Repositioning of Tamoxifen in Surface-Modified Nanocapsules as a Promising Oral Treatment for Visceral Leishmaniasis

Standards of care for human visceral leishmaniasis (VL) are based on drugs used parenterally, and oral treatment options are urgently needed. In the present study, a repurposing strategy was used associating tamoxifen (TMX) with polyethylene glycol-block-polylactide nanocapsules (NC) and its anti-leishmanial efficacy was reported in vivo. Stable surface modified-NC (5 mg/mL of TMX) exhibited 200 nm in size, +42 mV of zeta potential, and 98% encapsulation efficiency. Atomic force microscopy evidenced core-shell-NC. Treatment with TMX-NC reduced parasite-DNA quantified in liver and spleen compared to free-TMX; and provided a similar reduction of parasite burden compared with meglumine antimoniate in mice and hamster models. Image-guided biodistribution showed accumulation of NC in liver and spleen after 30 min post-administration. TMX-NC reduced the number of liver granulomas and restored the aspect of capsules and trabeculae in the spleen of infected animals. TMX-NC was tested for the first time against VL models, indicating a promising formulation for oral treatment.

Download Full-text

TheREnantiomer of the Antitubercular Drug PA-824 as a Potential Oral Treatment for Visceral Leishmaniasis

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00722-13 ◽

2013 ◽

Vol 57 (10) ◽

pp. 4699-4706 ◽

Cited By ~ 38

Author(s):

Stephen Patterson ◽

Susan Wyllie ◽

Laste Stojanovski ◽

Meghan R. Perry ◽

Frederick R. C. Simeons ◽

...

Keyword(s):

Clinical Trials ◽

Visceral Leishmaniasis ◽

Phase Ii ◽

Leishmania Donovani ◽

Oral Treatment ◽

Parasite Burden ◽

Content Type ◽

Phase Ii Clinical Trials

ABSTRACTThe novel nitroimidazopyran agent (S)-PA-824 has potent antibacterial activity againstMycobacterium tuberculosisin vitroandin vivoand is currently in phase II clinical trials for tuberculosis (TB). In contrast toM. tuberculosis, where (R)-PA-824 is inactive, we report here that both enantiomers of PA-824 show potent parasiticidal activity againstLeishmania donovani, the causative agent of visceral leishmaniasis (VL). In leishmania-infected macrophages, (R)-PA-824 is 6-fold more active than (S)-PA-824. Both des-nitro analogues are inactive, underlining the importance of the nitro group in the mechanism of action. Although thein vitroandin vivopharmacological profiles of the two enantiomers are similar, (R)-PA-824 is more efficacious in the murine model of VL, with >99% suppression of parasite burden when administered orally at 100 mg kg of body weight−1, twice daily for 5 days. InM. tuberculosis, (S)-PA-824 is a prodrug that is activated by a deazaflavin-dependent nitroreductase (Ddn), an enzyme which is absent inLeishmaniaspp. Unlike the case with nifurtimox and fexinidazole, transgenic parasites overexpressing the leishmania nitroreductase are not hypersensitive to either (R)-PA-824 or (S)-PA-824, indicating that this enzyme is not the primary target of these compounds. Drug combination studiesin vitroindicate that fexinidazole and (R)-PA-824 are additive whereas (S)-PA-824 and (R)-PA-824 show mild antagonistic behavior. Thus, (R)-PA-824 is a promising candidate for late lead optimization for VL and may have potential for future use in combination therapy with fexinidazole, currently in phase II clinical trials against VL.

Download Full-text

Rapid, Refined, and Robust Method for Expression, Purification, and Characterization of Recombinant Human Amyloid-beta M1-42

10.26434/chemrxiv.7725002.v1 ◽

2019 ◽

Author(s):

Priya Prakash ◽

Travis Lantz ◽

Krupal P. Jethava ◽

Gaurav Chopra

Keyword(s):

