Dietary polyunsaturated fat decreases coronary artery atherosclerosis in a pediatric-aged population of African green monkeys

The hypothesis tested was that juvenile African green monkeys consuming diets enriched with n-6 polyunsaturated fat from birth until young adulthood would have significantly less coronary artery atherosclerosis than comparable animals consuming diets enriched with saturated fat. African green monkeys (Cercopithecus aethiops, n = 108) of both sexes were fed atherogenic diets (0.8 mg cholesterol/kcal) throughout their lives so that death at 16, 32, or 60 months of age permitted quantification of atherosclerosis. In the coronary arteries, the average intimal area increased significantly with age (P = .02), showing increases of 28-fold and sevenfold between 32 and 60 months in the saturated fat- and polyunsaturated fat-fed groups, respectively. Young adult male animals at 60 months of age were found to have significantly (P = .03) more coronary artery atherosclerosis than female animals. Animals fed polyunsaturated fat had significantly (P < or = .01) less coronary artery atherosclerosis. By 60 months of age in the animals consuming polyunsaturated fat, the average coronary artery intimal area was one fourth and the average size of the largest coronary intimal lesion was one fifth that in monkeys fed saturated fat. Low-density lipoprotein (LDL) cholesterol and LDL particle size were each found to be positively correlated with coronary artery atherosclerosis end points in both diet groups. In addition to the coronary arteries, atherosclerosis in the abdominal and thoracic aorta and carotid arteries was also evaluated; the coronary arteries were the only arterial system with significantly less atherosclerosis in the polyunsaturated fat group as measured by intimal area. However, evaluation of histological sections of abdominal aorta showed relatively more sterol clefts in the saturated fat-fed group, and more free cholesterol was measured, suggesting that lesions were more complicated in this group. These results show that dietary intervention early in life with n-6 polyunsaturated fat can be effective in decreasing the development of atherosclerosis, particularly in the coronary arteries of primates. This outcome supports the concept that dietary intervention beginning early in childhood can have beneficial effects on the coronary heart disease of later life.     

Evaluation of a breast biopsy phantom for learning freehand ultrasound-guided biopsy of the liver

RATIONALE AND OBJECTIVES: We evaluated whether a breast biopsy phantom device would aid in the development of skills in freehand ultrasound liver biopsy. METHODS: Three radiologists who were inexperienced in freehand biopsy of the liver were observed. Each radiologist was timed and scored during attempts to biopsy lesions created in a beef liver. The time required for biopsy and the success of each pass was recorded. A commercially available breast biopsy phantom was then used by each of these radiologists during two 20-min practice sessions. Posttraining testing on the beef liver was performed in the same manner as pretraining testing. RESULTS: Freehand biopsy practice using the breast biopsy phantom resulted in a reduction in the mean time required for biopsy from 32 to 17 sec. Each of the three subjects reduced the mean time required for successful biopsy after training using the breast biopsy phantom. The total number of lesions missed was reduced from 14 of 43 to 0 of 45. CONCLUSION: Practice using the ultrasound breast biopsy phantom improves performance in freehand ultrasound biopsy of the liver.     

Host factors that influence the duration of menstrual bleeding

We assessed the association between weight, exercise, and stress and the duration of menstrual bleeding in a 1-year prospective menstrual diary study of 166 college first-year women, age 17-19 years. Low weight-for-height increased expected bleed duration by 0.39 day. Dieting to lose weight reduced bleed length by 0.43 day. Women who did no moderate or hard exercise bled about a quarter of a day longer than women at the median level of physical activity.     

Test-retest reliability of high-frequency thresholds at bedside with sensorineural hearing-impaired listeners

Previous investigations have established the reliability of high-frequency thresholds performed in a sound suite using headphones. In addition, test-retest reliability of high-frequency thresholds in adults with normal hearing in a hospital room versus a sound-treated booth has also been established. The current study evaluated the test-retest reliability of thresholds in the 8000- to 18000-Hz range in 15 hearing-impaired adults (26 ears) with varying degrees of sensorineural hearing loss. A high-frequency audiometer and supra-aural earphones were used to measure thresholds in a typical hospital room. Results revealed no significant difference between repeated threshold measures. This study represents the third phase of an ongoing project to develop reliable bedside monitoring of patients undergoing ototoxic medical treatment.     

Effects of cold and warm blood cardioplegia assessed by myocardial pH and release of metabolic markers

The optimal temperature of blood cardioplegia remains controversial. Interstitial myocardial pH was monitored online with a probe that was inserted in the anterior wall of the left ventricle. Venous pH, lactate production, and creatine kinase and troponin T release were measured in coronary sinus blood obtained in 14 dogs after ischemic arrest periods of 5, 10, 20, and 40 minutes with warm (n = 7; mean myocardial temperature, 35 degrees +/- 2 degrees C) and cold (n = 7; mean myocardial temperature, 12 degrees +/- 1 degree C) blood cardioplegic protection. Blood cardioplegic solution was delivered at a rate of 100 mL/min during the 10 minutes between each ischemic arrest. The interstitial myocardial pH decreased significantly (p < 0.05) from 7.1 +/- 0.3 to 6.53 +/- 0.3 after ischemia in animals perfused with warm blood cardioplegia and from 7.04 +/- 0.3 to 6.64 +/- 0.1 in those receiving cold blood cardioplegic protection; however, the difference between the groups was not significant (p > 0.05). Lactate production and creatine kinase and troponin T release increased significantly after ischemia, but there was no difference in the changes between the warm and cold blood cardioplegia groups. In conclusion, ischemia caused significant changes in all variables measured, and these changes were directly proportional to the duration of ischemia. However, there was no significant difference (p > 0.05) in the myocardial metabolic changes between the warm and cold blood cardioplegia groups in terms of the duration of ischemic arrest studied.(ABSTRACT TRUNCATED AT 250 WORDS)     

Structural modeling of the pro-ocytocin-neurophysin precursor

The hormonal precursor pro-ocytocin-neurophysin is activated by selectivecleavage at Arg2-Ala13, producing mature ocytocin and neurophysin. Tounderstand the cleavage mechanism better, and in particular the recognitionof the cleavage site, it is necessary to characterize the three-dimensionalstructure of the precursor molecule. Here we combine a variety ofexperimental data with molecular modeling and dynamics calculations toderive possible precursor conformations. In the models obtained, theN-terminus of the precursor, corresponding to the ocytocin segment, ishydrogen bonded in a pocket of the neurophysin moiety in a similar mannerto a crystallographically obtained non-covalent complex between the twomolecules. The calculations suggest that although the ocytocin segment isrelatively flexible, it adopts a stable, broad loop structure in thevicinity of the cleavage region, which may constitute the structuralelement recognized by the cleaving enzyme. The calculations also suggest apossible widening of the distance between the two neurophysin domains inthe precursor relative to that in the non-covalent neurophysin- ocytocincomplex.