Abstract: To determine if ordinary doses of nitrates produce a significant increase in methemoglobin, methemoglobin levels were measured in 59 randomly selected patients with coronary artery disease and unstable angina pectoris who were receiving organic nitrate therapy. Patients were taking isosorbide dinitrate, 2% nitroglycerin ointment, or a combination of the two. Patients were subdivided according to whether they were using one (group A) or more than one (group B) organic nitrate preparations. These results were compared with 17 control patients. Mean methemoglobin levels in group B were 1.78 ± 1.29%, and this differed significantly ( P < 0.05) from both group A mean methemoglobin, 1.13 ± 0.92%, and controls, 0.99 ± 0.55%. The proportion of patients with elevated methemoglobin concentration increased from the control to group A to group B. It is concluded that commonly used dosages of nitrates are capable of causing elevations of methemoglobin which are probably not of routine clinical significance. However, these elevations may be of import in certain patient populations such as those with coronary insufficiency or anemia.
A 32-year-old engineer presented for elective arthroscopy on a weekend. He was assessed pre-operatively and was noted to have a Mallampati 1 airway and was generally fit and well. He elected to receive a general anaesthetic. After induction with propofol, a size 5 laryngeal mask was placed uneventfully using the standard technique. The operative course was uneventful and, immediately after the surgery, the patient was comfortable and did not complain of difficulty swallowing or a sore throat. However, 2 days after the surgery, he telephoned the anaesthetic department complaining that he had a sore throat that had not improved over the weekend and that 'the floppy thing at the back of my throat has turned yellow!' Despite his graphic description and worries, he was not keen to brave the Seattle traffic and come to the department. Instead, he reasoned he could take some pictures with his newly acquired digital camera and e-mail them to us. After a few minutes, we received the fruits of his labours. It appeared from the pictures (Fig. 16) that he had an ischaemic uvular. Over the next few days (and a series of pictures) the uvular demarcated and separated. Uvular trauma has been reported after general anaesthesia with laryngeal masks [1]. The necrosis that our patient experienced presumably occurred as a result of compression of the uvular by the tip of the laryngeal mask being folded over, and remains an unusual complication. More unusual still was the method of diagnosis. Yet another useful use of e-mail!
We have studied how puroindoline-b (PINB) mutants bind to model eukaryotic membranes dependent on binary composition of anionic:zwitterionic phospholipids and the presence of cholesterol and sphingomyelin in the model membrane. We have found that the trends in lipid binding behavior are different for wild-type PINB compared to its naturally occurring PINB(Trp44Arg) mutant form and have seen evidence of protein-induced domain formation within the lipid layer structure. Results show that selective binding of antimicrobial peptides to different membrane types is as a result of differences in lipid composition and the arrangement of lipids within the membrane surface. However, membrane-binding behavior is not easily predicted; it is determined by net charge, hydrophobicity, and the amphiphilicity of the protein/peptide lipid-binding domain.
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