scholarly journals Conservation of S20 as an Ineffective and Disposable IFNγ-Inducing Determinant of Plasmodium Sporozoites Indicates Diversion of Cellular Immunity

2021 ◽  
Vol 12 ◽  
Author(s):  
Calvin Hon ◽  
Johannes Friesen ◽  
Alyssa Ingmundson ◽  
Diana Scheppan ◽  
Julius C. R. Hafalla ◽  
...  
Keyword(s):  
Genetic Background ◽  
Cell Epitope ◽  
Specific Protein ◽  
Phase Iii ◽  
Mammalian Host ◽  
Pivotal Phase ◽  
Phase Iii Clinical Trials ◽  
Immunogenic Proteins

Despite many decades of research to develop a malaria vaccine, only one vaccine candidate has been explored in pivotal phase III clinical trials. This candidate subunit vaccine consists of a portion of a single Plasmodium antigen, circumsporozoite protein (CSP). This antigen was initially identified in the murine malaria model and shown to contain an immunodominant and protective CD8+ T cell epitope specific to the H-2Kd (BALB/c)-restricted genetic background. A high-content screen for CD8+ epitopes in the H2Kb/Db (C57BL/6)-restricted genetic background, identified two distinct dominant epitopes. In this study, we present a characterization of one corresponding antigen, the Plasmodium sporozoite-specific protein S20. Plasmodium berghei S20 knockout sporozoites and liver stages developed normally in vitro and in vivo. This potent infectivity of s20(-) sporozoites permitted comparative analysis of knockout and wild-type parasites in cell-based vaccination. Protective immunity of irradiation-arrested s20(-) sporozoites in single, double and triple immunizations was similar to irradiated unaltered sporozoites in homologous challenge experiments. These findings demonstrate the presence of an immunogenic Plasmodium pre-erythrocytic determinant, which is not essential for eliciting protection. Although S20 is not needed for colonization of the mammalian host and for initiation of a blood infection, it is conserved amongst Plasmodium species. Malarial parasites express conserved, immunogenic proteins that are not required to establish infection but might play potential roles in diverting cellular immune responses.

scholarly journals Microbiology and Preclinical Review of Omadacycline

2019 ◽  
Vol 69 (Supplement_1) ◽  
pp. S6-S15 ◽  
Author(s):  
James A Karlowsky ◽  
Judith Steenbergen ◽  
George G Zhanel
Keyword(s):  
Legionella Pneumophila ◽  
Animal Studies ◽  
Action Spectrum ◽  
Binding Activity ◽  
Phase Iii ◽  
Phase Iii Clinical Trials ◽  
Clostridioides Difficile ◽  
Semisynthetic Derivative

AbstractOmadacycline is a novel aminomethylcycline antimicrobial and semisynthetic derivative of tetracycline. In vitro, omadacycline displays potent activity against gram-positive and many gram-negative bacteria, including methicillin-resistant Staphylococcus aureus, Streptococcus pneumoniae, β-hemolytic streptococci, vancomycin-resistant Enterococcus, and Enterobacteriaceae. Omadacycline is also active against atypical and anaerobic pathogens, including Legionella pneumophila, Mycoplasma spp., Ureaplasma spp., Bacteroides spp., and Clostridioides difficile. This review outlines the microbiology and preclinical studies of omadacycline, including its mechanism of action; spectrum of activity; protein binding; activity in the presence of surfactant, serum, normal, and pH-adjusted urine, or bacterial biofilms; postantibiotic effect; pharmacodynamic properties; and in vitro and in vivo efficacy. The results of in vitro and in vivo animal studies support the observations made in phase III clinical trials and the clinical development of omadacycline.

Drug-drug interaction (DDI) of darolutamide with cytochrome P450 (CYP) and P-glycoprotein (P-gp) substrates: Results from clinical and in vitro studies.

