Technical note: The use of a sonomicrometry system for monitoring uterine involution in postpartum dairy cows.

Sonomicrometry allows the measurement of the distance between 2 piezoelectric crystals and has been widely used to investigate the contractility of the heart and gastrointestinal tract. The objective of this study was to determine whether this method can be used to quantify the reduction in uterine size in cows postpartum. Seven healthy pluriparous Holstein Friesian cows (3.7±0.7 yr old, parity 2.4±0.5, mean±SD) were used. Three weeks before calving, 4 piezoelectric crystals were implanted via laparotomy in the myometrium of the greater curvature of the pregnant uterine horn in a longitudinal direction. Sonometric measurements were conducted daily from 2 d before parturition until 14 d after calving, followed by measurements every other day until d 28. Changes in the distance between neighboring crystals were presented as relative changes (%) from baseline values before parturition. The diameter of the previously pregnant uterine horn was measured using transrectal B-mode sonography from d 10 to 28 after calving. The cows were slaughtered 39±6 d postpartum and the uterus was evaluated for fixation of the crystals. The distances between neighboring crystals underwent changes with a reduction of greater than 50% until d 1 postpartum, but no further changes were recorded from d 1 to 7. In the second week, changes in all distances were affected by day postpartum. One distance was affected by day postpartum in wk 3 and 4. There was a positive correlation between the diameter of the previously pregnant horn and the distances between the crystals. Examination of the uterus after slaughter of the cows revealed that 8 crystals (29%) were no longer fixed in the myometrium. Seven of these (25%) could be evaluated completely or partially and 1 (4%) could not be analyzed. Sonomicrometry seems to be suitable for the objective measurement of reduction in uterine length in cows.

Uses and complications of isotretinoin therapy.

Isotretinoin (13-cis-retinoic acid) is a retinoid that has been used over the past 2 decades to treat a wide variety of dermatologic conditions, some with great success. Although it is beneficial in many skin conditions, the side effects and toxicities of oral retinoids require careful monitoring by experienced physicians. The clinical applications of oral retinoids continue to expand both within and beyond the field of dermatology.

Differential regulation of tyrosinase activity in skin of white and black individuals in vivo by topical retinoic acid.

Tyrosinase activity is a key determinant of melanin production in skin. Because retinoic acid regulates tyrosinase activity in melanoma cells, we analyzed modulation of pigmentation in vivo by retinoic acid. Black and white subjects were either not treated, or treated topically for 4 d under occlusion with vehicle, retinoic acid (0.1%), or the irritant sodium lauryl sulfate (2%). In untreated skin, tyrosinase activity and melanin content were significantly greater (2.3 times, and 3.2 times, respectively) in blacks versus whites. Four days of treatment with topical retinoic acid did not alter tyrosinase activity or melanin content in black skin. In contrast, retinoic acid treatment significantly induced (2.7 times, n = 8) tyrosinase activity, compared to vehicle treatment, in white skin. Melanin content, however, remained unchanged at 4 d. In separate experiments, tyrosinase activity in white subjects (n = 25) was increased 16% (p = 0.01) in sodium lauryl sulfate-treated skin, and 77% (p = 0.0005) in retinoic acid-treated skin, compared to vehicle-treated skin. The effect of retinoic acid on tyrosinase activity could be differentiated from non-specific irritation, because tyrosinase activity in retinoic acid-treated skin was significantly greater (52%, p = 0.004) than sodium lauryl sulfate-treated skin. Similar results were obtained with the dihydroxyphenylalanine reaction done on vehicle, sodium lauryl sulfate-, and retinoic acid-treated white skin. Northern analysis (n = 6) and semi-quantitative polymerase chain reaction (n = 6) demonstrated that retinoic acid treatment did not alter tyrosinase mRNA levels in white skin. Western analysis revealed that induction of tyrosinase activity by retinoic acid also was not associated with increased tyrosinase protein content (n = 9), indicating that regulation of tyrosinase activity by retinoic acid occurs through a post-translational mechanism. These data demonstrate that low tyrosinase activity in white skin in vivo is retinoic acid inducible and high tyrosinase activity in black skin in vivo is neither further induced nor reduced by retinoic acid.

Spontaneous rupture of the pulmonary artery.

A 45-year-old man presented with the sudden onset of diaphoresis, generalized weakness, and bilaterally achy arms. Physical examination revealed cyanosis of the head, neck, and upper chest with dyspnea and hypotension. He had distant heart sounds. An upright portable chest radiograph suggested widening of the mediastinum. A right arm venogram was consistent with extrinsic obstruction of the superior vena cava. A computed axial tomography scan demonstrated blood in the pericardium and indistinct widening of the pulmonary outflow tract. Autopsy revealed three tears of the pulmonary artery above the level of valve cusps, and thinning of the artery walls suggested cystic medial necrosis. These findings are suggestive of an acute spontaneous rupture of the pulmonary artery, possibly secondary to cystic medial necrosis.