Silastic tubes are used as training material for performing microvascular anastomoses. However, silastic texture differs from that of actual blood vessels. In the present work, we evaluate the use of preserved rat arterial segments for training in microvascular anastomoses. One-centimeter-long rat arterial segments were obtained from femoral, carotid, and abdominal arteries, preserved in cold saline solution, and frozen. Trainees performed microvascular anastomoses using the aforementioned material and answered questions about texture, consistency, and wall resistance to the needle, comparing preserved arterial wall and silastic tubes. They were also asked whether the arterial pedicles had a consistency and texture similar to normal vessels, and if they were a more reliable method for practicing microsurgery techniques than synthetic materials. They preferred frozen arterial pedicles over silastic tubes. We conclude that arterial cadaveric segments are a suitable biologic material for microsurgical training. Since they can be obtained from other experiments, this is an effective way to reduce the number of animals bred and sacrificed for teaching purposes.
The compliance of the total respiratory system (CRS) was determined by the occlusion technique during expiration in 19 preterm newborns (NB) over 31 weeks of gestational age (mean, 34 +/- 1.5 SD) and in 20 full-term NB. Postnatal age ranged from 1 to 28 days. No sedation was used during the test. In absolute terms, CRS was significantly greater (P less than 0.01) in full-term than in preterm NB (3.17 +/- 0.71 ml/cm H2O vs 2.37 +/- 0.81 ml/cm H2O). When normalized for body weight, length cubed, [corrected] body surface area, and the Quetelet index (body weight/length squared) [corrected], CRS was similar in preterm and full-term NB. These results suggest that, normalized for biometric data, passive elastic properties of the total respiratory system are similar in full-term and preterm NB, at least in the gestation age range studied.
The objective of this paper was to determine the physiological values of urea nitrogen and creatinine in tears, and to compare the results with those obtained from serum. Thirty healthy thoroughbred horses were included in the study. Tear fluid samples were obtained using a glass capillary tube placed in lower conjunctival cul-de-sac. Blood samples were taken from the jugular vein. Tear and serum urea nitrogen and creatinine levels were quantitatively analyzed by an enzymatic colorimetric method. Urea nitrogen values were 4.22+/-1.84 mmol/l in tears and 4.44+/-1.78 mmol/l in serum, whereas creatinine values in tears were 14.14+/-7.74 micromol/l and in serum 147.63+/-12.17 micromol/l. Statistical analysis confirmed a significant correlation between serum and tear urea levels (P<0001). However, there was no significant correlation between blood and tear creatinine values. Mean value of creatinine obtained from tears was 9.6% of the mean value from serum. Urea nitrogen and creatinine levels can be measured in tears. A significant correlation was found between serum and tears urea levels. This finding may permit development of a new alternative laboratory diagnosis of uremia based on the content of urea in tears.
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