2019 ◽  
Vol 37 (7_suppl) ◽  
pp. 297-297 ◽  
Author(s):  
Christian Zurth ◽  
Kristina Graudenz ◽  
Karsten Denner ◽  
Timo Korjamo ◽  
Robert Fricke ◽  
...  
Keyword(s):  
Phase I ◽  
Dabigatran Etexilate ◽  
Safety Data ◽  
Liver Microsomes ◽  
Phase Iii ◽  
Castration Resistant Prostate Cancer ◽  
Pivotal Phase ◽  
Cyp3a4 Substrate

297 Background: Maintaining quality of survival, by delaying disease progression and minimizing therapy burden, is critical for patients and has been evaluated in the pivotal phase III ARAMIS study in patients with non-metastatic castration-resistant prostate cancer. Due to comorbidity, elderly men often receive multiple comedications, including CYP and P-gp substrates, eg, simvastatin and digoxin. Enzalutamide and apalutamide, approved androgen receptor (AR) inhibitors, are strong CYP3A4 inducers and thus have potential for CYP-mediated DDIs. The effect of darolutamide, a structurally unique AR antagonist, on CYP activity ( in vitro and in vivo) and P-gp activity ( in vivo) was assessed. Methods: Inhibition of CYP isoforms by Daro was investigated in human liver microsomes using standard substrates. In addition, CYP and P-gp activity during darolutamide treatment was studied in a phase I trial of 15 healthy men who received 75 mg dabigatran etexilate (DABE, P-gp substrate) + 1 mg midazolam (MDZ, CYP3A4 substrate) once followed by 600 mg darolutamide (two 300 mg tablets) twice daily (BID) given with food for 9 days. On day 9, darolutamide was concomitantly administered with a single dose of 75 mg DABE + 1 mg MDZ. Results: Based on in vitro data, no clinically relevant inhibition of CYP1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1, or 3A4 by darolutamide is expected. In 13 evaluable subjects in the phase I study, concomitant darolutamide reduced MDZ Cmax by ~32% and AUC by ~29% vs MDZ alone. Concomitant darolutamide reduced non-conjugated dabigatran Cmax by 16% and AUC by 9% vs DABE alone. The observed treatment-emergent adverse events were consistent with the known safety profile of darolutamide. No new safety risks were revealed by co-administration of darolutamide and DABE or MDZ. Safety data for patients in ARAMIS who received darolutamide, including those with concomitant CYP or P-gp substrates, will be presented. Conclusions: Darolutamide showed only weak effects or none on P-gp, CYP3A4, or any other relevant CYP enzyme. Thus, darolutamide is not expected to cause any clinically relevant DDI with CYP or P-gp substrates, minimizing complications of polypharmacy. Clinical trial information: NCT03237416.

scholarly journals In silico and in vitro analysis of recombinant arginine deiminase from Pseudomonas furukawaii as a potential anticancer enzyme

2021 ◽  
Author(s):  
Rakhi Dhankhar ◽  
Vatika Gupta ◽  
Aparajita Mohanty ◽  
Pooja Gulati
Keyword(s):  
In Silico ◽  
3D Structure ◽  
Cell Epitope ◽  
Mycoplasma Hominis ◽  
Arginine Deiminase ◽  
Phase Iii ◽  
Drug Candidate ◽  
Phase Iii Clinical Trials ◽  
Vitro Analysis

Abstract Arginine deiminase (ADI) is a promising anticancer enzyme that can be employed in amino acid deprivation therapy for the treatment of various arginine auxotrophic tumors. In our previous work, Pseudomonas furukawaii was identified as a potent producer of ADI with optimum activity at physiological pH and temperature. The 3D structure of PfADI was modeled. Immunoinformatics analysis was also carried out to compare the immunogenicity of PfADI with MhADI (Mycoplasma hominis ADI, which is in phase III clinical trials). The PfADI was found to be less immunogenic in terms of number of linear and conformational B cell epitopes and T cell epitope density. The overall antigenicity and allergenicity of PfADI was also lower as compared to MhADI. Thus, the ADI coding arcA gene was cloned and expressed in E. coli BL21. Recombinant ADI of P. furukawaii (PfADI) was purified using affinity chromatography and its molecular mass was estimated to be ~46KDa. PfADI was found to effectively inhibit the HepG2 cells with an IC50 value of 0.1950 IU/ml. PfADI was characterized and the enzyme was found to be stable at human physiological conditions (pH 7 and 37 ⁰C temperature). The Km and Vmax values were found to be 1.90 mM and 1.83 µmol ml-1min-1 respectively. Thus the present in vitro and in silico studies establish PfADI as a potential anticancer drug candidate with improved efficacy and low immunogenicity.

