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Biomedical subjects

L H Gerig

Publications and source records attributed to L H Gerig.

6 recordsLinked to original sources
PubMed1992

The clinical use of thermocouple thermometry.

The development of a clinical thermometry system entails solving both clinical and technical problems. A thermometry system will, in general, be comprised of a temperature transducing element, a mechanism for interrogating the transducer temperature, and a means of interpreting, reporting and recording the measured temperature. Thermocouples are thermometers which report their own temperature, while the parameter of interest is the temperature of the medium. The two key questions which arise are then: (1) is the thermometer correctly reporting its own temperature, and (2) what is the relationship between the medium temperature and the thermometer temperature? In this work some of the important parameters influencing the temperature of the thermometer and the thermal relationship between the thermometer and the medium are investigated.

Body Temperature↗
PubMed1989

A comparison of heat and radiation sensitivity of three human glioma cell lines.

Three human glioma cell lines were tested for radiation and hyperthermia sensitivity and compared to the responses of a normal human fibroblast cell line. The radiation response of the glioma cell lines exhibited a large shoulder on the radiation survival curve indicating radioresistance when compared to the more radiosensitive fibroblast cell line. The hyperthermia response for the glioma cell lines was qualitatively similar to responses reported for other cell lines. When compared to normal human fibroblasts the glioma cells were found to be more sensitive to hyperthermia than the normal fibroblasts indicating hyperthermia may be a promising method or adjunct to radiotherapy in the treatment of resistant glioma cells or tumors. The results also show that both the radiation and thermal response is influenced by cell culture conditions and growth status. Two of the cell lines grown to confluency and treated in confluency showed an increased radiation resistance at low doses and the cell lines showed decreased resistance at high doses compared to cells plated to confluency (see Methods and Materials). An increased thermal resistance, especially at the lower heating temperatures, was also observed for cells grown to confluency. Measurements of residual glucose in the culture medium at the time of irradiation was about the same for the two culture methods (55%-65%). Cell cycle analysis showed that the differences were not related to changes in cell cycle distribution.

Adaptation, Physiological↗
PubMed1986

Multivolumetric analysis of CT scans on patients with glioma.

Brain tumor volumes in patients having multimodal therapy for cerebral gliomas were calculated using graphic methods and Simpsonian integration. Volume assessment calculations differed from the clinical assessment of the patient significantly in some cases. These calculations may be useful in on-going tumor therapy and should be used as a true scientific end point in brain tumor treatment protocols.

Brain Neoplasms↗
PubMedDate not supplied

On the spatial resolution of clinical thermometers.

In this work the spatial resolution of type T (copper-Constantan) and type K (Chromel-Alumel) multipoint thermocouple thermometers was investigated. For clinical use, thermocouples are usually inserted within catheters to provide easy access, reproducibility, and a sterile environment. The effect of several types of catheter on the ability of these thermometers to accurately resolve thermal gradients was studied. The influence of the number of wire pairs within the multipoint thermometer was also investigated. A mathematical model has been developed to determine the spatial resolving power of these thermometers. Results indicate that type K thermocouples are generally superior to type T and the use of catheters plays a significant role in spatial resolution. Moreover, the use of mineral oil as a thermal coupling agent between the catheter and the thermometer was also found to have some effect.

Humans↗
PubMedDate not supplied

Hyperthermia enhancement of radiation response and inhibition of recovery from radiation damage in human glioma cells.

Three human glioma cell lines were tested for the effectiveness of hyperthermia and thermal radiosensitization. Thermal sensitization was evaluated from the perspective of increased radiosensitivity as well as inhibition of recovery from radiation damage. The three glioma cell lines tested showed large shoulders on the radiation survival curve and a large capacity for recovery of potentially lethal radiation damage. Hyperthermia caused radiosensitization in all three cell lines, which was primarily characterized by the reduction of the survival curve shoulder with moderate decreases in the survival curve slope. The radiosensitization was dependent on the time and temperature of the hyperthermia treatment. At 45 degree C for 60 min the shoulder of the radiation survival curve could be completely eliminated and the degree of enhanced cell killing at the 2 Gy level ranged from factors of 10 to 20 under the various conditions. When hyperthermia was given to cells which were irradiated and then plated immediately, or delayed for 8 h before plating to allow recovery, hyperthermia was found to cause radiosensitization under both conditions. In addition, when the hyperthermia dose was increased the difference between the immediate plating and the delayed plating survival curve decreased and for 45 degrees C for 60 min this difference was completely eliminated, concomitantly with the elimination of the survival curve shoulder. These data indicate that hyperthermia may play a role in radiosensitization for the treatment of human glioma.

Brain Neoplasms↗