scholarly journals Lysine-selective molecular tweezers are cell penetrant and concentrate in lysosomes

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Zizheng Li ◽  
Ibrar Siddique ◽  
Inesa Hadrović ◽  
Abbna Kirupakaran ◽  
Jiwen Li ◽  
...  
Keyword(s):  
Animal Models ◽  
Mechanism Of Action ◽  
Bacterial Biofilm ◽  
Low Doses ◽  
Molecular Tweezers ◽  
Main Site ◽  
Main Compound ◽  
Drug Candidates ◽  
Acidic Compartments

AbstractLysine-selective molecular tweezers are promising drug candidates against proteinopathies, viral infection, and bacterial biofilm. Despite demonstration of their efficacy in multiple cellular and animal models, important questions regarding their mechanism of action, including cell penetrance and intracellular distribution, have not been answered to date. The main impediment to answering these questions has been the low intrinsic fluorescence of the main compound tested to date, called CLR01. Here, we address these questions using new fluorescently labeled molecular tweezers derivatives. We show that these compounds are internalized in neurons and astrocytes, at least partially through dynamin-dependent endocytosis. In addition, we demonstrate that the molecular tweezers concentrate rapidly in acidic compartments, primarily lysosomes. Accumulation of molecular tweezers in lysosomes may occur both through the endosomal-lysosomal pathway and via the autophagy-lysosome pathway. Moreover, by visualizing colocalization of molecular tweezers, lysosomes, and tau aggregates we show that lysosomes likely are the main site for the intracellular anti-amyloid activity of molecular tweezers. These findings have important implications for the mechanism of action of molecular tweezers in vivo, explaining how administration of low doses of the compounds achieves high effective concentrations where they are needed, and supporting the development of these compounds as drugs for currently cureless proteinopathies.

scholarly journals Lysine-selective molecular tweezers are cell-penetrant and concentrate in lysosomes

2021 ◽  
Author(s):  
Zizheng Li ◽  
Ibrar Siddique ◽  
Inesa Hadrović ◽  
Jiwen Li ◽  
Ye Zhang ◽  
...  
Keyword(s):  
Animal Models ◽  
Viral Infection ◽  
Mechanism Of Action ◽  
Low Doses ◽  
Molecular Tweezers ◽  
Main Site ◽  
Main Compound ◽  
Drug Candidates ◽  
Acidic Compartments

Abstract Lysine-selective molecular tweezers are promising drug candidates against proteinopathies and viral infection. Despite demonstration of their efficacy in multiple cellular and animal models, important questions regarding their mechanism of action, including cell penetrance and intracellular distribution, have not been answered to date. The main impediment to answering these questions has been the low intrinsic fluorescence of the main compound tested to date, called CLR01. Here, we address these questions using new fluorescently labeled molecular tweezers derivatives. We show that these compounds are internalized in neurons and astrocytes, at least partially through dynamin-dependent endocytosis. In addition, we demonstrate that the molecular tweezers concentrate rapidly in acidic compartments, primarily lysosomes. Accumulation of molecular tweezers in lysosomes may occur both through the endosomal-lysosomal pathway and via the autophagy-lysosome pathway. Moreover, by visualizing colocalization of molecular tweezers, lysosomes, and tau aggregates we show that lysosomes likely are the main site for the intracellular anti-amyloid activity of molecular tweezers. These findings have important implications for the mechanism of action of molecular tweezers in vivo, explaining how administration of low doses of the compounds achieves high effective concentrations where they are needed, and supporting the development of these compounds as drugs for currently cureless proteinopathies.

scholarly journals Impetigo Animal Models: A Review of Their Feasibility and Clinical Utility for Therapeutic Appraisal of Investigational Drug Candidates

Antibiotics ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 694
Author(s):  
Solomon Abrha ◽  
Andrew Bartholomaeus ◽  
Wubshet Tesfaye ◽  
Jackson Thomas
Keyword(s):  
Animal Models ◽  
In Vivo Studies ◽  
Therapeutic Drug ◽  
Investigational Drug ◽  
Skin Infections ◽  
Drug Candidates ◽  
First Line Therapy ◽  
Superficial Skin

Impetigo (school sores), a superficial skin infection commonly seen in children, is caused by the gram-positive bacteria Staphylococcus aureus and/or Streptococcus pyogenes. Antibiotic treatments, often topical, are used as the first-line therapy for impetigo. The efficacy of potential new antimicrobial compounds is first tested in in vitro studies and, if effective, followed by in vivo studies using animal models and/or humans. Animal models are critical means for investigating potential therapeutics and characterizing their safety profile prior to human trials. Although several reviews of animal models for skin infections have been published, there is a lack of a comprehensive review of animal models simulating impetigo for the selection of therapeutic drug candidates. This review critically examines the existing animal models for impetigo and their feasibility for testing the in vivo efficacy of topical treatments for impetigo and other superficial bacterial skin infections.

scholarly journals Critical Considerations for the Design of Multi-Organ Microphysiological Systems (MPS)

2021 ◽  
Vol 9 ◽  
Author(s):  
Mridu Malik ◽  
Yang Yang ◽  
Parinaz Fathi ◽  
Gretchen J. Mahler ◽  
Mandy B. Esch
Keyword(s):  
Animal Models ◽  
Drug Toxicity ◽  
New Drugs ◽  
Drug Candidate ◽  
Preclinical Studies ◽  
Toxicity Screening ◽  
Drug Candidates ◽  
Microphysiological Systems

