Novel benzenesulfonate scaffolds with a high anticancer activity and G2/M cell cycle arrest

Sulfonates, unlike their derivatives, sulphonamides, have rarely been investigated for their anticancer activity. Unlike the well-known sulphonamides, esters are mainly used as conve-nient intermediates in a synthesis. Here, we present the first in-depth investigation of quinazoline sulfonates. A small series of derivatives were synthesized and tested for their anticancer activity. Based on their structural similarity, these compounds resemble tyrosine kinase inhibitors and the p53 reactivator CP-31398. Their biological activity profile, however, was more related to sulphonamides because there was a strong cell cycle arrest in the G2/M phase. Further investigation revealed a multitargeted mechanism of the action that corresponded to the p53 protein status in the cell. Al-though the compounds expressed a high submicromolar activity against leukemia and colon cancers, pancreatic cancer and glioblastoma were also susceptible. Apoptosis and autophagy were confirmed as the cell death modes that corresponded with the inhibition of metabolic activity and the activation of the p53-dependent and p53-independent pathways. Namely, there was a strong activation of the p62 protein and GADD44. Other proteins such as cdc2 were also expressed at a higher level. More-over, the classical caspase-dependent pathway in leukemia was observed at a lower concentration, which again confirmed a multitargeted mechanism. It can therefore be concluded that the sulfonates of quinazolines can be regarded as promising scaffolds for developing anticancer agents

Nanomechanical studies of the interaction of antimicrobial peptides with bacterial cells

© 2016 Dr. Anna MularskiAntimicrobial peptides (AMPs) are promising therapeutic alternatives to conventional antibiotics. Many AMPs are membrane-active but their mode of action in killing bacteria or in inhibiting their growth remains elusive. Recent studies indicate the mechanism of action depends on peptide structure and lipid components of the bacterial cell membrane. To date, most of these studies have been conducted with synthetic membrane systems, which neglect the possible role of bacterial surface structures in these interactions. Here, we use atomic force microscopy (AFM) to study the interactions of three different AMPs on living Klebsiella pneumoniae bacterial cells. K. pneumoniae are recognized as a serious cause of nosocomial infections and a source of shared antimicrobial resistance. Typically, K. pneumoniae assemble a polysaccharide layer (known as the capsule) on the outside of the cell envelope, taking the form of a hydrated polyelectrolyte network that can grow up to several hundred nanometers thick, and can provide protection from environmental stresses, including desiccation, detergents, antibiotics and host immune defenses. It also plays a role in bacterial adherence to surfaces (such as medical devices) through the formation of biofilms. In situ biophysical measurements were performed to understand how the antimicrobial modulate various biophysical behaviours of individual bacteria, including the turgor pressure, cell wall elasticity, and bacterial capsule thickness and organisation. Firstly, the interactions of a melittin-derived lytic peptide with live K. pneumoniae cells were studied revealing that exposure to the peptide had a significant effect on the turgor pressure and Young’s modulus of the cell. The turgor pressure increased upon peptide addition followed by a later decrease, suggesting that cell lysis occurred and pressure was lost through destruction of the cell envelope. The Young’s modulus also increased, indicating that interaction with the peptide increased the rigidity of the cell wall. The bacterial capsule appeared unaffected by exposure to the peptide and microbiological assays determined that the presence of the capsule conferred no advantage to the wild-type over capsule deficient cells when exposed to the peptide. These findings suggest that even though the long-range electrostatic attraction between the peptide and capsule may first attract the peptide to the bacterial cell, it is the drive of the peptide to associate with the membrane that dominates once the peptide approaches the bacterial outer envelope. The methodology developed was then applied to study the interaction of the polypeptide antibiotic, colistin sulfate, with both wild-type and colistin-resistant K. pneumoniae. The capsular polysaccharides of wild-type cells were rearranged after exposure to colistin, particularly at lysis inducing concentrations, where the capsule appears to unravel. Colistin resistant mutant cells did not display the same behaviour. Microbiological assays showed that the presence of the capsule confers no advantage for wild-type over the capsule deficient cells. Genetic sequencing of the colistin resistant mutant showed that it’s ten-fold resistance to colistin is conferred by a reduction in net negative charge of the lipopolysaccharide molecules embedded in the outer membrane. Negative charge reduction could hinder the initial electrostatic binding of colistin to the outer membrane and the displacement of the divalent cations that function to bridge adjacent LPS molecules throughout the capsular polysaccharide network. Retention of the cross-linking divalent cations may explain why capsule thickness measurements did not increase in the colistin-resistant strain after colistin exposure. These results contrast with those for other K. pneumoniae strains that suggest the capsule confers colistin resistance. Finally, the interaction of caerin 1.1 with K. pneumoniae cells was studied. Caerin is a peptide similar in structure and size to melittin. As with the melittin derived peptide, the capsule of K. pneumoniae AJ218 was unchanged by exposure to caerin, indicating once again that the ionic interaction of the positively charged peptide with the negatively charged capsular polysaccharide is not a critical component of AMP interaction with K. pneumoniae AJ218 cells, the presence of a capsule conferring no advantage to wild-type over capsule-deficient cells when exposed to the AMP caerin. Time-resolved AFM images revealed that the antimicrobial peptide (AMP) caerin 1.1 caused localised defects in the cell walls of lysed Klebsiella pneumoniae cells, corroborating a pore-forming mechanism of action. The defects continued to grow during the AFM experiment, in corroboration with large holes that were visualised by scanning electron microscopy. Defects in cytoplasmic membranes were visualised by cryo-EM using the same peptide concentration as in the AFM experiments. At three times the minimum inhibitory concentration of caerin, ‘pores’ were apparent in the outer membrane. The three studies presented here demonstrate that AFM measurements can be used to track changes in bacterial cells as they lyse due to peptide interaction. In all three studies, the presence capsular polysaccharides conferred no advantage to wild-type over capsule-deficient K. pneumoniae, suggesting ionic interaction between the peptides and bacteria-bound capsular polysaccharides is not a key component of the interaction with the K. pneumoniae AJ218. Finally, AFM and cryo-EM data have shown these three peptides operate via different mechanisms of action with K. pneumoniae

