Toxoplasma gondii is a widespread apicomplexan parasite that can cause severe disease in its human hosts. The ability of T. gondii and other apicomplexan parasites to invade into, egress from, and ...move between cells of the hosts they infect is critical to parasite virulence and disease progression. An unusual and highly conserved parasite myosin motor (TgMyoA) plays a central role in T. gondii motility. The goal of this work was to determine whether the parasite's motility and lytic cycle can be disrupted through pharmacological inhibition of TgMyoA, as an approach to altering disease progression in vivo. To this end, we first sought to identify inhibitors of TgMyoA by screening a collection of 50,000 structurally diverse small molecules for inhibitors of the recombinant motor's actin-activated ATPase activity. The top hit to emerge from the screen, KNX-002, inhibited TgMyoA with little to no effect on any of the vertebrate myosins tested. KNX-002 was also active against parasites, inhibiting parasite motility and growth in culture in a dose-dependent manner. We used chemical mutagenesis, selection in KNX-002, and targeted sequencing to identify a mutation in TgMyoA (T130A) that renders the recombinant motor less sensitive to compound. Compared to wild-type parasites, parasites expressing the T130A mutation showed reduced sensitivity to KNX-002 in motility and growth assays, confirming TgMyoA as a biologically relevant target of KNX-002. Finally, we present evidence that KNX-002 can slow disease progression in mice infected with wild-type parasites, but not parasites expressing the resistance-conferring TgMyoA T130A mutation. Taken together, these data demonstrate the specificity of KNX-002 for TgMyoA, both in vitro and in vivo, and validate TgMyoA as a druggable target in infections with T. gondii. Since TgMyoA is essential for virulence, conserved in apicomplexan parasites, and distinctly different from the myosins found in humans, pharmacological inhibition of MyoA offers a promising new approach to treating the devastating diseases caused by T. gondii and other apicomplexan parasites.
This work uncovers interactions between various signaling pathways that govern
egress. Specifically, we compare the function of three canonical calcium-dependent protein kinases (CDPKs) using ...chemical-genetic and conditional-depletion approaches. We describe the function of a previously uncharacterized CDPK, CDPK2A, in the
lytic cycle, demonstrating that it contributes to parasite fitness through regulation of microneme discharge, gliding motility, and egress from infected host cells. Comparison of analog-sensitive kinase alleles and conditionally depleted alleles uncovered epistasis between CDPK2A and CDPK1, implying a partial functional redundancy. Understanding the topology of signaling pathways underlying key events in the parasite life cycle can aid in efforts targeting kinases for anti-parasitic therapies.
Recent advances in malaria genetics and genomics have transformed many aspects of malaria research in areas of molecular evolution, epidemiology, transmission, host–parasite interaction, drug ...resistance, pathogenicity, and vaccine development. Here, in addition to introducing some background information on malaria parasite biology, parasite genetics/genomics, and genotyping methods, we discuss some applications of genetic and genomic approaches in vaccine development and in studying interactions with microbiota. Genetic and genomic data can be used to search for novel vaccine targets, design an effective vaccine strategy, identify protective antigens in a whole-organism vaccine, and evaluate the efficacy of a vaccine. Microbiota has been shown to influence disease outcomes and vaccine efficacy; studying the effects of microbiota in pathogenicity and immunity may provide information for disease control. Malaria genetics and genomics will continue to contribute greatly to many fields of malaria research.
Self-assembled monolayers (SAMs) formed from thiophenol, 1,1‘-biphenyl-4-thiol, 1,1‘;4‘,1‘ ‘-terphenyl-4-thiol, and anthracene-2-thiol on polycrystalline Au and Ag were characterized by X-ray ...photoelectron spectroscopy and angle-resolved near-edge X-ray absorption fine structure spectroscopy. With the exception of the poorly defined thiophenol film on Au, all thioaromatic molecules were found to form highly oriented and densely packed SAMs on both substrates. The molecular orientation and orientational order of the adsorbed thioaromatic molecules depends on the number of aromatic rings, the substrate, and the rigidity of the aromatic system. The molecules, which on average are slightly inclined with respect to the surface normal, show a less tilted orientation with increasing length of the aromatic chain, and as observed for aliphatic SAMs, they exhibit smaller tilt angles on Ag than on Au. However, the difference in the tilt angles for aromatic SAMs on Au and Ag is smaller than that observed in the aliphatic films. A comparison of the monolayers formed from p-terphenylthiol and anthracenethiol films suggests that a higher molecular rigidity has only a slight effect on the final molecular orientation within the respective SAMs.
