms was from two to 39 months, and most of our patients had been treated initially with non-steroidal anti-inflammatory drugs which failed to provide relief. Bone pain which does not promptly respond to analgesic medication is often due to infection or neoplasia. In the early stages, when plain radiographs are normal, MRI or CT may help to localise lesions. On plain radiographs, more advanced lesions may mimic chronic pyogenic osteomyelitis, Brodie's abscess, tumours or granulomatous lesions. Biopsy is mandatory to confirm the diagnosis, and antituberculous drugs are the mainstay of treatment. When operative findings at biopsy have the features of skeletal tuberculosis curettage of the affected bone may promote earlier healing.

Adolescent↗
PubMed1996

Pulmonary clearance of Candida albicans: effect of exposure to native and metal-coated fly ash.

The viability of Candida albicans was tested at various intervals in the lungs of rats following single intratracheal inoculation of the yeast cells. Most of the inoculated cells were cleared from lungs within 48 hr after exposure. Clearance was enhanced in lungs exposed to metal-coated fly ash than in those exposed to native fly ash. The validity of these studies was verified in vitro using peritoneal macrophages of mice exposed in vivo to native and metal-coated fly ash. An increase in phagocytic and intracellular killing of macrophages harvested from animals exposed to native or metal-coated fly ash was observed.

Animals↗
PubMed1995

Alterations in the pulmonary and systemic immune response in rats exposed to coal fly ash.

The effect of intratracheally injected fly ash on the development of pulmonary and systemic immunity was studied in rats. Following intratracheal and intraperitoneal immunisation with sheep red blood cells (SRBC) there was an appearance of antibody forming cells (AFC) in lung associated lymph nodes (LALN) of animals exposed to either fly ash or physiological saline. Enumeration of AFC in LALN after immunisation by either of the routes, revealed a reduction in the number of AFC in LALN of fly ash exposed rats in comparison to saline exposed animals. The reduction in the number of AFC was more pronounced after exposure of Cd-coated fly ash. The AFC appeared in the spleen only after immunisation through intraperitoneal route and the number of AFC in spleen of the fly ash and saline exposed group of animals did not show any significant difference. These results demonstrate that fly ash burden of lungs results in an impairment of the local immune response of the lungs without an associated effect on the systemic immunity.

Air Pollutants↗
PubMed1995

Effect of long and short fibre amosite asbestos on in vitro TNF production by rat alveolar macrophages: the modifying effect of lipopolysaccharide.

The influence of long and short fibre amosite on the generation of tumor necrosis factor (TNF) by rat alveolar macrophages was investigated in vitro. TNF rich supernatants were prepared from macrophages cultured in F10 medium +2% Bovine Serum Albumin (BSA). Spontaneously released TNF from unstimulated macrophages and TNF rich supernatants from macrophages exposed to Lipopolysaccharide (LPS) and fibres were stored at -70 degrees C and then tested for their cytotoxicity towards L929 cells. Maximum spontaneously released TNF was obtained from 24 hour macrophage cultures. Short amosite fibres had no significant effect in stimulating alveolar macrophages to release TNF while the 50 micrograms dose of long fibres resulted in significantly increased release of TNF. Cotreatment of alveolar macrophages with LPS and fibres further enhanced the TNF production and maximum production was obtained with LPS +50 micrograms dose of long fibre resulted in significantly increased release of TNF. Co-treatment of alveolar macrophages with LPS and fibres further enhanced the TNF production and maximum production was obtained with LPS +50 micrograms of long fibre amosite. The present study indicates that fibre dimension is a major factor in in vitro dust activity and TNF has a possible active role to play in dust induced inflammation in vivo.

Animals↗
PubMed1995

Pattern of injuries in a hydro-electric project.

A study of work-related injuries at a hydro-electric project site (May 1991-April 1992) was undertaken to determine the incidence and pattern of the injuries out of a total number of 119 injuries in the year. A significant proportion of these were orthopaedic in nature and the commonest site of injury was limbs (both upper and lower limbs) like auto-amputations and head injuries. A large proportion of these accidents (24.37%) resulted in permanent disability likely to interfere in the normal activities or locomotion of those injured.

Accidents, Occupational↗
PubMed1994

Stable heterologous expression of hydroxysteroid sulphotransferase in Chinese hamster V79 cells and their use for toxicological investigations.

Various benzylic alcohols are metabolically activated to electrophilic, potentially mutagenic and carcinogenic sulphuric acid esters. The involved sulphotransferases are not expressed in the cell lines in culture which are commonly used for mutagenicity testing. The liver of adult female rats is very efficient in the bioactivation of 1-hydroxymethylpyrene. The major enzyme involved was purified and identified as hydroxysteroid sulphotransferase a. Its cDNA was stably expressed in Chinese hamster V79 cells, which are particularly suited for the quantitative detection of various types of mutations and other genotoxic and cytotoxic effects. The mRNA, protein and enzyme activity levels in the constructed cell lines (V79rSTa-1 and V79rSTa-2) were measured, and the cells were also used in mutagenicity and cytotoxicity investigations with benzylic alcohols. 1-Hydroxymethylpyrene, 9-hydroxymethylanthracene and 6-hydroxymethylbenzo[a]pyrene showed enhanced cytotoxicity in V79rSTa-1 and V79rSTa-2 cells, as compared with sulphotransferase-deficient control cells. In addition, 1-hydroxymethylpyrene induced sister chromatid exchanges, and 6-hydroxymethylbenzo[a]pyrene induced gene mutations in V79rSTa-1 cells. We intend carrying out more investigations with other chemicals on these cell lines. Their advantages, as compared with systems with external metabolising systems, include the formation of the active metabolites within the target cell, as in ST-proficient cells in vivo, eliminating the problems which may result from restricted intercellular transport of reactive and ionized sulphuric acid conjugates. Furthermore, cells expressing other sulphotransferases, including human enzymes, may be constructed and used for comparative investigations.

Animals↗
PubMed1992

Asbestos-stimulated tumour necrosis factor release from alveolar macrophages depends on fibre length and opsonization.

Fibre length has been shown to be an important factor in the ability of respirable fibres to cause lung fibrosis and cancer. We have reported that a long sample of amosite asbestos is more carcinogenic and fibrogenic than a short sample of similar diameter. These amosite asbestos samples were studied with regard to their ability to stimulate the release of the pro-inflammatory cytokine tumour necrosis factor (TNF) from rat alveolar macrophages in vitro. The long fibre sample was found to stimulate substantially greater release of the cytokine than the short sample. Furthermore, on treatment of the fibres with rat immunoglobulin G (IgG), there was an increase in the ability of both the long and the short sample to stimulate TNF secretion, although the long sample retained by far the greatest activity. Coating of the fibres with a range of other proteins had no substantial effect on their ability to stimulate TNF secretion. Quartz and titanium dioxide (TiO2) were included as control particles and the TNF-stimulating activity of quartz was notably increased by opsonization with IgG. TiO2 showed a similar low activity to that of the short fibre sample of amosite but this again could be modestly increased by opsonization with IgG. The simulation of TNF release caused by treatment with immunoglobulin-opsonized long fibre amosite could be inhibited by treatment of the macrophages with the protein kinase C-inhibitor staurosporine. The study demonstrates a fibre length-related ability to stimulate cytokine secretion by alveolar macrophages, and its enhancement by opsonization with IgG.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