Detection of glucosamine as a marker for Aspergillus niger: a potential screening method for fungal infections.

Several species of fungus from the genus Aspergillus are implicated in pulmonary infections in immunocompromised patients. Broad screening methods for fungal infections are desirable, as cultures require a considerable amount of time to provide results. Herein, we developed degradation and detection methods to produce and detect D-glucosamine (GlcN) from Aspergillus niger, a species of filamentous fungus. Ultimately, these techniques hold the potential to contribute to the diagnosis of pulmonary fungal infections in immunocompromised patients. In the following studies, we produced GlcN from fungal-derived chitin to serve as a marker for Aspergillus niger. To accomplish this, A. niger cells were lysed and subjected to a hydrochloric acid degradation protocol. Products were isolated, reconstituted in aqueous solutions, and analyzed using hydrophilic interaction liquid chromatography (HILIC) in tandem with electrospray ionization time-of-flight mass spectrometry. Our results indicated that GlcN was produced from A. niger. To validate these results, products obtained via fungal degradation were compared to products obtained from the degradation of two chitin polymers. The observed retention times and mass spectral extractions provided a two-step validation confirming that GlcN was produced from fungal-derived chitin. Our studies qualitatively illustrate that GlcN can be produced from A. niger; applying these methods to a more diverse range of fungi offers the potential to render a broad screening method for fungal detection pertinent to diagnosis of fungal infections.

Identification of low molecular weight degradation products from chitin and chitosan by electrospray ionization time-of-flight mass spectrometry.

The beneficial effects provided by chitosan oligosaccharides (COS) make them of interest in medical research. The monomers that constitute COS confer distinct properties, so controlling COS composition during their production is significant. In this work, we degraded chitin and chitosan polymers and identified low molecular weight products such as COS that formed, using electrospray ionization time-of-flight mass spectrometry. Our results show that hydrochloric acid, hydrogen peroxide, and nitrous acid generate distinct products from chitin and chitosan. Hydrochloric acid degrades chitin and chitosan to produce glucosamine (GlcN) monomers and oligomers. Hydrogen peroxide degrades chitosan to produce GlcN and N-acetyl-d-glucosamine (GlcNAc) monomers and oligomers, and nitrous acid degrades chitosan to produce 2,5-anhydro- d-mannose. Our studies show that COS composition is dictated by both the degradation protocol and the starting polymer. Additionally, our results enable selection of degradation protocols based on their ability to degrade chitin and chitosan and facilitate the production of COS with desired compositions.

A Case Report of Adhesional Small Bowel Obstruction Caused by Extraintestinal Anisakiasis.

BACKGROUND: Small bowel obstruction (SBO) is a common diagnosis made in the emergency department (ED). We present a case with an unusual underlying cause of SBO: extraintestinal infection with an Anisakis roundworm. CASE REPORT: A healthy young woman with no prior abdominal surgery presented with epigastric abdominal pain, nausea, and anorexia 1 day after eating a raw oyster. Laboratory studies were significant for 14% eosinophilia. Initial abdominal computed tomography (CT) showed small bowel inflammation and small-volume ascites. After discharge home, she returned on day 14 of illness with a closed-loop SBO, to which she was predisposed by an adhesion formed in association with an eosinophilic abscess containing an Anisakis roundworm. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Anisakiasis is an uncommon cause of common symptoms with which patients may present to EDs. The diagnosis should be considered in patients presenting with abdominal pain and recent ingestion of raw seafood, with suspicion raised further by the presence of focal gastric or small bowel inflammation and ascites on abdominal CT. Extraintestinal anisakiasis can cause inflammation leading to intraabdominal adhesions, a sequela of which is small bowel obstruction. If suspicion for gastric or intestinal anisakiasis is high, treatment with endoscopic removal or albendazole may be initiated.

S-Nitrosoglutathione exhibits greater stability than S-nitroso-N-acetylpenicillamine under common laboratory conditions: A comparative stability study.

