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Biomedical subjects

S Kar

Publications and source records attributed to S Kar.

At least 163 records · Page 9Linked to original sources
PubMed1981

Proliferation and lymphocyte stimulatory capacity of Theileria-infected lymphoblastoid cells before and after the elimination of intracellular parasites.

A prominent pathogenic facet of Theileria infections is that the parasite infects lymphocytes and 'transforms' them into parasitized lymphoblastoid cells which are highly proliferative and can be cultured indefinitely in vitro. To analyse the relationship between the intracellular parasite and lymphocyte transformation we have studied the effects of eliminating parasites from these lymphoblastoid cells using the naphthoquinone derivative 993.C. Treatment of Theileria-infected lymphoblastoid cells with 993.C gradually eliminates intracellular parasites but cell proliferation is not inhibited until several days after parasite elimination. The proliferating cells no longer contain schizont particles and are medium-sized lymphocytes and small blast cells. The surface phenotype of these cells, as defined by lectins and monoclonal antibodies, remains unchanged after parasite elimination. The division of non-parasitized cells, under the culture conditions examined, was not indefinite. The compound 993.C itself does not appear to be mitogenic and possible mechanisms for this continued division are discussed. It has been previously reported that co-cultivation of irradiated Theileria-infected lymphoblastoid cells with autologous lymphocytes induces marked DNA synthesis in the latter. We examined further the relevance of this observation for immunity to Theileria by using lymphoblastoid cells treated with 993.C. Elimination of intracellular parasites by this compound does not impair the ability of these cells to stimulate DNA synthesis in autologous lymphocytes. Furthermore, lymphocytes from Theileria-immune or non-immune cattle react similarly. The reaction differs from a classical mixed lymphocyte reaction induced by antigens encoded in the main histocompatibility complex since the stimulator cells are exclusively T lymphocyte-derived cells, the magnitude of response is greater and stimulated lymphocytes are able to act as 'stimulator cells' to fresh autologous lymphocytes. Thus we question the immunological relevance of the observed lymphocyte division. The possibility that Theileria-infected lymphoblastoid cells carry viral genomes or infectious virus particles is discussed. Preliminary electron microscopic studies have not revealed any virus particles.

Animals↗
PubMed1979

Effect of nutrients on the toxicity of pesticides carbofuran and hexachlorocyclohexane to blue-green alga Nostoc muscorum.

The effects of various levels of nutrients like potassium phosphate (dibasic), calcium nitrate, and calcium chloride individually and in combinations were studied on the toxicity of the commonly used pesticides carbofuran and hexachlorocyclohexane (HCH) in growth medium to the N2-fixing blue-green alga Nostoc muscorum. It was observed that all these chemicals had some effects on toxicity. The toxicity of both carbofuran and HCH was reduced to some extent in the presence of higher concentrations of the nutrients when compared to normal levels of the chemicals in the medium. The higher doses of nutrients in combinations antagonized the effect of individual treatment and enhanced the toxicity of pesticides.

Calcium Chloride↗
PubMed1978

Toxicity of carbofuran to blue-green alga Nostoc muscorum.

Effect of commercial grade pesticide furadan (3% a.i. as carbofuran) was studied on the survival, growth and nitrogen fixation of blue-green alga Nostoc muscorum. The lower concentration of furadan i.e. 25 microgram/ml enhanced survival, growth and nitrogen fixation in the alga whereas these were gradually inhibited in higher concentrations (50--1000 microgram/ml) and the presence of more than 1200 microgram/ml was algicidal. The preliminary observations revelaed that pesticide is biodegraded by the alga.

Carbofuran↗
PubMed1978

Effect of pH, light intensity and population on the toxicity of the pesticide carbofuran to the blue-green alga Nostoc muscorum.

The effect of pH, light intensity and population on the toxicity of the pesticide furadan (containing 3% carbofuran as the active ingredient) was studied on the nitrogen fixing blue-green alga Nostoc muscorum. It was observed that all these factors had effects on the toxicity of the pesticide. The blue-green alga grew better in the pH range of 7.5-10, whereas the acidic pH of 5-6 retarded growth. The pesticide was more toxic to alga in the medium of pH 5-6, whereas reduction in toxicity was noticed in alkaline pH of 7.5-10. The alga grew slowly in a light intensity of 1,500 lux in comparison to a light intensity of 3,000 lux, and no growth occurred in the dark. The toxicity of the pesticide gradually decreased with increasing light intensity. The toxic effect of the pesticide was increased when the initial population level was low, and increasing the initial population reduced the toxicity.

Carbofuran↗
PubMedDate not supplied

Percutaneous optical imaging system to track reporter gene expression from vasculatures in vivo.

This study develops a percutaneous optical imaging system for tracking fluorescent reporter gene expression in vasculatures. We build a percutaneous optical imaging system that primarily comprised a 1.5-mm, semi-rigid, two-port optical probe. The performance of the optical probe is first tested in vitro with cell phantoms, and then the feasibility of the percutaneous optical imaging system is validated in vivo in eight femoral artery segments of two pigs. The green fluorescent protein (GFP) gene is locally delivered into four arterial segments, while saline is delivered to the four contralateral arterial segments as controls. The targeted arteries are localized using color Doppler, and thereafter the optical probe is positioned to the target arterial segments under ultrasound guidance. Optical imaging captures are obtained using different exposure times from 10 to 60 s. Subsequently, the GFP- and saline-targeted arteries are harvested for fluorescent microscopy confirmation. The percutaneous optical probe is successfully positioned at a distance approximately 2 mm from the targets in all eight arteries. The in-vivo imaging shows higher average signal intensity in GFP-treated arteries than in saline-treated arteries. This study demonstrates the potential using the percutaneous optical imaging system to monitor, in vivo, reporter gene expression from vasculatures.

Animals↗
PubMedDate not supplied

High volume sutureless intraocular lens surgery in a rural eye camp in india.

BACKGROUND AND OBJECTIVE: To describe the use of small incision sutureless cataract surgery (SISCS) that permits high-volume, high-quality, and low-cost surgery. PATIENTS AND METHODS: We compared the speed, safety, and visual results of 1190 surgical techniques performed in a public eye camp in India. Intraocular lenses were received by 97% of patients (1154). Surgical techniques used were SISCS, phacoemulsification, and standard extracapsular cataract extraction (ECCE) technique. RESULTS: Postoperatively, 60.0% attained uncorrected vision of 6/24 or better. There was little difference in visual results or complication rates among the three techniques. The most striking finding is the speed of SISCS, which enables experienced surgeons to perform the technique in 3.8 to 4.2 minutes. CONCLUSION: We believe this surgical technique is of major importance especially in developing nations facing enormous surgical volumes and limited resources.

Humans↗
PubMedDate not supplied

Experimental evaluation of a new transducer tipped catheter.

The accuracy and fidelity of a new transducer-tipped catheter (Camino Laboratories) was compared in 10 closed chest anesthetized dogs with standard Millar catheters. Simultaneous Camino and Millar measurements of left ventricular pressures and its first derivative (dp/dt) were recorded in control, after Isoprenaline infusion and during left anterior descending coronary artery balloon occlusion, to vary the pressures for comparison. Linear regression analysis comparing the Camino and Millar systems yielded a good correlation, and one way analysis of variance showed no difference between the two catheter readings, thus revealing that the recently developed Camino disposable transducer-tipped catheter provides accurate measurements of left ventricular pressure and its first derivative.

Animals↗