Satraplatin, an oral platinum analog, is active and synergistic with paclitaxel and docetaxel in prostate carcinoma models

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 14620-14620 ◽  
Author(s):  
L. Lamphere ◽  
F. Obermayr ◽  
M. Caligiuri ◽  
G. Unteregger ◽  
M. S. Rudoltz ◽  
...  
Keyword(s):  
Cell Lines ◽  
Nude Mice ◽  
Prostate Carcinoma ◽  
Phase Iii ◽  
Human Prostate ◽  
Growth Delay ◽  
Phase Ii Trials ◽  
Pivotal Phase

14620 Background: Satraplatin is a novel oral platinum analog with potent cytotoxic and antitumor activity in preclinical models. Satraplatin showed activity in hormone refractory prostate cancer (HRPC) and other tumor types in Phase II trials. A pivotal Phase III trial evaluating satraplatin as 2nd-line therapy for HRPC completed accrual of > 900 patients in 2005. Satraplatin’s activity, safety profile and ease of administration make it attractive for combination regimens. Methods: Satraplatin and its active metabolite JM-118 were tested in vitro as single agents in the androgen-sensitive LNCaP and the androgen-insensitive PC-3 and DU-145 human prostate carcinoma (ca.) cell lines. For in vitro combination studies, PC-3 cells were treated with satraplatin or JM-118 either prior to, after, or concomitantly with paclitaxel or docetaxel. The PC-3 cell line was used for in vivo xenograft experiments in nude mice. Paclitaxel was given intravenously on Day 1, satraplatin orally on Days 2 to 6, and paclitaxel again on Day 8. Results: Satraplatin and JM-118 as single agents inhibited the growth of all three prostate ca. cell lines in vitro in a dose dependent fashion. IC50 values for JM-118 were < 1μM. Strong synergism was noted when PC-3 tumor cells were treated in vitro with paclitaxel or docetaxel followed by satraplatin or JM-118. Satraplatin administered orally inhibited the growth of PC-3 xenografts in nude mice. Treatment of advanced PC-3 tumors with paclitaxel (40 mg/kg) and satraplatin (35 mg/kg) was well tolerated and resulted in a Tumor Growth Delay equivalent to 3 Log Cell Kill, an effect superior to that of the single agents. Conclusions: In vitro, satraplatin and its metabolite JM-118 are active as single agents against human prostate ca. cells, and are synergistic with taxanes. In vivo, treatment with paclitaxel followed by satraplatin showed synergism without increased toxicity. These preclinical data support ongoing Phase I and II clinical trials that are evaluating combinations of satraplatin with paclitaxel or docetaxel. [Table: see text]

Ibrexafungerp: A novel oral glucan synthase inhibitor

2019 ◽  
Vol 58 (5) ◽  
pp. 579-592 ◽  
Author(s):  
M R Davis ◽  
M A Donnelley ◽  
G R Thompson
Keyword(s):  
Fungal Pathogens ◽  
Phase Iii ◽  
Tolerability Profile ◽  
Candida Spp ◽  
Glucan Synthase ◽  
Phase Iii Clinical Trials ◽  
In Vivo Animal Models ◽  
Synthase Inhibitor

Abstract Ibrexafungerp is a novel glucan synthase inhibitor currently undergoing phase II and phase III clinical trials. This compound has demonstrated in vitro activity against clinically important fungal pathogens including Candida spp. and Aspergillus spp. It is able to retain activity against many echinocandin-resistant strains of Candida due to differential avidity for the target site compared to echinocandins. In vivo animal models have demonstrated efficacy in murine models of invasive candidiasis, aspergillosis, and pneumocystis. Due to high bioavailability, it can be administered both orally and intravenously. A favorable drug interaction and tolerability profile is observed with this compound. This review summarizes existing data that have either been published or presented at international symposia.