Amyloid Beta ◽

Western Blots ◽

Force Microscopy ◽

E Coli ◽

Atomic Force ◽

Set Up ◽

Short Time

Amyloid plaques found in the brains of Alzheimer’s disease (AD) patients primarily consists of amyloid beta 1-42 (Ab42). Commercially, Ab42 is synthetized using peptide synthesizers. We describe a robust methodology for expression of recombinant human Ab(M1-42) in Rosetta(DE3)pLysS and BL21(DE3)pLysS competent E. coli with refined and rapid analytical purification techniques. The peptide is isolated and purified from the transformed cells using an optimized set-up for reverse-phase HPLC protocol, using commonly available C18 columns, yielding high amounts of peptide (~15-20 mg per 1 L culture) in a short time. The recombinant Ab(M1-42) forms characteristic aggregates similar to synthetic Ab42 aggregates as verified by western blots and atomic force microscopy to warrant future biological use. Our rapid, refined, and robust technique to purify human Ab(M1-42) can be used to synthesize chemical probes for several downstream in vitro and in vivo assays to facilitate AD research.

Download Full-text

Biomechanics of Neutrophil Tethers

Life ◽

10.3390/life11060515 ◽

2021 ◽

Vol 11 (6) ◽

pp. 515

Author(s):

Andrea Cugno ◽

Alex Marki ◽

Klaus Ley

Keyword(s):

Cell Activation ◽

Optical Trap ◽

Biomechanical Properties ◽

Force Microscopy ◽

Advantages And Disadvantages ◽

Atomic Force ◽

Microfluidic Flow ◽

Biomembrane Force Probe ◽

Membrane Reservoir

Leukocytes, including neutrophils, which are propelled by blood flow, can roll on inflamed endothelium using transient bonds between selectins and their ligands, and integrins and their ligands. When such receptor–ligand bonds last long enough, the leukocyte microvilli become extended and eventually form thin, 20 m long tethers. Tether formation can be observed in blood vessels in vivo and in microfluidic flow chambers. Tethers can also be extracted using micropipette aspiration, biomembrane force probe, optical trap, or atomic force microscopy approaches. Here, we review the biomechanical properties of leukocyte tethers as gleaned from such measurements and discuss the advantages and disadvantages of each approach. We also review and discuss viscoelastic models that describe the dependence of tether formation on time, force, rate of loading, and cell activation. We close by emphasizing the need to combine experimental observations with quantitative models and computer simulations to understand how tether formation is affected by membrane tension, membrane reservoir, and interactions of the membrane with the cytoskeleton.

Download Full-text

Silane-Coating Strategy for Titanium Functionalization Does Not Impair Osteogenesis In Vivo

Materials ◽

10.3390/ma14071814 ◽

2021 ◽

Vol 14 (7) ◽

pp. 1814

Author(s):

Plinio Mendes Senna ◽

Carlos Fernando de Almeida Barros Mourão ◽

Rafael Coutinho Mello-Machado ◽

Kayvon Javid ◽

Pietro Montemezzi ◽

...

Keyword(s):

Bone Formation ◽

Photoelectron Spectroscopy ◽

Titanium Surface ◽

Rabbit Model ◽

Biologically Active ◽

Force Microscopy ◽

Atomic Force ◽

Silane Coating ◽

Titanium Screws

Silane-coating strategy has been used to bind biological compounds to the titanium surface, thereby making implant devices biologically active. However, it has not been determined if the presence of the silane coating itself is biocompatible to osseointegration. The aim of the present study was to evaluate if silane-coating affects bone formation on titanium using a rabbit model. For this, titanium screw implants (3.75 by 6 mm) were hydroxylated in a solution of H2SO4/30% H2O2 for 4 h before silane-coating with 3-aminopropyltriethoxysilane (APTES). A parallel set of titanium screws underwent only the hydroxylation process to present similar acid-etched topography as a control. The presence of the silane on the surface was checked by x-ray photoelectron spectroscopy (XPS), with scanning electron microscopy (SEM) and atomic force microscopy (AFM). A total of 40 titanium screws were implanted in the tibia of ten New Zealand rabbits in order to evaluate bone-to-implant contact (BIC) after 3 weeks and 6 weeks of healing. Silane-coated surface presented higher nitrogen content in the XPS analysis, while micro- and nano-topography of the surface remained unaffected. No difference between the groups was observed after 3 and 6 weeks of healing (p > 0.05, independent t-test), although an increase in BIC occurred over time. These results indicate that silanization of a titanium surface with APTES did not impair the bone formation, indicating that this can be a reliable tool to anchor osteogenic molecules on the surface of implant devices.

