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D Sarkar

Publications and source records attributed to D Sarkar.

121 records · Page 7Linked to original sources
PubMedDate not supplied

Leishmania donovani attachment stimulates PKC-mediated oxidative events in bone marrow-derived macrophages.

We investigated activation signaling events in bone marrow-derived macrophages after infection with Leishmania donovani, an intracellular parasite of macrophages. Leishmania donovani infection caused a general suppression of activation parameters like O2- and NO production. However, conditions which allow parasite attachment and prevent entry resulted in triggering of O2- and NO production and stimulation of O2 consumption. Optimal NO and O2- production occurred when bone marrow-derived macrophages and Leishmania ratio was 1:100. The activation signal for O2- production was initiated 15 min after parasite attachment, whereas augmentation of NO production started 6 h after attachment Activation of O2- and NO generation by L. donovani attachment was inhibited by staurosporine as well as by prolonged treatment of phorbol myristate acetate suggesting a protein kinase C-dependent mechanism. Translocation studies showed that protein kinase C activity in cell membrane fraction rapidly and transiently increased following parasite attachment. No such protein kinase C translocation event occurred in L. donovani infected bone marrow-derived macrophages. Phorbol myristate acetate was found to stimulate membrane translocation of protein kinase C in parasite attached cells whereas it was impaired in infected cells. However, both attachment and infection induced a similar shift of phorbol receptors from cytosolic to membrane fraction indicating that in infected cells the translocation of protein kinase C protein was not impaired but the activity of the membrane associated enzyme was somehow inhibited. These results suggest that although internalization of intracellular parasites like L. donovani caused inhibition of nitrite and superoxide release, mere attachment on macrophage surface resulted in an activation of protein kinase C-mediated downstream oxidative events.

Animals↗
PubMedDate not supplied

Phytoavailability of biosolids phosphorus.

Efficient utilization of biosolids P for agronomic purposes requires accounting for differences in the phytoavailability of P in various biosolids. Greenhouse studies were conducted with a common pasture grass grown in two P-deficient soils amended with 12 biosolids and a commercial fertilizer (triple superphosphate, TSP) to quantify P uptake and to assess the relative phytoavailabilities of the P sources. Biosolids were grouped into three general categories of phytoavailability relative to TSP: high (> 75% of TSP), moderate (25-75% of TSP), and low (< 25% of TSP). Two biosolids, produced via biological phosphorus removal (BPR) processes, were in the high category, and mimicked fertilizer P with regard to P phytoavailability. Most biosolids produced by conventional wastewater and solids digestion and additional treatments like composting were in the moderate category. Also included in this category was a BPR that had been pelletized and another BPR supplemented with Al. The low category included biosolids containing greater than normal (> 50 g kg(-1)) total Fe and Al concentrations and processed to high (> 60%) solids content.

Agriculture↗
PubMedDate not supplied

Perceptions and attitude towards tobacco smoking among doctors in Chandigarh.

Two hundred and eighteen randomly selected doctors drawn from among the faculty and students of Postgraduate Institute of Medical Education and Research; Interns and staff at the General Hospital; and General practitioners of the Chandigarh city, were administered a structured questionnaire. Among them 31.6% were current smokers whereas 23.3% had stopped smoking (ex-smokers). All but one of the smokers were men who smoked cigarettes. Spirit of experimentation and peer influence were important initiating factors whereas the habit was continued mainly to concentrate on work/study. Doctors were uniformly aware of the detrimental effects of smoking, particularly its association with lung cancer, chronic bronchitis and coronary artery disease, and this was the major reason for their abstaining or wanting to quit the habit. The relation of smoking with oral cancer, laryngeal cancer, emphysema and peripheral vascular disease was not well appreciated. Counselling patients about hazards of smoking was practised significantly less often by smoking doctors and surgeons. The options favoured by doctors for preventing smoking included a ban on tobacco advertising, specific health warning on cigarette/bidi packs, and restriction of smoking in public places, particularly hospitals and clinics.

Adult↗