A heat transfer model of thermal balloon endometrial ablation.

A heat transfer model was developed for thermal balloon endometrial ablation treatment for menorrhagia. The model includes heat conduction through the uterus wall, cooling due to blood perfusion through the uterine tissue and the contribution of metabolic heat generation. A parameter sensitivity study indicated that metabolic heat generation had a minimal effect, but model predictions were sensitive to blood perfusion rate. However, within the range of expected perfusion rates, the model calculates damage depths (3-6 mm) close to the range for effective treatment. Using a blood perfusion rate of 0.0028 m(3)t m(-3)b s(-1), the predicted burn depth (4 mm) correlated well with experimental measurements (4.2 +/- 0.6 mm) reported elsewhere for a treatment temperature of 92 degrees C and time of 6 mins (Neuwirth, R. S. et al. The endometrial ablator: A new instrument. Obstet. Gynecol. 83:792-796, 1994). If no vaporization of water in the tissue occurs, the model predicts that the same burn depth of 4 mm can be obtained with increased treatment temperature (130 degrees C) and shorter treatment time (1.4 min). Steeper temperature profiles through the uterine wall suggest that, in the absence of other changes due to higher temperatures, the deeper layers of the myometrium and the serosa would be protected from thermal damage when using higher treatment temperatures for a shorter duration. However, if vaporization occurs at 105 degrees C, the model predicts little benefit in using treatment temperatures above 120 degrees C up to 160 degrees C. For further validation of the model, in vivo studies using the high temperature treatments are needed to measure temperature profiles through the uterine wall, blood perfusion rates, and the other effects of temperature on uterine tissue.

PACSIN, a brain protein that is upregulated upon differentiation into neuronal cells.

To identify genes that are differentially expressed during self-repair processes in mouse brain, we screened a subtracted cDNA library enriched for brain-specific clones. One of these clones, H74, detected a 4.4-kb mRNA predominantly expressed in brain and dorsal root ganglia neurons. Expression increased continuously during the lifespan and the state of differentiation, but decreased after entorhinal-cortex lesion. A full-length cDNA clone was isolated from a cerebellum cDNA library and characterized. Sequence analysis and database search revealed high sequence similarity to FAP52, a protein expressed in focal-adhesion contacts, and uncharacterized Echinococcus and Caenorhabditis elegans gene products. Furthermore, peptide sequences derived from human cDNA fragments showed up to 65% sequence identity at the amino acid level. The presence of a C-terminal src homology 3 (SH3) domain and its phosphorylation by casein kinase 2 (CK2) and protein kinase C (PKC) imply a role in signaling. Here we demonstrate that the gene encodes a phosphoprotein, referred to as PACSIN, with a restricted spatial and temporal expression pattern.