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Biomedical subjects

I Wadsö

Publications and source records attributed to I Wadsö.

At least 37 records · Page 2Linked to original sources
PubMed1982

Simultaneous determination of delta G, delta H and delta S by an automatic microcalorimetric titration technique. Application to protein ligand binding.

A methodological study has been made with a syringe titration unit attached to an LKB batch microcalorimeter. The precision and accuracy of the instrument assembly have been evaluated by neutralization reactions and by dilution of sucrose solutions. As an example, heat quantities on the order of 10 mJ accompanying the addition of 10 microliter titrant solution could be determined with an accuracy of better than 1%. A stepwise titration procedure was used to characterize the binding of indole-3-propionic acid to alpha-chymotrypsin. The following thermodynamic data were obtained (25 degrees C, acetate buffer, pH 5.80): delta G0=-18.46 +/- 0.17 kJ X mol-1, delta H0=-15.26 +/- 0.20 kJ X mol-1, delta S0 = 10.85 +/- 1.21 JK-1 X mol-1.

Calorimetry↗
PubMed1982

Heat production in different populations of human blood cells exposed to immune complexes in vitro: the importance of the Fc parts of immunoglobulins and the influence of active complement.

By use of a batch microcalorimeter of the thermopile type, heat production was measured in isolated populations of human peripheral blood cells exposed to defined immune complexes formed in vitro. It was found that most of the heat production recorded in whole blood after admixture of immune complexes occurs in the granulocytes. Under these conditions small but constantly higher activation values were found in the absence of active complement. It was shown that complexes consisting of antigen and F(ab)2 fragments prepared from the specific antibodies were able to initiate heat production in the cells only in the presence of active complement. These experiments indicate that immune complexes are able to induce increased heat production in the cells either by binding to Fc receptors or by activation of complement through the alternative pathway and subsequent binding of the generated C3b to C3b receptors on the heat-producing cells.

Antigen-Antibody Complex↗
PubMed1981

Metabolic activity of lymphoma cells and clinical course in non-Hodgkin lymphoma (NHL).

By microcalorimetry the metabolic activity of malignant cells from 2l patients with non-Hodgkin lymphoma was monitored. Heat production, a measure of the metabolic activity of cells, showed positive correlation with the clinical course of the disease. The heat produced by tumor cells from patients with progressive disease was 5.5 pW/cell, while that from patients responding to treatment was 3.l pW/cell. The difference between the 2 groups is significant (P less than 0.05). A higher heat production was obtained in tumor cells from 7 out of 10 patients who were unresponsive to the therapy when compared with cells from 11 patients who had become asymptomatic as a result of the same therapy. Also heat production from blood lymphocytes was found to be higher (P less than 0.005) in the group of patients with progressive disease as compared to the group of patients who responded to therapy. The present results indicate an association between high heat production in lymphoma cells and blood lymphocytes and a poor prognosis.

Aged↗
PubMed1980

A new approach to detection of antigen-antibody complexes by microcalorimetric measurements of heat production in blood cells.

Using batch microcalorimeters of the thermopile conduction type, heat production was measured in human blood in the presence of defined antigens and their specific antibodies. A large increase in heat production, reflecting increased metabolic activity in the blood cells, was found when antigens and specific antisera at certain antigen-antibody proportions were mixed with the blood. The reproducibility and specificity of the method were found to be very good. The present results indicate that calorimetry may be a useful technique for detection of antigen-antibody complexes.

Animals↗
PubMed1980

Microcalorimetric measurement of production heat in isolated human adipocytes.

A method for the quantitative measurement of heat production in isolated human adipocytes is described. Fat cells are isolated by collagenase treatment of biopsy specimens of adipose tissue, and heat production measured by microcalorimetry. The heat effect was constant for at least 4 h. Heat values increased with increasing pH (about 6% per 0.1 pH unit) and temperature (about 9% per degrees C at 37 degrees C). The apparent activation energy was calculated as 44 kJ/mol. Heat production was about 50% higher in cell suspensions containing glucose and insulin. Imprecision was about 6.5% (coefficient of variation) and sensitivity allowed measurements in samples containing 20-30 mg adipocyte lipid. Heat production in normal volunteers under standardized conditions (i.e. in Krebs-Ringer-bicarbonate buffer pH 7.4, at 37 degrees C and in the presence of 11 mmol/l glucose and 0.1 U/ml insulin) was 133 +/- 48 (mean +/- SD) microW/g adipocyte lipid weight, corresponding to 49 +/- 15 pW/cell. The technique seems of importance for the characterization of energy balance in the fat cell under normal and pathophysiological conditions.