Specific Labeling of Protein Domains with Antibody Fragments

1981 ◽  
Vol 39 ◽  
pp. 416-417
Author(s):  
U. Aebi ◽  
L.E. Buhle ◽  
W.E. Fowler
Keyword(s):  
Image Processing ◽  
Specific Protein ◽  
Antibody Fragments ◽  
Supramolecular Organization ◽  
Two Dimensional ◽  
Ordered Structures ◽  
Virus Capsids ◽  
Processing Techniques

Many important supramolecular structures such as filaments, microtubules, virus capsids and certain membrane proteins and bacterial cell walls exist as ordered polymers or two-dimensional crystalline arrays in vivo. In several instances it has been possible to induce soluble proteins to form ordered polymers or two-dimensional crystalline arrays in vitro. In both cases a combination of electron microscopy of negatively stained specimens with analog or digital image processing techniques has proven extremely useful for elucidating the molecular and supramolecular organization of the constituent proteins. However from the reconstructed stain exclusion patterns it is often difficult to identify distinct stain excluding regions with specific protein subunits. To this end it has been demonstrated that in some cases this ambiguity can be resolved by a combination of stoichiometric labeling of the ordered structures with subunit-specific antibody fragments (e.g. Fab) and image processing of the electron micrographs recorded from labeled and unlabeled structures.

Polyamines and Related Nitrogen Compounds in the Chemotherapy of Neglected Diseases Caused by Kinetoplastids

2018 ◽  
Vol 18 (5) ◽  
pp. 321-368 ◽  
Author(s):  
Juan A. Bisceglia ◽  
Maria C. Mollo ◽  
Nadia Gruber ◽  
Liliana R. Orelli
Keyword(s):  
Drug Targets ◽  
Redox Homeostasis ◽  
Cost Effective ◽  
Structural Features ◽  
Mammalian Host ◽  
Neglected Diseases ◽  
Nitrogen Compounds ◽  
Chemical Structures

Neglected diseases due to the parasitic protozoa Leishmania and Trypanosoma (kinetoplastids) affect millions of people worldwide, and the lack of suitable treatments has promoted an ongoing drug discovery effort to identify novel nontoxic and cost-effective chemotherapies. Polyamines are ubiquitous small organic molecules that play key roles in kinetoplastid parasites metabolism, redox homeostasis and in the normal progression of cell cycles, which differ from those found in the mammalian host. These features make polyamines attractive in terms of antiparasitic drug development. The present work provides a comprehensive insight on the use of polyamine derivatives and related nitrogen compounds in the chemotherapy of kinetoplastid diseases. The amount of literature on this subject is considerable, and a classification considering drug targets and chemical structures were made. Polyamines, aminoalcohols and basic heterocycles designed to target the relevant parasitic enzyme trypanothione reductase are discussed in the first section, followed by compounds directed to less common targets, like parasite SOD and the aminopurine P2 transporter. Finally, the third section comprises nitrogen compounds structurally derived from antimalaric agents. References on the chemical synthesis of the selected compounds are reported together with their in vivo and/or in vitro IC50 values, and structureactivity relationships within each group are analyzed. Some favourable structural features were identified from the SAR analyses comprising protonable sites, hydrophobic groups and optimum distances between them. The importance of certain pharmacophoric groups or amino acid residues in the bioactivity of polyamine derived compounds is also discussed.

scholarly journals Streptococcal Adhesion and Colonization

1997 ◽  
Vol 8 (2) ◽  
pp. 175-200 ◽  
Author(s):  
H.F. Jenkinson ◽  
RJ Lamont
Keyword(s):  
Immune Modulation ◽  
Rational Design ◽  
Repeated Sequence ◽  
Host Cells ◽  
Mammalian Host ◽  
Related Factors ◽  
Bacterial Populations ◽  
Acellular Vaccines

Streptococci express arrays of adhesins on their cell surfaces that facilitate adherence to substrates present in their natural environment within the mammalian host. A consequence of such promiscuous binding ability is that streptococcal cells may adhere simultaneously to a spectrum of substrates, including salivary glycoproteins, extracellular matrix and serum components, host cells, and other microbial cells. The multiplicity of streptococcal adherence interactions accounts, at least in part, for their success in colonizing the oral and epithelial surfaces of humans. Adhesion facilitates colonization and may be a precursor to tissue invasion and immune modulation, events that presage the development of disease. Many of the streptococcal adhesins and virulence-related factors are cell-wall-associated proteins containing repeated sequence blocks of amino acids. Linear sequences, both within the blocks and within non-repetitive regions of the proteins, have been implicated in substrate binding. Sequences and functions of these proteins among the streptococci have become assorted through gene duplication and horizontal transfer between bacterial populations. Several adhesins identified and characterized through in vitro binding assays have been analyzed for in vivo expression and function by means of animal models used for colonization and virulence. Information on the molecular structure of adhesins as related to their in vivo function will allow for the rational design of novel acellular vaccines, recombinant antibodies, and adhesion agonists for the future control or prevention of streptococcal colonization and streptococcal diseases.

