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The purpose of this study was to compare core temperature measurements obtained from the $\rm CorTemp\sp{tm}$ ingestible capsule with those obtained simultaneously from rectal and esophageal probes in order to determine whether the capsule could be considered a suitable replacement for either of the other two methods. Comparisons were made in 20 subjects during rest, exercise (60 min of cycling at 50% HRR), and recovery on two occasions, spaced 16 hours apart. / Bland-Altman plots indicated that levels of agreement between capsules and esophageal and rectal probes exceeded the pre-determined level of acceptability $({\pm}0.5\sp\circ\rm C)$ at both +1 hr and +16 hrs for all three test conditions (rest, exercise, and recovery). During exercise, limits of agreement for the capsule v esophageal comparison extended from ${-}0.73\sp\circ$ to ${+}0.71\sp\circ\rm C$ at +1 hr, and from ${-}0.86\sp\circ$ to ${+}1.14\sp\circ\rm C$ at +16 hrs. For the capsule v rectal comparisons, limits extended from ${-}0.36\sp\circ$ to ${+}0.72\sp\circ\rm C$ at +1 hr and from ${-}0.41\sp\circ$ to ${+}0.91\sp\circ\rm C$ at +16 hrs. / The lack of acceptable agreement was due to the combination of bias, or mean differences between the methods, and to excessive variability among the differences between the methods. Of these two factors, the excessive variability contributed more to the lack of agreement than did the mean differences between methods. Causes for the excessive variability appear to be related to a lack of repeatability among each of the devices individually, to different rates of change in core temperature at the different sites, and to the mobility of the capsules within the gastrointestinal tract. / Within the scope and limitations of this study, it was concluded that the $\rm CorTemp\sp{tm}$ ingestible capsule remains unproven as a suitable replacement for rectal or esophageal probes for the measurement of core temperature. Although the capsules can accurately reflect temperatures in the controlled environment of a waterbath, once situated within the human gastrointestinal tract an unacceptable level of agreement with rectal and esophageal probes was observed. / Source: Dissertation Abstracts International, Volume: 55-09, Section: B, page: 3756. / Major Professor: Robert J. Moffatt. / Thesis (Ph.D.)--The Florida State University, 1994.

The adaptation of bone to mechanical loading is very poorly understood at the molecular genetic level. Little is known of gene expression in bone following mechanical stimulation primarily because of a lack of in vivo data. While the calcified extracellular matrix provides bone with its mechanical strength, it also makes the analysis of genetic information difficult. A new method has been developed which can extract high quality RNA from intact bone. This new technique enables the use of the Sprague Dawley rat to study the in vivo regulation of skeletal gene expression The tibia of fifteen skeletally mature female rats were subjected to either a dynamic four point bending stimulation or parathyroid hormone (PTH) stimulation. The animals were sacrificed within a twenty-four hour period following stimulation. The RNA within the tibia was extracted with the novel method and examined by Northern blot analysis. The constitutive expression of mRNA transcripts coding for transforming growth factor-beta 1 (TGF-$\beta$1) and $\alpha$-1 collagen I (COL I $\alpha$-1) were observed. Densitometric examinations demonstrated that over the first 24 hours, there was down regulation of TGF-$\beta$1 mRNA following mechanical stimulation (p = 0. 005). The TGF-$\beta$1 mRNA was maximally depressed at 1 hour and increased gradually over the remaining twenty-four hours. PTH seemed to cause a similar down regulation of TGF-$\beta$1 mRNA but no significance was reached (p = 0.097) To better quantify transcriptional differences, an internal control gene, ribosomal protein S3 (RPS3), was selected. RPS3 is transcribed at a steady state rate and can therefore be used to normalize other mRNA levels. With this technique, a six fold increase in COL I $\alpha$-1 mRNA transcripts was observed twelve hours following stimulation with PTH (p =.006) The constitutive expression of TGF-$\beta$1 and COL I $\alpha$-1 in bone in vivo are significant new pieces of molecular genetic information. TGF-$\beta$1 and COL I $\alpha$-1 are factors known to be involved in the process of bone formation. The fact that they are always present indicates that their in vivo regulated expression may prove helpful in our understanding of the mechanisms of human bone formation / acase@tulane.edu

