User interface paradigms for patient-specific surgical planning: lessons learned over a decade of research.

This paper covers work in virtual reality-based, patient-specific surgical planning over the past decade. It aims to comprehensively examine the user interface paradigms and system designs during that period of time and to objectively analyze their effectiveness for the task. The goal is to provide useful feedback on these interface and implementation paradigms to aid other researchers in this field. First, specialized systems for specific clinical use were produced with a limited set of visualization tools. Later, through collaboration with NASA, an immersive virtual environment was created to produce high-fidelity images for surgical simulation, but it underestimated the importance of collaboration. The next system, a networked, distributed virtual environment, provided immersion and collaboration, but the immersive paradigm was found to be of a disadvantage and the uniqueness of the framework unwieldy. A virtual model, workbench-style display was then created using a commercial package, but limitations of each were soon apparent. Finally, a specialized display, with an integrated visualization and simulation system is described and evaluated. Lessons learned include: surgical planning is an abstract process unlike surgical simulation; collaboration is important, as is stereo visualization; and that high-resolution preoperative images from standard viewpoints are desirable, but interaction is truly the key to planning.     

Death anxiety in patients with epilepsy.

PURPOSE: Whereas the relationship between epilepsy and anxiety has received much attention, less is known about the relationship between death anxiety and this disorder. The objective of this study was to assess death anxiety among epileptic patients who attended the outpatient neurology clinic at the Salmaniya Medical Complex, Kingdom of Bahrain. METHODS: Ninety-two patients (48 males and 44 females) completed a death anxiety scale. The scale items were adopted from already published surveys and adjusted to suit epilepsy patients. RESULTS: Results showed that the mean death anxiety score was moderate (2.75+/-1.35), with 26.09% of patients reporting high levels of death anxiety. Period of illness and educational level were significant predictors of death anxiety. Female patients, generalized type of epilepsy, the short duration of the illness and low level of education were associated with higher death anxiety scores. CONCLUSION: This study highlights the need for developing treatment strategies, counseling therapies and social support for people with epilepsy to decrease their death anxiety and improve their quality of life.     

The interaction of parafluorohexahydrosiladiphenidol at muscarinic receptors in vitro

1. The antagonistic actions of parafluorohexahydrosiladiphenidol (pFHHSiD) at muscarinic receptors has been studied in cardiac muscle, smooth muscle and cell culture preparations. In this paper, the classification scheme of Doods et al. (1987) is employed. This scheme is based upon differential affinities of muscarinic antagonists. pFHHSiD exhibited high pA2 values at M3 receptors mediating contractions of guinea-pig ileum and oesophageal muscularis mucosae (7.8 and 8.2 respectively) whereas low values were determined at M2 receptors mediating negative inotropic responses in guinea-pig atria (6.0). Intermediate pA2 values were determined at M1 receptors mediating contractions of the canine femoral and saphenous veins. 2. The pA2 values of pFHHSiD at receptors mediating endothelial-dependent relaxation of rat aortic rings, rabbit jugular vein and canine femoral artery (7.6-7.9) were similar to those determined on the ileum. However, the pA2 values of pFHHSiD at receptors mediating contractions of the guinea-pig trachea (7.1), which has been previously shown to possess M3 receptors, were different from those determined in the ileum. 3. The similarity in pA2 values of pFHHSiD between the M3 receptors in guinea-pig ileum and the receptors mediating endothelial-dependent relaxations provide further evidence for the role of M3 receptors in this vascular response. Taken together, pA2 values for pFHHSiD range from 7.1 to 8.2, depending upon the M3 preparation used. The selectivity of the compound therefore for the M3 versus the M2 muscarinic receptor ranged from 13 to 163 fold.(ABSTRACT TRUNCATED AT 250 WORDS)     

Lack of effect of a single dose of hydrocortisone on serotonin(1A) receptors in recovered depressed patients measured by positron emission tomography with [11C]WAY-100635.

BACKGROUND: Elevated cortisol levels might account for the reduction in central serotonin 1A (5-hydroxytryptamine [5-HT](1A)) receptor binding and function observed in patients with major depression. We tested this hypothesis by studying the effect of acute administration of hydrocortisone on 5-HT(1A) receptor binding potential (BP) in subjects recovered from depression. METHODS: We studied 14 subjects (8 male, 6 female) who had recovered from at least two episodes of major depression and had been euthymic and drug free for at least 6 months. Serotonin 1A receptor BP was measured by [(11)C]WAY-100635 in conjunction with positron emission tomography. Subjects were tested on two occasions in a double-blind, random-order, crossover design after administration of either hydrocortisone (100 mg orally) or placebo 12 hours previously. Positron emission tomography scans were analyzed with a region of interest analysis. RESULTS: Hydrocortisone treatment did not decrease 5-HT(1A) receptor BP either in the hippocampus, which was our a priori hypothesis, or in other cortical 5-HT(1A) regions; however, female subjects had a higher 5-HT(1A) receptor BP in certain brain areas compared with male subjects. CONCLUSIONS: These data are consistent with an earlier study in healthy volunteers and do not support the proposal that decreased 5-HT(1A) receptor BP in patients with acute major depression is a consequence of cortisol hypersecretion.