Pathological tortuosity of the internal carotid artery ranks next to atherosclerosis amongst causes leading to development of ischaemic strokes. In some patients pathological tortuosity of the ...internal carotid artery is combined with pathological kinking of the common carotid artery. Existing methods of surgical treatment for such concomitant pathology include stegewise elimination of kinking of the internal then common carotid artery, with two anastomoses sequentially formed, thus increasing the overall duration of arterial cross-clamping an prolonging cerebral ischaemia. Another method consists of resection of the common carotid artery with bringing down its bifurcation, restoration of straightness of the internal carotid artery, and formation of an end-to-end anastomosis. The second technique is often associated with technical requirement for ligation of the external carotid artery. In the presence of prolonged atherosclerotic lesions of the bifurcation of the internal and external carotid arteries, this method does not always allow carrying out adequate endarterectomy and fix the intima of the internal carotid artery distal to the bifurcation. The authors developed a method of surgical treatment of patients with a combination of pathological kinking of carotid arteries, providing herein a detailed description of the procedure of performing an operation according to an original technique. The proposed method of reconstruction makes it possible to eliminate pathological kinking of the common and internal carotid arteries in single cross-clamping of vessels, to preserve patency of the external carotid artery and in the presence of an atherosclerotic lesion of the bifurcation to perform adequate endarterectomy. Over the period from 2015 to 2019, a total of 10 patients were operated on according to this technique at the Municipal Vascular Centre of Samara, with no postoperative complications observed. The proposed technique of a reconstructive operation may be effectively used in patients with cerebral ischaemia in concomitant pathological kinking of the common and internal carotid arteries.
Summary Objectives We aimed to determine the prognostic significance of receptor activator of nuclear factor kappa-B ligand (RANKL), RANK and osteoprotegerin (OPG) in patients with oral squamous cell ...carcinoma (OSCC). Materials and methods The protein expression of RANKL, RANK and OPG was assessed by immunohistochemistry on pretreatment biopsies of 93 patients with locally advanced OSCC who received preoperative chemoradiotherapy (CRT). The primary endpoint was cancer-specific survival. Secondary endpoints were correlation of biomarkers with bone invasion and pathological tumor response. Kaplan–Meier curves and Cox regression models were used for survival analyses. Results A significantly higher OPG expression was demonstrated in patients with malignant bone invasion and non-responders to CRT as compared to patients without bone invasion and responders ( p = 0.032 and p = 0.033, respectively). Multivariate analysis revealed that higher OPG expression was independently associated with shorter cancer-specific survival ( p = 0.04). The expression status of RANKL and RANK was not significantly related to clinicopathological characteristics and had no impact on survival of OSCC patients. Conclusion Upregulation of OPG expression is associated with bone invasion, poor pathological tumor regression to neoadjuvant CRT, and worse long-term cancer-specific survival in patients with locally advanced OSCC. Our results indicate that OPG may be a novel prognostic biomarker in oral cancer.
Chemically defined surface patterning has been achieved via irradiation with low‐energy electrons. Irradiation of nitro‐arene‐thiol monolayers leads to the reduction of the nitro groups to amino ...groups, which can then be further chemically modified. The Figure shows such a monolayer that was irradiated through a copper grid followed by acylation with trifluoroacetic acid anhydride.
Apicomplexa is a large phylum of intracellular parasites that are notable for the diseases they cause, including toxoplasmosis, malaria, and cryptosporidiosis. A conserved motile system is critical ...to their life cycles and drives directional gliding motility between cells, as well as invasion of and egress from host cells. However, our understanding of this system is limited by a lack of measurements of the forces driving parasite motion. We used a laser trap to measure the function of the motility apparatus of living
by adhering a microsphere to the surface of an immobilized parasite. Motion of the microsphere reflected underlying forces exerted by the motile apparatus. We found that force generated at the parasite surface begins with no preferential directionality but becomes directed toward the rear of the cell after a period of time. The transition from nondirectional to directional force generation occurs on spatial intervals consistent with the lateral periodicity of structures associated with the membrane pellicle and is influenced by the kinetics of actin filament polymerization and cytoplasmic calcium. A lysine methyltransferase regulates both the magnitude and polarization of the force. Our work provides a novel means to dissect the motile mechanisms of these pathogens.
Objectives to improve the results of surgical treatment of patients with T1-T2 stages of cancer in the supraglottic and ventricular region by using endolaryngeal resections. Material and methods.The ...study was held in Samara Regional Clinical Oncology Center from 2011 to 2016. We analysed 97 case histories of patients diagnosed with stage 0-I laryngeal cancer. The patients were divided into 2 groups depending on the selected organ-preserving method of surgical treatment. The patients of the control group were subjected to open resection of the larynx (laryngofissure). While the patients of the main group received the endolaryngeal resection using an endoscopic rack, a suspension system, a laryngoscope, hard endoscopes of 0, 30, 45 degrees, as well as electrosurgical cutting and endolaryngeal instruments. Results.The duration of the operation, blood loss, and bed day number was significantly less in patients of the main group in comparison with the control group. Also, the percentage of common complications in the main group was lower in relation to the control group. The three-year relapse-free and overall survival was not significantly different between the study groups. Conclusion.According to our observations, the endolaryngeal resections in treatment of the initial stages of laryngeal cancer do not impair the results of treatment and do not significantly affect the survival of this category of patients.
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