Thermal behavior of HeLa and KB cells in suspension and attached to glass

The Kinetics of Thermal Injury in Human Renal Carcinoma Cells

In this study, the thermal injury behavior of both suspended and attached SN12 human renal carcinoma cells (RCC) under thermal therapy conditions (i.e., heating cells to elevated temperature for seconds to minutes) was investigated using a non-isothermal method. This non-isothermal method entailed heating the cells using a programmable heating stage from room temperature at 130 degrees C min(-1) to various peak temperatures from 45 to 70 degrees C, held for 0-10 min, and then cooling down to room temperature at 65 degrees C min(-1). It was found that the suspended SN12 cells are more heat susceptible than attached ones. The non-isothermal portions (i.e., the heat-up and cool-down portions) of the thermal histories were found to be able to cause significant injury (> 10%) in both suspended and attached SN12 cells when the peak temperature is above 60 degrees C. Therefore, a non-isothermal method, which accounts for both the isothermal and non-isothermal portions of the thermal histories, was used to extract the kinetic parameters (i.e., the activation energy and frequency factor) in the Arrhenius injury model for SN12 cells. Furthermore, these results suggest that this non-isothermal method can be used to extract kinetic parameters from in vivo heating studies using minimally invasive surgical probes, where it is very difficult to get a thermal history in tissue with a dominant isothermal portion.

Microcalorimetric measurements of tissue cells in vitro

A culture flask was designed for the microcalorimetric measurements of tissue cells by an MS 80 standard calvet microcalorimeter. Tissue cells cultured in this flask behaved in the same manner as in the common culture flask used in cytobiological studies. The thermograms of human adenocarcinoma gastric cells (SGc 7901) and HeLa cells were obtained. The heat output power of SGc 7901 cells continuously increased for 70 h with an initial cell number of 3.0 X 10(5). The thermogram was reproducible under strictly controlled conditions. The relationship between the heat output power and the number of SGc 7901 cells within 48 h was obtained. The heat output power was 40 pW/cell to 49 pW/cell when the cell number was in the range 4.5 X 10(5) to 10.4 X 10(5). It was 62.3 +/- 2.9 pW/cell for HeLa cells when the cell number was 6 X 10(5).

Heat evolution of cultured human keratinocytes

The heat production of normal and transformed human epidermal keratinocytes precultured in Petriperm tissue culture dishes was measured calorimetrically. For this purpose, the membrane at the bottom of the culture dish was cut out aseptically and put into a microcalorimeter vessel with the cell layer inwards. A continuous heat output of (83 +/- 12) pW/cell was measured for normal keratinocytes from a confluent primary culture. A value of (134 +/- 35) pW/cell was obtained when the transformed keratinocyte line SV-K14 was used. The method described in this paper is simple, leads to reproducible results, and can be easily adapted to the calorimetric study of other mammalian cells in vitro.

Calorimetric techniques for metabolic studies of cells and organisms under normal conditions and stress

When cells are subjected to stress, an early result is a shift in type and rate of metabolism to reflect their new conditions. The availability of metabolites, their endogenous vs exogenous origins, and the rates at which they can be used, besides availability of oxygen, dictate cell and tissue response. Measurement of heat output in such a response is a means for monitoring cells and tissues. Differential heat conduction calorimeters are reviewed to provide a listing of instrument parameters important in optimum practical use. Data obtained with one cell system, mammalian sperm, are presented to provide an example of how the combination of calorimetry and carbon balance, plus calculation from thermodynamic constants, permit an assessment of the importance of endogenous metabolism to total cellular metabolism.

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.