Effectiveness of Malodor-Reducing Ostomy Pouch Additives: An Assessment of Odor Intensity, Hedonic Tone, and Odor Character.

Background Ostomy pouch odor can have a negative impact on the quality of life of people living with a stoma. This study assessed the effectiveness of malodor-reducing ostomy pouch additives under simulated conditions. Methodology The following six commercially available products with different odor control technologies plus a control were assessed: soyethyl morpholinium ethosulphate, zinc ricinoleate (ZnR), ZnR with orange terpenes (ZnR-Orange), a proprietary copper-based deodorant, a proprietary ion mix deodorant, and a terpene blend (TB). Each was added to an ostomy pouch with skatole (a substitute for human fecal odor). Professional olfactometrists rated odors according to intensity, hedonic tone (pleasantness), and character. Results The TB and ZnR-Orange had very weak (<1.0) malodor intensity, with mean (standard deviation [SD]) ratings of 0.6 (1.1) and 0.9 (0.9), respectively. All other products (2.7-3.0) and control (3.7) were statistically higher (stronger intensity) compared with the TB(p < 0.001). The mean (SD) hedonic tone for the TB was 0.8 (1.7) (considered slightly pleasant); all other products (-0.8 to 0.1) and control (-0.9) were statistically lower (p < 0.001). Odor character profiles were broadly comparable, but products with scent additives (TB and ZnR-Orange) were predominantly associated with fragrances. Conclusions This information may help nurses and other healthcare providers when educating ostomates about their options. Other factors such as application mode and recommended dosage may also influence the choice of product. Future research on real-world populations (i.e., ostomates), as well as assessment of lubrication properties, is warranted.

Enzyme-cargo encapsulation peptides bind between tessellating tiles of the bacterial microcompartment shell.

Bacterial microcompartments are prokaryotic organelles comprising encapsulated enzymes within a thin protein shell. They facilitate metabolic processing including propanediol, choline, glycerol, and ethanolamine utilization, and they accelerate carbon fixation in cyanobacteria. Enzymes targeted to the inside of the microcompartment frequently possess a cargo-encapsulation peptide, but the site to which the peptide binds is unclear. We provide evidence that the encapsulation peptides bind to the hydrophobic groove formed between tessellating subunits of the shell proteins. In silico docking studies provide a compelling model of peptide binding to this prominent hydrophobic groove. This result is consistent with the now widely accepted view that the convex side of the shell oligomers faces the lumen of the microcompartment. The binding of the encapsulation peptide to the groove between tessellating shell protein tiles explains why it has been difficult to define the peptide binding site using other methods, provides a mechanism by which encapsulation-peptide bearing enzymes can promote shell assembly, and explains how the presence of cargo affects the size and shape of the bacterial microcompartment. This knowledge may be exploited in engineering microcompartments or disease prevention by hampering cargo encapsulation.

Control and regulation of S-Adenosylmethionine biosynthesis by the regulatory ß subunit and quinolone-based compounds.

Methylation is an underpinning process of life and provides control for biological processes such as DNA synthesis, cell growth, and apoptosis. Methionine adenosyltransferases (MAT) produce the cellular methyl donor, S-Adenosylmethionine (SAMe). Dysregulation of SAMe level is a relevant event in many diseases, including cancers such as hepatocellular carcinoma and colon cancer. In addition, mutation of Arg264 in MATα1 causes isolated persistent hypermethioninemia, which is characterized by low activity of the enzyme in liver and high level of plasma methionine. In mammals, MATα1/α2 and MATßV1/V2 are the catalytic and the major form of regulatory subunits, respectively. A gating loop comprising residues 113-131 is located beside the active site of catalytic subunits (MATα1/α2) and provides controlled access to the active site. Here, we provide evidence of how the gating loop facilitates the catalysis and define some of the key elements that control the catalytic efficiency. Mutation of several residues of MATα2 including Gln113, Ser114, and Arg264 lead to partial or total loss of enzymatic activity, demonstrating their critical role in catalysis. The enzymatic activity of the mutated enzymes is restored to varying degrees upon complex formation with MATßV1 or MATßV2, endorsing its role as an allosteric regulator of MATα2 in response to the levels of methionine or SAMe. Finally, the protein-protein interacting surface formed in MATα2:MATß complexes is explored to demonstrate that several quinolone-based compounds modulate the activity of MATα2 and its mutants, providing a rational for chemical design/intervention responsive to the level of SAMe in the cellular environment. ENZYMES: Methionine adenosyltransferase (EC.2.5.1.6). DATABASE: Structural data are available in the RCSB PDB database under the PDB ID 6FBN (Q113A), 6FBP (S114A: P221 21 ), 6FBO (S114A: I222), 6FCB (P115G), 6FCD (R264A), 6FAJ (wtMATα2: apo), 6G6R (wtMATα2: holo).