scholarly journals Interactions between RNA polymerase and the core recognition element are a determinant of transcription start site selection

2016 ◽  
Vol 113 (21) ◽  
pp. E2899-E2905 ◽  
Author(s):  
Irina O. Vvedenskaya ◽  
Hanif Vahedian-Movahed ◽  
Yuanchao Zhang ◽  
Deanne M. Taylor ◽  
Richard H. Ebright ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Transcription Start Site ◽  
Transcription Initiation ◽  
Specific Protein ◽  
Start Site ◽  
Transcription Start ◽  
Transcription Bubble ◽  
Recognition Element

During transcription initiation, RNA polymerase (RNAP) holoenzyme unwinds ∼13 bp of promoter DNA, forming an RNAP-promoter open complex (RPo) containing a single-stranded transcription bubble, and selects a template-strand nucleotide to serve as the transcription start site (TSS). In RPo, RNAP core enzyme makes sequence-specific protein–DNA interactions with the downstream part of the nontemplate strand of the transcription bubble (“core recognition element,” CRE). Here, we investigated whether sequence-specific RNAP–CRE interactions affect TSS selection. To do this, we used two next-generation sequencing-based approaches to compare the TSS profile of WT RNAP to that of an RNAP derivative defective in sequence-specific RNAP–CRE interactions. First, using massively systematic transcript end readout, MASTER, we assessed effects of RNAP–CRE interactions on TSS selection in vitro and in vivo for a library of 47 (∼16,000) consensus promoters containing different TSS region sequences, and we observed that the TSS profile of the RNAP derivative defective in RNAP–CRE interactions differed from that of WT RNAP, in a manner that correlated with the presence of consensus CRE sequences in the TSS region. Second, using 5′ merodiploid native-elongating-transcript sequencing, 5′ mNET-seq, we assessed effects of RNAP–CRE interactions at natural promoters in Escherichia coli, and we identified 39 promoters at which RNAP–CRE interactions determine TSS selection. Our findings establish RNAP–CRE interactions are a functional determinant of TSS selection. We propose that RNAP–CRE interactions modulate the position of the downstream end of the transcription bubble in RPo, and thereby modulate TSS selection, which involves transcription bubble expansion or transcription bubble contraction (scrunching or antiscrunching).

scholarly journals Microtubule Actin Cross-Linking Factor (Macf)

1999 ◽  
Vol 147 (6) ◽  
pp. 1275-1286 ◽  
Author(s):  
Conrad L. Leung ◽  
Dongming Sun ◽  
Min Zheng ◽  
David R. Knowles ◽  
Ronald K.H. Liem
Keyword(s):  
Calcium Binding ◽  
Coiled Coil ◽  
Specific Protein ◽  
Binding Domain ◽  
Full Length ◽  
Actin Binding ◽  
Cross Linking ◽  
Actin Binding Domain

We cloned and characterized a full-length cDNA of mouse actin cross-linking family 7 (mACF7) by sequential rapid amplification of cDNA ends–PCR. The completed mACF7 cDNA is 17 kb and codes for a 608-kD protein. The closest relative of mACF7 is the Drosophila protein Kakapo, which shares similar architecture with mACF7. mACF7 contains a putative actin-binding domain and a plakin-like domain that are highly homologous to dystonin (BPAG1-n) at its NH2 terminus. However, unlike dystonin, mACF7 does not contain a coiled–coil rod domain; instead, the rod domain of mACF7 is made up of 23 dystrophin-like spectrin repeats. At its COOH terminus, mACF7 contains two putative EF-hand calcium-binding motifs and a segment homologous to the growth arrest–specific protein, Gas2. In this paper, we demonstrate that the NH2-terminal actin-binding domain of mACF7 is functional both in vivo and in vitro. More importantly, we found that the COOH-terminal domain of mACF7 interacts with and stabilizes microtubules. In transfected cells full-length mACF7 can associate not only with actin but also with microtubules. Hence, we suggest a modified name: MACF (microtubule actin cross-linking factor). The properties of MACF are consistent with the observation that mutations in kakapo cause disorganization of microtubules in epidermal muscle attachment cells and some sensory neurons.

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