Butterfly in the Esophagus: A Case Report on a Rare Esophageal Manometry Catheter Malposition.

We report the case of a 75-year-old man who underwent high-resolution manometry (HRM) testing for solid food dysphagia after an unrevealing upper endoscopy and biopsies. A barium esophagogram confirmed nonspecific motility disorder. A subsequent HRM study was performed, but when all swallow studies were noted to fail, and the manometric images revealed a butterfly wings appearance, it was found that the manometry catheter was actually coiled and folded back cephalad. As there are only a few other case reports with similar presentations, we believe this case would serve as a good reminder for clinicians to practice caution when cannulating the manometry catheter.

Catalase as a sulfide-sulfur oxido-reductase: An ancient (and modern?) regulator of reactive sulfur species (RSS).

Catalase is well-known as an antioxidant dismutating H2O2 to O2 and H2O. However, catalases evolved when metabolism was largely sulfur-based, long before O2 and reactive oxygen species (ROS) became abundant, suggesting catalase metabolizes reactive sulfide species (RSS). Here we examine catalase metabolism of H2Sn, the sulfur analog of H2O2, hydrogen sulfide (H2S) and other sulfur-bearing molecules using H2S-specific amperometric electrodes and fluorophores to measure polysulfides (H2Sn; SSP4) and ROS (dichlorofluorescein, DCF). Catalase eliminated H2Sn, but did not anaerobically generate H2S, the expected product of dismutation. Instead, catalase concentration- and oxygen-dependently metabolized H2S and in so doing acted as a sulfide oxidase with a P50 of 20mmHg. H2O2 had little effect on catalase-mediated H2S metabolism but in the presence of the catalase inhibitor, sodium azide (Az), H2O2 rapidly and efficiently expedited H2S metabolism in both normoxia and hypoxia suggesting H2O2 is an effective electron acceptor in this reaction. Unexpectedly, catalase concentration-dependently generated H2S from dithiothreitol (DTT) in both normoxia and hypoxia, concomitantly oxidizing H2S in the presence of O2. H2S production from DTT was inhibited by carbon monoxide and augmented by NADPH suggesting that catalase heme-iron is the catalytic site and that NADPH provides reducing equivalents. Catalase also generated H2S from garlic oil, diallyltrisulfide, thioredoxin and sulfur dioxide, but not from sulfite, metabisulfite, carbonyl sulfide, cysteine, cystine, glutathione or oxidized glutathione. Oxidase activity was also present in catalase from Aspergillus niger. These results show that catalase can act as either a sulfide oxidase or sulfur reductase and they suggest that these activities likely played a prominent role in sulfur metabolism during evolution and may continue do so in modern cells as well. This also appears to be the first observation of catalase reductase activity independent of peroxide dismutation.

A case of mistaken identity: are reactive oxygen species actually reactive sulfide species?

Stepwise one-electron reduction of oxygen to water produces reactive oxygen species (ROS) that are chemically and biochemically similar to reactive sulfide species (RSS) derived from one-electron oxidations of hydrogen sulfide to elemental sulfur. Both ROS and RSS are endogenously generated and signal via protein thiols. Given the similarities between ROS and RSS, we wondered whether extant methods for measuring the former would also detect the latter. Here, we compared ROS to RSS sensitivity of five common ROS methods: redox-sensitive green fluorescent protein (roGFP), 2', 7'-dihydrodichlorofluorescein, MitoSox Red, Amplex Red, and amperometric electrodes. All methods detected RSS and were as, or more, sensitive to RSS than to ROS. roGFP, arguably the "gold standard" for ROS measurement, was more than 200-fold more sensitive to the mixed polysulfide H2Sn(n = 1-8) than to H2O2 These findings suggest that RSS may be far more prevalent in intracellular signaling than previously appreciated and that the contribution of ROS may be overestimated. This conclusion is further supported by the observation that estimated daily sulfur metabolism and ROS production are approximately equal and the fact that both RSS and antioxidant mechanisms have been present since the origin of life, nearly 4 billion years ago, long before the rise in environmental oxygen 600 million years ago. Although ROS are assumed to be the most biologically relevant oxidants, our results question this paradigm. We also anticipate our findings will direct attention toward development of novel and clinically relevant anti-(RSS)-oxidants.