Telemedycyna w położnictwie na przykładzie urządzenia mobilnego do zdalnego wykonywania badań kardiotokograficznych (KTG)

Wstęp. Urządzenia do samodzielnego, zdalnego wykonywania badań kardiotokograficznych (KTG) w warunkach domowych coraz silniej ugruntowują swoją pozycję we współczesnym położnictwie. Ich niewielkie rozmiary, prosty interfejs aplikacji oraz duża dokładność zapisów sprawiają, że kobiety i lekarze coraz częściej decydują się korzystać z nich w trakcie ciąży, a w szczególności gdy istnieje podwyższone ryzyko położnicze. Materiał i metody. W pracy przedstawiono doświadczenia własne oparte na materiale 94 kobiet, u których wykonano zapis kardiotokograficzny, wykorzystując Telemedyczny system KTG Sigmafon Carebits w Klinice Perinatologii Uniwersytetu Medycznego w Łodzi (60 pacjentek) oraz Klinice Położnictwa i Perinatologii Uniwersytet Jagielloński, Collegium Medicum w Krakowie (34 pacjentki). Dodatkowo dokonano oceny wybranych parametrów technicznych używanego aparatu KTG. Ponadto każda z ciężarnych, po wykonanym badaniu kardiotokograficznym,wypełniła standaryzowany kwestionariusz ankiety, przedstawiając swoją opinię na temat urządzenia. Wyniki. Podsumowując, zapisy KTG wykonane telemedycznym aparatem KTG System Sigmafon nie wykazały istotnych różnic pod względem jakości i rzetelności w porównaniu zapisami KTG wykonanymi przy użyciu najlepszych dostępnych w klinice stacjonarnych aparatów KTG. Urządzenie wykorzystane w badaniu dostarczyło zapisy o bardzo wysokim standardzie. Średnia utrata sygnału FHR z 94 badań wyniosła 5,58%. Telemedyczny aparat KTG został bardzo dobrze przyjęty przez ciężarne, a sama technika wykonania badania nie sprawiała większych trudności. Wnioski. Po opracowaniu odpowiedniej strategii, telemonitoring w ciążach podwyższonego ryzyka, może przyczynić się do ograniczenia zbędnych hospitalizacji, a co za tym idzie niepotrzebnych kosztów jak i również stresów dla ciężarnych, wynikających z pobytu na oddziale położniczym

Exploiting Symmetry in Variational Quantum Machine Learning

Variational quantum machine learning is an extensively studied application of near-term quantum computers. The success of variational quantum learning models crucially depends on finding a suitable parametrization of the model that encodes an inductive bias relevant to the learning task. However, precious little is known about guiding principles for the construction of suitable parametrizations. In this work, we holistically explore when and how symmetries of the learning problem can be exploited to construct quantum learning models with outcomes invariant under the symmetry of the learning task. Building on tools from representation theory, we show how a standard gateset can be transformed into an equivariant gateset that respects the symmetries of the problem at hand through a process of gate symmetrization. We benchmark the proposed methods on two toy problems that feature a nontrivial symmetry and observe a substantial increase in generalization performance. As our tools can also be applied in a straightforward way to other variational problems with symmetric structure, we show how equivariant gatesets can be used in variational quantum eigensolvers

Arpin is critical for phagocytosis in macrophages and is targeted by human rhinovirus

International audienc

Atomic Force Microscopy Reveals the Mechanobiology of Lytic Peptide Action on Bacteria

Increasing rates of antimicrobial-resistant medically important bacteria require the development of new, effective therapeutics, of which antimicrobial peptides (AMPs) are among the promising candidates. Many AMPs are membrane-active, but their mode of action in killing bacteria or in inhibiting their growth remains elusive. This study used atomic force microscopy (AFM) to probe the mechanobiology of a model AMP (a derivative of melittin) on living <i>Klebsiella pneumoniae</i> bacterial cells. We performed <i>in situ</i> biophysical measurements to understand how the melittin peptide modulates various biophysical behaviors of individual bacteria, including the turgor pressure, cell wall elasticity, and bacterial capsule thickness and organization. Exposure of <i>K. pneumoniae</i> to the peptide had a significant effect on the turgor pressure and Young’s modulus of the cell wall. The turgor pressure increased upon peptide addition followed by a later decrease, suggesting that cell lysis occurred and pressure was lost through destruction of the cell envelope. The Young’s modulus also increased, indicating that interaction with the peptide increased the rigidity of the cell wall. The bacterial capsule did not prevent cell lysis by the peptide, and surprisingly, the capsule appeared unaffected by exposure to the peptide, as capsule thickness and inferred organization were within the control limits, determined by mechanical measurements. These data show that AFM measurements may provide valuable insights into the physical events that precede bacterial lysis by AMPs