Download Full-text

Observation of a Polystyrene Surface Modified by Ultrasonic Scratching Using Atomic Force Microscopy

Japanese Journal of Applied Physics ◽

10.1143/jjap.38.3936 ◽

1999 ◽

Vol 38 (Part 1, No. 6B) ◽

pp. 3936-3939 ◽

Cited By ~ 1

Author(s):

Futoshi Iwata ◽

Tarou Matsumoto ◽

Ryuhei Ogawa ◽

Akira Sasaki

Keyword(s):

Atomic Force Microscopy ◽

Force Microscopy ◽

Polystyrene Surface ◽

Atomic Force ◽

Surface Modified

Download Full-text

Diabetes increases stiffness of live cardiomyocytes measured by atomic force microscopy nanoindentation

AJP Cell Physiology ◽

10.1152/ajpcell.00192.2013 ◽

2014 ◽

Vol 307 (10) ◽

pp. C910-C919 ◽

Cited By ~ 22

Author(s):

Juan C. Benech ◽

Nicolás Benech ◽

Ana I. Zambrana ◽

Inés Rauschert ◽

Verónica Bervejillo ◽

...

Keyword(s):

Atomic Force Microscopy ◽

Physiological Condition ◽

Diabetic Mice ◽

Cell Nuclei ◽

Buffer Solution ◽

Isolated Cardiomyocytes ◽

Force Microscopy ◽

Atomic Force ◽

Myocardial Fibers

Stiffness of live cardiomyocytes isolated from control and diabetic mice was measured using the atomic force microscopy nanoindentation method. Type 1 diabetes was induced in mice by streptozotocin administration. Histological images of myocardium from mice that were diabetic for 3 mo showed disorderly lineup of myocardial cells, irregularly sized cell nuclei, and fragmented and disordered myocardial fibers with interstitial collagen accumulation. Phalloidin-stained cardiomyocytes isolated from diabetic mice showed altered (i.e., more irregular and diffuse) actin filament organization compared with cardiomyocytes from control mice. Sarco/endoplasmic reticulum Ca2+-ATPase (SERCA2a) pump expression was reduced in homogenates obtained from the left ventricle of diabetic animals compared with age-matched controls. The apparent elastic modulus (AEM) for live control or diabetic isolated cardiomyocytes was measured using the atomic force microscopy nanoindentation method in Tyrode buffer solution containing 1.8 mM Ca2+ and 5.4 mM KCl (physiological condition), 100 nM Ca2+ and 5.4 mM KCl (low extracellular Ca2+ condition), or 1.8 mM Ca2+ and 140 mM KCl (contraction condition). In the physiological condition, the mean AEM was 112% higher for live diabetic than control isolated cardiomyocytes (91 ± 14 vs. 43 ± 7 kPa). The AEM was also significantly higher in diabetic than control cardiomyocytes in the low extracellular Ca2+ and contraction conditions. These findings suggest that the material properties of live cardiomyocytes were affected by diabetes, resulting in stiffer cells, which very likely contribute to high diastolic LV stiffness, which has been observed in vivo in some diabetes mellitus patients.

Download Full-text

Surface diagnostics for scale analysis

Water Science & Technology ◽

10.2166/wst.2004.0120 ◽

2004 ◽

Vol 49 (2) ◽

pp. 183-190 ◽

Cited By ~ 8

Author(s):

S. Dunn ◽

S. Impey ◽

C. Kimpton ◽

S.A. Parsons ◽

J. Doyle ◽

...

Keyword(s):

Adhesion Force ◽

Polymer Materials ◽

Rapid Screening ◽

Force Measurements ◽

Energy Materials ◽

Force Microscopy ◽

Atomic Force ◽

Surface Modified ◽

Surface Diagnostics ◽

Microscopy Techniques

Stainless steel, polymethylmethacrylate and polytetrafluoroethylene coupons were analysed for surface topographical and adhesion force characteristics using tapping mode atomic force microscopy and force-distance microscopy techniques. The two polymer materials were surface modified by polishing with silicon carbide papers of known grade. The struvite scaling rate was determined for each coupon and related to the data gained from the surface analysis. The scaling rate correlated well with adhesion force measurements indicating that lower energy materials scale at a lower rate. The techniques outlined in the paper provide a method for the rapid screening of materials in potential scaling applications.

Download Full-text