RESUMEN
The possibility of introducing various functionalities on peptides with relative ease allows them to be used for molecular applications. However, oligopeptides prepared entirely from proteinogenic amino acids seldom assemble as ordered structures on surfaces. Therefore, sidechain modifications of peptides that can increase the intermolecular interactions without altering the constitution of a given peptide become an attractive route to self-assembling them on surfaces. We find that replacing phenylalanine residues with unusual amino acids that have phenylcarbonyl sidechains in oligopeptides increases the formation of ordered self-assembly on a highly ordered pyrolytic graphite surface. Peptides containing the modified amino acids provided extended long-range ordered assemblies, while the analogous peptides containing phenylalanine residues failed to form long-range assemblies. X-ray crystallographic analysis of the bulk structures of these peptides and the analogous peptides containing phenylalanine residues reveal that such modifications do not alter the secondary structure in crystals. It also reveals that the secondary hydrogen bonding interaction through phenylcarbonyl sidechains facilitates extended growth of the peptides on graphite.
RESUMEN
Background: Commonly used prognostic scores for acute on-chronic liver failure (ACLF) have complex calculations. We tried to compare the simple counting of numbers and types of organ dysfunction to these scores, to predict mortality in ACLF patients. Methods: In this prospective cohort study, ACLF patients diagnosed on the basis of Asia Pacific Association for Study of the Liver (APASL) definition were included. Severity scores were calculated. Prognostic factors for outcome were analysed. A new score, the Number of Organ Dysfunctions in Acute-on-Chronic Liver Failure (NOD-ACLF) score was developed. Results: Among 80 ACLF patients, 74 (92.5%) were male, and 6 were female (7.5%). The mean age was 41.0±10.7 (18-70) years. Profile of acute insult was; alcohol 48 (60%), sepsis 30 (37.5%), variceal bleeding 22 (27.5%), viral 8 (10%), and drug-induced 3 (3.8%). Profiles of chronic insults were alcohol 61 (76.3%), viral 20 (25%), autoimmune 3 (3.8%), and non-alcoholic steatohepatitis 2 (2.5%). Thirty-eight (47.5%) were discharged, and 42 (52.5%) expired. The mean number of organ dysfunction (NOD-ACLF score) was ->4.5, simple organ failure count (SOFC) score was >2.5, APASL ACLF Research Consortium score was >11.5, Model for End-Stage Liver Disease-Lactate (MELD-LA) score was >21.5, and presence of cardiovascular and respiratory dysfunctions were significantly associated with mortality. NOD-ACLF and SOFC scores had the highest area under the receiver operating characteristic to predict mortality among all these. Conclusion: The NOD-ACLF score is easy to calculate bedside and is a good predictor of mortality in ACLF patients performing similar or better to other scores.
RESUMEN
Mono-carboxyl-functionalized azobenzene and arylazopyrazole have been employed for electron-induced and photoinduced switching under ambient conditions. The microscopic structure and the switching behavior is understood using scanning tunneling microscopy. The carboxyl functional group in these molecules offers low threshold energy for the electron-induced reversible switching compared with nonfunctionalized azobenzene. The low threshold is understood using charged intermediate states during the switching. A selectivity has been observed for the photoinduced switching. Because of strong hydrogen bonding, only the free phenyl groups in the molecules change their configuration.
