Improvement of patient localization repeatability using a light-section based optical surface guidance system in a pre-positioning procedure.

PURPOSE: Surface-guided radiotherapy is useful for the pre-positioning and monitoring of radiotherapy. The purpose of this study was to investigate the impact of surface guidance on the repeatability of patient localization and to estimate the specific point at which high positional errors occur. MATERIALS AND METHODS: Ten patients without the VOXELAN system (non-VXLN group) and 10 patients with the VOXELAN as the pre-positioning procedure (VXLN group) were included in this analysis. Twelve regions of interest (ROI) were defined in all the patients to verify any misalignment during radiotherapy. Thirteen ROIs were defined on the isocenter. RESULTS: Compared with the non-VXLN group, the translational positional errors of the VXLN group were the same for all the ROIs. The mean translational positional errors of the VXLN group in the longitudinal direction were approximately 0.1mm, and the standard deviation was the largest among the three directions in all the ROIs. The magnitude of the standard deviation in the non-VXLN group varied independently of the ROI and direction. The standard deviations of the VXLN group in the longitudinal direction were large in all the ROIs, while the standard deviations in the vertical and lateral directions were small. CONCLUSION: Pre-positioning with a surface guidance system reduced the body twist and rotation, which could not be corrected by image-guided radiotherapy alone. Since the VOXELAN can detect positioning errors quickly and without additional radiation exposure to the patient, it can be used as a tool for pre-positioning in radiotherapy.

Resistance to acidic and alkaline environments in the endodontic pathogen Enterococcus faecalis.

BACKGROUND/AIMS: This study aimed to investigate the biochemical mechanisms employed by the endodontic pathogen Enterococcus faecalis to confer acid- and alkali-resistance and to compare these with the mechanisms of representative oral streptococci. METHODS: E. faecalis JCM8728, Streptococcus mutans NCTC10449 and Streptococcus sanguinis ATCC10556 were used to assess both acid- and alkali-resistance by examining: (i) growth in complex media; (ii) stability of intracellular pH (pH(in)); (iii) cell durability to leakage of preloaded BCECF (2',7'-bis-(2-carboxyethyl)-5,6-carboxy-fluorescein); and (iv) cell permeability to SYTOX-Green. RESULTS: Growth was initiated by E. faecalis at pH 4.0-11.0, by S. mutans at pH 4.0-9.0 and by S. sanguinis at pH 5.0-9.0. The pH(in) was similar to the extracellular pH in S. mutans and S. sanguinis at pH 5-10, while the pH(in) of E. faecalis was maintained at approximately 7.5-8.5 when extracellular pH was 7.5-10 and was maintained at levels equivalent to the extracellular pH when pH < 7.5. Cell membranes of E. faecalis were resistant to BCECF leakage when extracellular pH was 2.5-12 and to SYTOX-Green permeability at pH 4-10. The cell membrane durability to extracellular pH in E. faecalis was higher than that observed in the Streptococcus strains. CONCLUSION: Compared to S. mutans, E. faecalis was found to be equally resistant to acid and more resistant to alkalis. The results suggest that pH-resistance in E. faecalis is attributed to membrane durability against acid and alkali, in addition to cell membrane-bound proton-transport systems. These characteristics may account for why E. faecalis is frequently isolated from acidic caries lesions and from persistently infected root canals where calcium hydroxide medication is ineffective.

[The left ventricle in chronic cor plumonale (author's transl)]. / Der linke Ventrikel bei chronischem Cor pulmonale

The volume of both ventricles was estimated in 25 hearts with chronic cor pulmonale. Also, the weight of the left ventricle, including the whole septum and the free part of the right ventricle, was determined to be 100 g. Distinct hypertrophy of the right ventricular part of the septum could be demonstrated in all cases. A weight increase of the left ventricle, including the whole septum, is frequently caused by the hypertrophic ventricular part of the septum. Th relative weight of the right ventricular portion )calculated according to Muller's method) was subtracted from the weight of the left ventricle plus the whole septum. After this weight correction, a hypertropyh of the left ventricle could only be demonstrated in cases with hypertension or renal arterio= and arteriolosclerosis. In one case of left ventricular hypertrophy, hypertension could not be ruled out. In most of the cases a distinct dilation of the left ventricle could be found. The highest degrees of dilation were found in patients with brohchiectases of the lungs. Our results indicate that the structural dialation of the left ventricle may be due to an increased shunt-volume by bronchopulmonary anastomoses.