S-Nitrosothiols (RSNOs) such as S-nitrosoglutathione (GSNO) and S-nitroso-N-acetylpenicillamine (SNAP) are susceptible to decomposition by stimuli including heat, light, and trace metal ions. Using stepwise isothermal thermogravimetric analysis (TGA), we observed that NO-forming homolytic cleavage of the S-N bond occurs at 134.7 ±â€¯0.8 °C in GSNO and 132.8 ±â€¯0.9 °C in SNAP, contrasting with the value of 150 °C that has been previously reported for both RSNOs. Using mass spectrometry (MS), nuclear magnetic resonance (NMR), and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), we analyzed the decomposition products from TGA experiments. The organic product of GSNO decomposition was glutathione disulfide, while SNAP decomposed to form N-acetylpenicillamine disulfide as well as other products, including tri- and tetrasulfides. In addition, we assessed the relative solution stabilities of GSNO and SNAP under common laboratory conditions, which include variable temperature, pH, and light exposure with rigorous exclusion of trace metal ions by chelation. GSNO exhibited greater stability than SNAP over a 7-day period except in one instance. Both RSNOs demonstrated an inverse relationship between solution stability and temperature, with refrigeration considerably extending shelf life. A decrease in pH from 7.4 to 5.0 also enhanced the stability of both RSNOs. A further decrease in pH from 5.0 to 3.0 resulted in decreased stability for both RSNOs, and is notably the only occasion in which SNAP proved more stable than GSNO. After 1 h of exposure to overhead fluorescent lighting, both RSNOs displayed high susceptibility to light-induced decomposition. After 7 h, GSNO and SNAP decomposed 19.3 ±â€¯0.5% and 30 ±â€¯2%, respectively.

Nitric oxide generation from S-nitrosoglutathione: New activity of indium and a survey of metal ion effects.

S-Nitrosothiols (RSNOs) such as S-nitrosoglutathione (GSNO) are known to produce nitric oxide (NO) through thermal, photolytic, and metal ion-promoted pathways, which has led to their increasing use as exogenous sources of therapeutic NO. Despite the burgeoning NO release applications for RSNOs, their susceptibility to metal-promoted decomposition has rarely been examined in a uniform manner through the specific measurement of NO release. In this study, the ability of various transition and post-transition metal ions to promote NO release from GSNO was surveyed by chemiluminescence-based NO detection. Substantial NO formation (>10-fold increase relative to GSNO baseline) was detected after the addition of Cu2+, Au3+, Pd2+, Pt2+, and V3+. Modest increases were observed in the cases of Co2+, Hf4+, Fe2+, Fe3+, Mn2+, Hg2+, Ni2+, Ag+, Sn2+, and Zr4+, while no effect was evident for Al3+, Cr3+, Pb2+, Sc3+, and Zn2+. It was further observed that In+ compounds initiate the apparent NO-forming decomposition of GSNO, while In0 and In3+ are inactive, indicating that In+ exerts a previously unknown effect on GSNO.

Examining the effect of common nitrosating agents on chitosan using a glucosamine oligosaccharide model system.

Chitosan has received substantial attention as a biomaterial due to its unique properties. It has become increasingly common to derivatize chitosan to produce nitric oxide (NO)-releasing materials that exert various therapeutic effects through the action of NO. It is generally the case that these NO-releasing polymers are prepared by exposure to high-pressure NO or nitrosating agents like nitrous acid (HNO2) or alkyl nitrites (RONO). In our study, mass spectrometry and spectroscopic methods demonstrate that both monomeric and oligomeric glucosamine experience chemical alteration after exposure to HNO2-based nitrosating conditions from the literature. In polymeric chitosan, HNO2-based nitrosating conditions were found to induce degradation through the formation of 2,5-anhydro-d-mannose and oligosaccharides. In contrast, the RONO tert-butyl nitrite and high-pressure NO were not found to significantly degrade or otherwise alter the structure of glucosamine or its oligomers, supporting the suitability of these approaches.