An optical coherence tomography and endothelial shear stress study of a novel bioresorbable bypass graft

Endothelial shear stress (ESS) plays a key role in the clinical outcomes in native and stented segments; however, their implications in bypass grafts and especially in a synthetic biorestorative coronary artery bypass graft are yet unclear. This report aims to examine the interplay between ESS and the morphological alterations of a biorestorative coronary bypass graft in an animal model. Computational fluid dynamics (CFD) simulation derived from the fusion of angiography and optical coherence tomography (OCT) imaging was used to reconstruct data on the luminal anatomy of a bioresorbable coronary bypass graft with an endoluminal "flap" identified during OCT acquisition. The "flap" compromised the smooth lumen surface and considerably disturbed the local flow, leading to abnormally low ESS and high oscillatory shear stress (OSI) in the vicinity of the "flap". In the presence of the catheter, the flow is more stable (median OSI 0.02384 versus 0.02635, p < 0.0001; maximum OSI 0.4612 versus 0.4837). Conversely, OSI increased as the catheter was withdrawn which can potentially cause back-and-forth motions of the "flap", triggering tissue fatigue failure. CFD analysis in this report provided sophisticated physiological information that complements the anatomic assessment from imaging enabling a complete understanding of biorestorative graft pathophysiology

Current Performance and On-Going Improvements of the 8.2 m Subaru Telescope

An overview of the current status of the 8.2 m Subaru Telescope constructed and operated at Mauna Kea, Hawaii, by the National Astronomical Observatory of Japan is presented. The basic design concept and the verified performance of the telescope system are described. Also given are the status of the instrument package offered to the astronomical community, the status of operation, and some of the future plans. The status of the telescope reported in a number of SPIE papers as of the summer of 2002 are incorporated with some updates included as of 2004 February. However, readers are encouraged to check the most updated status of the telescope through the home page, http://subarutelescope.org/index.html, and/or the direct contact with the observatory staff.Comment: 18 pages (17 pages in published version), 29 figures (GIF format), This is the version before the galley proo

THERMOREGULATORY RESPONSES OF THE INITIAL STAGE OF BICYCLING IN A HEAT ENVIRONMENT

The purpose of this study is to determine the progress of whole body sweating rate (SR) in the initial stage of moderate work in two hot environments, and to relate the SR to the body temperature attained. Four healthy males, 28 to 31 years of age, performed leg exercise of 40% V^^・O_2max with a Monark bicycle ergometer set up on a platform scale (Potter bed balance). All the experiments were carried out in a climatic chamber at ambient temperature (Ta) of 30゜C or 40゜C (relative humidity, 45%) in winter season following body heating for 30 min at a room temperature of 30゜C. Skin sweating was monitored by the bed balance with automatic weight change indicator throughout the experimental period. Rectal (Tre) and 7 skin temperatures were measured every minute by a thermistor and thermocouples, respectively. Oxygen consumption was determined before and during the work by the Douglas bag method. Heart rate was recorded by electrocardiography throughout the experiment. At Ta 40゜C, the SR increased as soon as the work started, whereas at Ta 30゜C it took a few minutes. The mean SR during the work at Ta 40゜C was significantly higher than that at Ta 30゜C. The level of mean skin temperature (T^^-sk) was higher at Ta 40゜C (35゜C) than Ta 30゜C (33゜C), and Tre was approximately 37.3゜C at Ta 30゜C and 40゜C. The changes in the Tre and T^^-sk were similar in two different conditions. The negative correlations were found between the SR and the T^^-sk during the work. The regression line was significantly different at Ta 30゜C and 40゜C. The T^^-sk decreased in proportion to increase of the SR. Moreover, there was a good correlation between the SR and heart rate during the work in both environments. Heat production stood at the same level in two different thermal conditions. The present study suggests that the body core temperature in working men is maintained at least constant level, since the evaporation in the initial stage of the work is largely stimulated, and the reduction of skin temperature may be caused by other factors than the evaporation

Skin Surface Temperatures during Submaximal Cycling Observed by Color Thermography

Colored thermograpy was used to observe skin temperature distribution over the upper half of body during bicycle exercise in cool environment. Skin temperature began to fall immediately at the onset of exercise. Increased work loads produced a proportional reduction in skin temperature