3D Surface Measurement for Medical Application—Technical Comparison of Two Established Industrial Surface Scanning Systems

In 3D mapping of flexible surfaces (e.g. human faces) measurement errors due to movement or positioning occur. Aggravated by equipment- or researcher-caused mistakes considerable deviations can result. Therefore first the appliances' precision handling and reliability in clinical environment must be established. Aim of this study was to investigate accuracy and precision of two contact-free 3D measurement systems (white light vs. laser). Standard specimens of known diameter for sphere deviation, touch deviation and plane deviation were tested. Both systems are appropriate for medical application acquiring solid data (<mm). The more complex white-light system shows better accuracy at 0.2s measuring time. The laser system is superior concerning robustness, while accuracy is poorer and input time (1.5-2.5s) longer. Due to the clinical demand the white-light system is superior in a laboratory environment, while the laser system is easier to handle under non-laboratory condition

Swelling, Intracellular Acidosis, and Damage of Glial Cells

Cerebral ischemia and severe head injury among others are associated with a limited availability of oxygen, leading to cell catabolism as well as anaerobic glycolysis. Resulting metabolites, such as arachidonic- and lactic acid, can be expected to leak into perifocal brain areas, contributing there to cytotoxic swelling and damage of neurons and glia. Since elucidation of mechanisms underlying cell swelling and damage in the brain is difficult in vivo, respective investigations were carried out in vitro using suspended glial cells. Thereby, effects of arachidonic acid (AA) and of lactacidosis on glial cell volume, intraccHular pH (pH1), and cell damage were analyzed utilizing flow cytometry. AA led to an immediate, dose dependent swelling and intracellular acidosis of glial cells. A concentration of 0.1 mM increased cell volume to 110 % of control and decreased pH1 to 7.05. Whereas glial swelling was permanent, pH1 recovered to baseline after 90 min. Cell viability of 90 % remained unchanged after addition of AA up to 0.1 mM, while at 0.5 mM it was significantly decreasing. Glial swelling from AA was nearly completely inhibited by the aminosteroid U-74389F or by using a Na+-free suspension medium for the experiment. Acidification of the medium to pH 6.8 or A.2 led to a cell volume of 110 % or 120 % of control without affecting cell viability. The cells were not capable to defend their normal pH1 during lactacidosis of the suspension medium but became acidotic as well. Addition of amiloride or utilization of Na+-free medium inhibited cell swelling from lactacidosis, while intracellular acidosis was even more pronounced. The results indicate that AA as well as acidosis are potent mediators of glial swelling and damage at levels found under pathophysiological conditions in the brain in vivo. Whereas intracellular aciditication caused by AA was reversible, glial cells were unable to regulate their pH1 during maintenance of extracellular acidosis. Concerning the mechanisms of glial swelling by AA, the production of oxygen- and lipid radicals might play a major role in the swelling process. The results indicate a role of the Na+/H+-antiporter in acidosis-induced glial swelling, whereas the exchanger has a limited significance for maintenance of pH1. As seen, the final pathway of glial swelling from both, AA and lactacidosis, requires a net influx of Na+-ions, probably together with Cl -ions, and osmotically obliged water.link_to_subscribed_fulltex

3D surface measurement for medical application--technical comparison of two established industrial surface scanning systems

In 3D mapping of flexible surfaces (e.g. human faces) measurement errors due to movement or positioning occur. Aggravated by equipment- or researcher-caused mistakes considerable deviations can result. Therefore first the appliances' precision handling and reliability in clinical environment must be established. Aim of this study was to investigate accuracy and precision of two contact-free 3D measurement systems (white light vs. laser). Standard specimens of known diameter for sphere deviation, touch deviation and plane deviation were tested. Both systems are appropriate for medical application acquiring solid data (>mm). The more complex white-light system shows better accuracy at 0.2 s measuring time. The laser system is superior concerning robustness, while accuracy is poorer and input time (1.5-2.5 s) longer. Due to the clinical demand the white-light system is superior in a laboratory environment, while the laser system is easier to handle under non-laboratory conditions