High resolution imaging of intracellular oxygen concentration by phosphorescence lifetime.

Optical methods using phosphorescence quenching by oxygen are suitable for sequential monitoring and non-invasive measurements for oxygen concentration (OC) imaging within cells. Phosphorescence intensity measurement is widely used with phosphorescent dyes. These dyes are ubiquitously but heterogeneously distributed inside the whole cell. The distribution of phosphorescent dye is a major disadvantage in phosphorescence intensity measurement. We established OC imaging system for a single cell using phosphorescence lifetime and a laser scanning confocal microscope. This system had improved spatial resolution and reduced the measurement time with the high repetition rate of the laser. By the combination of ubiquitously distributed phosphorescent dye with this lifetime imaging microscope, we can visualize the OC inside the whole cell and spheroid. This system uses reversible phosphorescence quenching by oxygen, so it can measure successive OC changes from normoxia to anoxia. Lower regions of OC inside the cell colocalized with mitochondria. The time-dependent OC change in an insulin-producing cell line MIN6 by the glucose stimulation was successfully visualized. Assessing the detailed distribution and dynamics of OC inside cells achieved by the presented system will be useful to understanding a physiological and pathological oxygen metabolism.

Alternative approach for aortic valve replacement: in mediastinal deviation after right lobectomy.

A 71-year-old man on hemodialysis and with a history of right lobectomy was referred for aortic valve replacement. Chest computed tomography revealed counterclockwise rotation of the heart through its longitudinal axis.We approached the aortic valve through median sternotomy. Accordingly, we transected the sternum at the level of the 3rd intercostal space and extended the skin incision approximately 2 inches perpendicular to the midline. After partial transection of the sternum, 3 spreaders were placed: the 1st, in the upper sternum; the 2nd, in the lower sternum; and the 3rd, between the ribs. These devices yielded excellent exposure of the ascending aorta. In addition, the relatively central shift of the ascending aorta contributed to the exposure of the right atrium and the right upper pulmonary vein. Subsequently, aortic valve replacement was performed in the usual fashion, and the patient experienced no postoperative respiratory complications. Aortic valve surgery with T-shaped sternotomy and without thoracotomy is an alternative technique in a patient who has a secondary deviation after lobectomy.

[Clinical analysis of precaution against atrial fibrillation following cardiac surgery: landiolol or amiodarone?].

Atrial fibrillation following cardiac surgery remains as a most common complication. Tachycardia with atrial fibrillation just after the operation could lead to cardiac deterioration. Although we have to control tachycardia, we often have great difficulties in managing these arrhythmias. Many reports have showed landiolol, ultra short-acting beta1 blocker, and amiodarone were effective against postoperative atrial fibrillation. However there has been no report on comparison between these 2 drugs. As excessively sympathetic activity might cause atrial fibrillation, landiolol was introduced into our therapy concomitant with the sedative. Our investigation confirmed that both landiolol and amiodarone were effective in preventing atrial fibrillation, and that the timing of transition from intravenous administration to oral intake was acceptable. When landiolol was administered, enough attention should be paid to the patients whose left ventricular function was low. The patients in whom atrial fibrillation occurred under landiolol therapy showed tendency of lower heart rate in comparison with the patients under amiodarone therapy.