The New England journal of medicine
-
Comparative Study
Difference between endothelium-dependent relaxation in arterial and in venous coronary bypass grafts.
Both the internal mammary artery and the saphenous vein are used to construct coronary-artery bypass grafts. We hypothesized that the release or production of endothelium-derived relaxing factor, which regulates blood flow and inhibits platelet function, may differ in venous and arterial grafts. We therefore studied endothelium-dependent relaxation in internal mammary arteries, internal mammary veins, and saphenous veins obtained from 58 patients undergoing coronary bypass surgery. ⋯ Endothelium-independent relaxation in response to sodium nitroprusside was similar in arteries and veins. We conclude that endothelium-dependent relaxation is greater in the mammary artery than in the saphenous vein. The possibility that this contributes to the higher patency rate among arterial grafts than among venous grafts will require further study.
-
Indomethacin is a potent agent in the treatment of premature labor, but its use has been limited because of concern about its constrictive effects on the fetal ductus arteriosus. To study these effects we used serial fetal echocardiography in 13 pregnant women in premature labor who received indomethacin according to three different dose schedules, ranging from 100 to 175 mg per day, for a maximum of 72 hours. The gestational ages of the fetuses ranged from 26.5 to 31.0 weeks. ⋯ In all seven fetuses affected, ductal constriction had resolved by the time they were restudied 24 hours after the discontinuation of indomethacin. Persistent fetal circulation was not detected in any of the 11 neonates studied after delivery. Indomethacin used to treat premature labor appears to cause transient constriction of the ductus arteriosus in some fetuses, even after short-term use.
-
Among 141 consecutive patients with neuro-psychiatric abnormalities due to cobalamin deficiency, we found that 40 (28 percent) had no anemia or macrocytosis. The hematocrit was normal in 34, the mean cell volume was normal in 25, and both tests were normal in 19. Characteristic features in such patients included paresthesia, sensory loss, ataxia, dementia, and psychiatric disorders; longstanding neurologic symptoms without anemia; normal white-cell and platelet counts and serum bilirubin and lactate dehydrogenase levels; and markedly elevated serum concentrations of methylmalonic acid and total homocysteine. ⋯ Except for one patient who died during the first week of treatment, every patient in this group benefited from cobalamin therapy. Responses included improvement in neuropsychiatric abnormalities (39 of 39), improvement (often within the normal range) in one or more hematologic findings (36 of 39), and a decrease of more than 50 percent in levels of serum methylmalonic acid, total homocysteine, or both (31 of 31). We conclude that neuropsychiatric disorders due to cobalamin deficiency occur commonly in the absence of anemia or an elevated mean cell volume and that measurements of serum methylmalonic acid and total homocysteine both before and after treatment are useful in the diagnosis of these patients.