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Biomedical subjects

I Wadsö

Publications and source records attributed to I Wadsö.

At least 19 recordsLinked to original sources
PubMed1992

Effects of pH-variations on the kinetics of growth and energy metabolism in cultured T-lymphoma cells: a microcalorimetric study.

The progression of T-lymphoma cells (CCRF-CEM) growing in suspension has been monitored during long term (12-28 h) batch experiments using microcalorimetry. In parallel with the calorimetric measurements, changes in cell concentration, pH, p(O2) and concentrations of the main energy sources (glucose and glutamine) were determined. The overall metabolic rate per cell (as reflected by the heat production rate per cell, Pcell) and the growth rate decreased with time. These changes could be attributed solely to the decrease in pH of the medium until the total heat production, Q, exceeded 1.2 J per ml (corresponding to an incubation time of 20 h of a batch having an initial cell concentration of 1 x 10(6) cells per ml). The lowering of p(O2) to a level of 0.02 mmol/l or the decrease in concentrations of glucose and glutamine to 7.7 and 1.3 mmol/l, respectively, did not influence Pcell or the growth pattern. No "crowding effect" was observed for the cells in the investigated concentration range (0.6-1.3) x 10(6) cells per ml.

Calorimetry↗
PubMed1991

Cell growth experiments using a microcalorimetric vessel equipped with oxygen and pH electrodes.

A method is described for simultaneous measurements of heat production rate, oxygen activity and pH, using a 3-ml stirred microcalorimetric titration/perfusion vessel fitted with a polarographic oxygen sensor and a combination pH-electrode. Heat production rate (+/- 0.3 microW), pH (+/- 0.01) and oxygen concentration (+/- 4 mumol/l) could be measured without any cross interference between the three signals. Results from measurements on suspensions of T-lymphoma cells and E. coli are presented.

Calorimetry↗
PubMed1990

Microcalorimetric investigations of animal cells.

Calorimetric measurements on living animal cells normally involve determination of heat production rates under essentially isothermal conditions. Experiments are usually performed by use of twin heat conduction microcalorimeters. Combination of results from calorimetric measurements and analytical determinations lead to valuable thermochemical information. But in most studies conducted so far, the calorimeters are used solely as analytical tools, "process monitors". Experiments are easy to perform but several critical experimental parameters should be taken into account.

Animals↗
PubMed1990

Prediction of the cytotoxic effects of some antineoplastic drugs on cultured T-lymphoma cells by microcalorimetry.

The effects on T-lymphoma cells of the antineoplastic drugs Ara-C, cisplatin, vinblastine, chlorambucil and prednimustine were studied by microcalorimetry and a conventional viability assay. The heat production rate for cells was measured immediately after drug treatment and was compared with the change in cell concentration during the following generation time. The results of the microcalorimetric observations were correlated with cell death. Such correlations varied considerably for the different drugs, in particular between chlorambucil and the other drugs investigated.

Antineoplastic Agents↗
PubMed1988

The potential use of microcalorimetry in predictive tests of the action of antineoplastic drugs on mammalian cells.

The effect of methotrexate (MTX) on cultured T-lymphoma cells in a growing suspension was measured by microcalorimetry. The effect of the drug could be observed within 2 h after its injection into the calorimetric vessel. A dose-response curve was constructed from the calorimetric results obtained with final concentrations of MTX in the range of 0.02-2.00 microM. In another series of experiments calorimetric values were determined after 8 h of MTX-cell interaction. These data were correlated with values for cell counts during an 18 h period following the removal of the drug. A clear correlation was found between the calorimetric and cytotoxicity data. Calorimetric results obtained within 8 h of MTX-cell interaction appear to be of value in predicting the antineoplastic effect of the drug.

Animals↗
PubMed1986

Microcalorimetric measurements on tissue cells attached to microcarriers in stirred suspension.

Vero cells growing on microcarriers in stirred suspension were observed calorimetrically using a vessel designed for use with the LKB 'BioActivity Monitor'. Rates of formation of carbon dioxide and lactate were followed in parallel. The results showed that the power and rate of lactate formation could be correlated to both cell number and amount of protein, while the rate of carbon dioxide formation was slightly better correlated to cell number. The power per cell was 27.4 +/- 2.1 pW. Only 33% of this power could be accounted for by the formation of lactate and carbon dioxide.

Animals↗
PubMed1986

A microcalorimetric study of heat production in resting skeletal muscle from human subjects.

Different microcalorimetric techniques have been compared for the assessment in vitro of the total metabolic activity of resting skeletal muscle. Human fibre bundles were suspended in Krebs-Ringer-phosphate buffer containing glucose and insulin and the heat evolution was continuously monitored for 2-6 h. Palmitate as substrate was also tested. The power signals declined rapidly when a static calorimetric method (A) was used. Two different perfusion methods (B, C) gave higher power values. Long-lasting steady states were observed with method C, where the sample was contained in a cage acting as a stirrer. Significant differences were found for fibre bundles from different human muscles as well as age- and sex-related differences. The heat production in samples from the rectus abdominis muscle (method B), 0.73 mW/g muscle wet wt., was significantly higher than for the obliquus internus muscle, 0.44 mW/g, and the vastus lateralis muscle, 0.55 mW/g, but not different from the heat production value of vastus medialis, 0.66 mW/g. In method C particularly, the fibre bundles are believed to be in adequate contact with the surrounding medium. With the use of a multi-channel calorimeter it is possible to perform up to four experiments simultaneously, e.g. involving the calorigenic effects of pharmacological substances. The technique provides a new approach for detailed studies of muscle metabolism in physiological and pathological conditions.