Methods to estimate the surface Laplacian from scalp potentials are developed for improving spatial resolution in electroencephalography. This dissertation addresses two issues involved with estimating the surface Laplacian: (1) head geometry models; and (2) interpolation of the surface potential distribution. Theoretical and human data were used to validate the methods developed The surface Laplacian is defined as the second spatial derivative of the scalp potential, a direct measure of the radial current density flowing from the brain through the skull to the scalp. Previous research has shown the surface Laplacian to be a better estimator of underlying brain electrical activity. However, no apparent comprehensive research had been performed to develop and validate optimal methods for estimating the surface Laplacian, 'optimal' being defined in the practical sense as suitable interpolation methods based on present knowledge of head geometry and volume conduction properties Quantitative measurements of the upper surface of the human head show an ellipsoid surface to be an excellent geometric model of the head. RMS errors and maximum residuals between the digitized head and best fit ellipsoid are below the standard scalp electrode size of one cm. A three-variable natural cubic spline was found to be the apparent best means of obtaining an accurate estimate of the scalp surface potential. Other interpolation methods and splines have inherent characteristics which can result in unrealistic functions, or are limited to one surface geometry. The surface Laplacian estimate has been derived for the sphere and ellipsoid for the case of three-variable spline interpolation The algorithms were validated with the three-concentric sphere model of the head and two types of evoked potential tests, somatosensory and auditory evoked response (cognitive) potentials. The spline generated surface Laplacian topographic maps of theoretical data provided better spatial resolution than potential based maps. Topographic maps of human data were consistently repeatable between trials and subjects. The results agree with published literature and, additionally, suggest new regions of brain electrical activity not previously cited in the published literature. The results suggest that the surface Laplacian methods developed here provide accurate estimates of brain electrical activity / acase@tulane.edu

Extracellular compound action potential recordings revealed that transmission of physiological rates (1-5 Hz) of preganglionic nerve impulse activity through superior cervical ganglia (SCG) is enhanced in spontaneously hypertensive rats (SHR), the animal model of genetic hypertension used in these studies. Further studies indicated that these same ganglia have a diminished ability to transmit high frequencies ($>$70 Hz) of nerve activity Intracellular EPSP and EPSC recordings from single SCG neurons suggest that the enhanced impulse transmission observed in these ganglia results from an increase in transmitter release by the preganglionic nerve terminals innervating postganglionic SCG neurons. This increased transmitter release results in an elevated EPSP amplitude thereby increasing the efficacy of impulse transmission in SHR sympathetic ganglia. The increased transmitter release also depletes a similarly sized immediately releasable transmitter store to a greater extent in the hypertensive rats when compared to normotensive controls. The enhanced transmitter depletion diminishes the amount of short-term facilitation and enhances synaptic depression, limiting the ability of SHR preganglionic neurons to increase transmitter release during repetitive stimuli. These difference are hypothesized to play a role in the previously mentioned relative inability of SHR ganglia to transmit high frequency nerve impulse activity Whole-cell voltage-clamp recordings from acutely isolated SCG neurons revealed that postsynaptic membrane sensitivity to ACh, and the time course of ACh action are the same in SHR and normotensive controls, suggesting that postganglionic alterations do not play a role in the altered impulse transmission observed in SHR sympathetic ganglia The enhanced ability of SHR sympathetic ganglia to transmit physiological rates of preganglionic nerve activity would result in a greater amplification of preganglionic nerve activity in SHR ganglia, when compared to normotensive controls. This amplification of sympathetic nerve activity would directly contribute to the maintenance of hypertension in this animal model, and may be representative of cellular alteration(s) that are responsible for the enhanced sympathetic nerve activity observed in the SHR. Therefore, these studies further implicate an exaggerated sympathetic nerve activity in the pathogenesis of hypertension in the SHR model and reveal that an alteration of synaptic transmission could underlie the increased nerve activity / acase@tulane.edu