Adipose Tissue↗
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↗
PubMed1976

An equation of state describing hydrophobic interactions.

Several thermodynamic properties for the process of dissolution of pure hydrocarbons into water are found to be linearly related to the number of hydrogens on the hydrocarbon molecule. From the correlations found for the Gibbs energy change, enthalpy change, and heat capacity change, along with the use of an average minimum solubility temperature, an equation of state for the hydrophobic effect is derived. The entropy change upon dissolution per hydrocarbon hydrogen atom is close to -R ln 2. A model based upon a "tetrahedrally" localized water molecule with one corner defined by a carbon-hydrogen group and the other three corners defined by water molecules is used to estimate the observed entropy and heat capacity changes.

Journal Article↗
PubMed1976

Microcalorimetric detection of growth of Mycoplasmatales.

A static ampoule microcalorimeter was used to study the growth of mycoplasmas, acholeplasmas and ureaplasmas. Growth as indicated by thermograms was compared with the results of conventional methods, namely, terminal dilution counts, plate counts, turbidimetric measurements, glucose consumption and pH changes. Removal of oxygen had little effect on mycoplasma growth. The microcalorimetric method is potentially useful for identifying and enumerating the members of the Mycoplasmatales.

Acholeplasma↗
PubMed1976

Microcalorimetric measurements of heat production in human erythrocytes. Heat effect during methylene blue stimulation.

The metabolic activity in human erythrocytes during stimulation with 10(-4) mol/l methylene blue has been studied by a microcalorimetric method. Simultaneous measurements were performed on cells from the same preparation suspended in different media. Mean values for the ratios between heat effect values were 7.1 +/- 1.0, 7.4 +/- 0.8, and 10.2 +/- 1.7 (+/- S.D.) for cells suspended in plasma, serum, and glucose phosphate buffer, respectively. All heat effect values were corrected to pH 7.40 using the correction factor found in the present work (0.4 % per 0.01 pH unit). The present calorimetric results are in qualitative agreement with previous reports of other investigators concerning the stimulating effect of methylene blue and the influence of pH on the pentose phosphate pathway.

Blood↗
PubMed1976

Microcalorimetric measurements of heat production in human erythrocytes. III. Influence of pH, temperature, glucose concentration, and storage conditions.

Heat production in human erythrocytes has been measured under different conditions of pH, glucose concentration, and temperature. Storage conditions have also been varied. The erythrocytes, which were from healthy subjects, were suspended either in autologous plasma or in phosphate buffer. The heat effect, P, was shown to increase linearly in the physiological pH range: 1.2% per 0.01 pH unit. Variation of the glucose concentration within a wide range, 3-32 mmol/1, did not affect the P value. The temperature coefficient for P was determined to be Q10 = 2.8 for the temperature range 32-42 degrees C. A constant energy of activation was found, 82.6 kJ/mol, for the temperature range 25-42 degrees C. When the erythrocytes were stored at 4 degrees C, P values (measured at 37 degrees C) increased initially by 6%/h. After 24 h of storage P was about 50% higher than the initial value. Determinations of glucose consumption were made in parallel with most of the calorimetric experiments.

Blood Glucose↗
PubMed1976

Microcalorimetric measurements of heat production in human erythrocytes. IV. Comparison between different calorimetric techniques, suspension media, and preparation methods.

Heat production in human erythrocytes from healthy subjects has been measured under different experimental conditions. Simultaneous measurements were made on the same samples using different types of microcalorimeters: a static ampoule calorimeter, an air perfusion calorimeter, and a flow calorimeter. Obtained heat effect values for specified standard conditions, P degrees, were within uncertainty limits the same for the different calorimeters. Cells were suspended either in autologous plasma or in a phosphate buffer. P degrees values for buffer suspensions were significantly higher than those for plasma suspensions. Erythrocyte samples prepared by the column adsorption technique gave higher P degrees values than those obtained by a conventional centrifugation procedure.

Blood Preservation↗
PubMed1976

Microcalorimetric measurements of heat production in human erythrocytes. II. Hyperthyroid patients before, during and after treatment.

Heat production has been measured in erythrocytes of 17 hyperthyroid patients both before treatment and when the patients had become clinically euthyroid. The decrease in heat effect during treatment was significant. The initial mean value was significantly higher than the corresponding value for normal subjects. A good correlation was found between heat effect values and the clinical condition. Measurement of heat production in erythrocytes can provide useful information about the peripheral effect of thyroid hormones.

Buffers↗