Adolescent↗
PubMed1986

Thermochemistry of the interaction between peptides and vancomycin or ristocetin.

The thermodynamics of the interaction between the glycopeptide antibiotics vancomycin and ristocetin and bacterial peptidoglycan peptide analogs have been studied by means of a microcalorimetric titration technique. From results of the calorimetric measurements, changes in Gibbs energies, enthalpies, entropies and heat capacities for the binding reactions have been calculated. The derived thermodynamic data have been discussed on the basis of stereochemical data available for the interaction of acetyl-D-alanyl-D-alanine with each of the two antibiotics. The significance of entropic factors connected with conformational changes of the antibiotics is stressed.

Calorimetry↗
PubMed1986

Thermochemical characterization of T-lymphoma cells under non-growing conditions.

Cultured T-lymphoma cells, CCRF-CEM, were studied under non-growing conditions by microcalorimetry. A new stirred reaction vessel, mainly designed for biological experiments, was used. The calorimetric results were interpreted by use of known enthalpy data and an assumed net reaction scheme. Of the thermal power measured, 75% could be accounted for by formation of lactate and bicarbonate from the glucose in the medium. It is suggested that the residual power comes from oxidation of intracellular material.

Adenosine Triphosphate↗
PubMed1984

Design and testing of a new microcalorimetric vessel for use with living cellular systems and in titration experiments.

A new microcalorimetric vessel primarily intended for use with living cellular systems and in titration experiments has been designed and tested. The vessel, which forms a modular system, fits into an ampoule measuring cylinder of the LKB 'BioActivity Monitor'. It can be used with different sample cups, volume 1-3 ml, and can be equipped with different types of stirrer and sample holders for cellular materials. Experiments can be performed with or without medium perfusing through the vessel. Small quantities of reagents can be added to the sample compartment during the measurements. Stepwise calorimetric titrations can be performed by an automatic procedure. Test experiments reported include results of measurements with human T-lymphoma cells in stirred suspension and melanoma cells adhered to a polystyrene film in a stirred perfusing medium. Results from titration experiments where N-acetyl-D-alanine was bound to ristocetin A are reported, delta G degree' = -16.5 +/- 0.2 kJ mol-1 and delta H degree' = -32.1 +/- 0.4 kJ mol-1.

Calorimetry↗
PubMed1984

Heat production in human blood lymphocytes. A methodological study.

Heat production rates (thermal power) in peripheral blood lymphocytes from healthy subjects were determined under some defined experimental conditions in an attempt to establish by microcalorimetry a basal metabolic reference range for lymphocytes in the non-activated state. The effects of cell isolation method, the presence of other types of blood cells, cell concentration, temperature, pH and type of suspension medium on the rate of heat production by lymphocytes were evaluated. The results indicate that microcalorimetry is suitable for monitoring the metabolism of these cells with good precision in the physiological range of cell concentration.

Basal Metabolism↗
PubMed1979

Heat production by lymphocytes in chronic lymphocytic leukaemia.

Using microcalorimeters of the thermopile conduction type heat production was measured in lymphocytes from peripheral blood in 8 normals and 10 patients with chronic lymphocytic leukaemia (CLL). The heat production per CLL lymphocyte was lower (1.8 pW/cell) than that found in normal lymphocytes (2.6 pW/cell). Due to the high numbers of lymphocytes in the peripheral blood the estimated heat production of the intravascular lymphocyte pool in CLL was considerably higher than in normals. Since the circulating lymphocytes constitute a minute fraction of the total lymphoid mass in CLL it is suggested that the accumulation of metabolically active lymphocytes in blood and tissues may explain the common clinical signs of hypermetabolism in this disease. The results also indicate that calorimetry may be a useful technique for metabolic studies in suspensions of malignant cells.

Body Temperature Regulation↗
PubMed1978

Calorimetric identification of several strains of lactic acid bacteria.

A microcalorimetric method has been developed for the identification of 9 representative strains of lactic acid bacteria used in the dairy industry. A chemically defined medium containing several carbohydrates gave reproducible and characteristic growth patterns. The technique is proposed as a rapid alternative method for the identification of bacteria selected for commercial use.

Bacteria↗
PubMed1978

Microcalorimetric measurement of normal and adenovirus infected HeLa cells.

The use of a simple microcalorimetric technique for the study of HeLa cells and adenovirus infected HeLa cells has been investigated. The calorimetric curves obtained with these two cellular systems showed characteristic differences. It is concluded that the method can serve as a useful analytical technique for the monitoring of the overall metabolic activity of tissue cells attached to a solid support.

Adenoviridae↗
PubMed1977

Microcalorimetric studies of human platelet metabolism at rest. Influence of pH, temperature, cell concentration, preparation methods and storage.

Heat production in human platelets has been measured under different conditions of pH, temp., cell concentration, preparation and storage time. The heat effect was found to increase linearly in the pH range 7.00-7.95, by 20% per pH unit. The temp. coefficient for the heat effect was determined to be Q10 = 2.0 for the temp. interval 32-42 degrees C. Heat production per cell was not significantly affected by variations in cell concentration, or by storage for several hours at room temp. When citrate replaced heparin as anticoagulant significantly higher heat effect values were found.

Blood Platelets↗