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'Z-RNA'--a left-handed RNA double helix.

In contrast to double-stranded DNA, there has so far been little evidence that double-stranded RNA can undergo major conformational transitions. We have investigated the conformation in different conditions of the double-stranded RNA molecule poly(G-C).poly(G-C), by NMR, circular dichroism and absorbance spectroscopy. We report here evidence obtained by these different spectroscopic techniques that poly(G-C).poly(G-C) undergoes a transition from the A-form to a left-handed Z-form in conditions of high ionic strength and at temperatures above 35 degrees C. This conformational transition may be of relevance to the biological situations in which double-stranded RNA occurs, such as in ribosomes and in some viruses.

Circular Dichroism↗

PubMedDate not supplied

[Improved oxygenation with nitric oxide treatment for hepatopulmonary syndrome after a liver transplant].

A 37-year-old man with cirrhosis of the liver hospitalized for orthotopic liver transplant (OLT) was found to have hepatopulmonary syndrome (HPS) during routine presurgical assessment. No problems with oxygenation developed during surgery. In the early recovery period, however, hypoxemia was observed to be uncorrected in spite of gradual normalization of liver function tests. OLT sometimes corrects HPS and, therefore, hypoxemia. However, significant decreases in oxygenation during recovery have been reported to affect patient morbidity and mortality. We therefore started low-dose nitric oxide (NO) inhalation once other possible causes of hypoxemia had been ruled out. Oxygenation improved, allowing tubes to be removed. Seven months after OLT, home oxygen therapy was still required to treat basal hypoxemia. HPS persisted, as confirmed by echocardiogram. Inhaled NO contributed to maintenance of adequate oxygenation during the early postoperative period, as essential for long-term survival in patients with HPS who undergo OLT.

Adult↗