Identification and approval of new drugs for use in patients requires extensive preclinical studies and clinical trials. Preclinical studies rely on in vitro experiments and animal models of human diseases. The transferability of drug toxicity and efficacy estimates to humans from animal models is being called into question. Subsequent clinical studies often reveal lower than expected efficacy and higher drug toxicity in humans than that seen in animal models. Microphysiological systems (MPS), sometimes called organ or human-on-chip models, present a potential alternative to animal-based models used for drug toxicity screening. This review discusses multi-organ MPS that can be used to model diseases and test the efficacy and safety of drug candidates. The translation of an in vivo environment to an in vitro system requires physiologically relevant organ scaling, vascular dimensions, and appropriate flow rates. Even small changes in those parameters can alter the outcome of experiments conducted with MPS. With many MPS devices being developed, we have outlined some established standards for designing MPS devices and described techniques to validate the devices. A physiologically realistic mimic of the human body can help determine the dose response and toxicity effects of a new drug candidate with higher predictive power.

scholarly journals Are Animal Studies of Antipsychotics Appropriately Dosed?: Lessons from the Bedside to the Bench

2000 ◽  
Vol 45 (3) ◽  
pp. 241-246 ◽  
Author(s):  
Shitij Kapur ◽  
Marie-Louise Wadenberg ◽  
Gary Remington
Keyword(s):  
Positron Emission Tomography ◽  
Side Effects ◽  
Animal Models ◽  
Mechanism Of Action ◽  
Half Life ◽  
Animal Studies ◽  
Emission Tomography ◽  
Low Doses ◽  
Extrapyramidal Side Effects ◽  
Positron Emission

Animal models are crucial for understanding the mechanism of action of antipsychotics. However, the dose of an antipsychotic in animal studies is often arbitrarily chosen, with haloperidol 1 mg/kg being a rather common standard. Recent clinical positron emission tomography (PET) studies in patients show all antipsychotics to block dopamine D2 receptors, and most are effective at doses that lead to 60% to 80% D2 occupancy. When occupancy exceeds 80%, the incidence of side effects rises sharply. To use this “bedside” information to inform the “bench,” we measured D2 occupancy in rats using a method similar in principle to the [11 C]-raclopride PET method in humans. We found that: 1) as in humans, haloperidol is effective in animal models of antipsychotic action when D2 occupancy > 70% and leads to effects in models of extrapyramidal side effects when D2 occupancy is > 80%; 2) very low doses, 0.06 mg/kg/sc, cause acute D2 occupancy of 75%; 3) and even doses that acutely saturate D2 receptors give little D2 occupancy after 24 hours due to the very short half-life of haloperidol in rats (2.5 hours versus 24 hours in humans). We conclude that most previous animal studies of antipsychotics have used doses giving rise to inappropriately high acute D2 occupancy and inappropriately low D2 occupancy between doses. We exemplify how this dosing confounder could lead to inappropriate conclusions. Data from the bedside translated to the bench—using D2 occupancy as a mediating variable—will lead to more valid animal models.

Involvement of 5-Hydroxytryptamine in Platelet Aggregation In Vivo in Rats and Guinea Pigs

1989 ◽  
Vol 61 (03) ◽  
pp. 463-467 ◽  
Author(s):  
G M Smith
Keyword(s):  
Platelet Count ◽  
Guinea Pigs ◽  
Platelet Adhesion ◽  
Adenosine Diphosphate ◽  
Rate Of Return ◽  
Low Doses ◽  
Dose Dependent ◽  
Higher Doses ◽  
Rat Platelets

SummaryIn this study, 5-hydroxytryptamine (5-HT) caused a dose- dependent fall in the circulating platelet count suggesting that 5-HT receptors are activated in rat platelets to cause platelet adhesion and aggregation. When low doses of adenosine diphosphate (ADP) were simultaneously injected with 5-HT, there was a significant potentiation of the responses to ADR Ketanserin significantly reduced the potentiated responses. When higher doses of ADP were infused with bolus injections of 5-HT there was no potentiation and ketanserin did not reduce these responses. Ketanserin did not inhibit the collagen-induced fall in circulating platelet count, but did significantly increase the rate of return to the basal platelet count compared with control. 5-HT did not cause a fall in platelet count in guinea-pigs

Glial cytotoxicity of low doses of cadmium as a model of heavy metal pollution influence on vertebrates

2020 ◽  
Vol 31 (1) ◽  
pp. 3-10
Author(s):  
V. S. Nedzvetsky ◽  
V. Ya. Gasso ◽  
A. M. Hahut ◽  
I. A. Hasso
Keyword(s):  
Oxidative Stress ◽  
Cell Death ◽  
Programmed Cell Death ◽  
Oxidative Damage ◽  
Cadmium Chloride ◽  
Glioma Cells ◽  
Low Doses ◽  
Genotoxic Effects ◽  
Cadmium Ions

Cadmium is a common transition metal that entails an extremely wide range of toxic effects in humans and animals. The cytotoxicity of cadmium ions and its compounds is due to various genotoxic effects, including both DNA damage and chromosomal aberrations. Some bone diseases, kidney and digestive system diseases are determined as pathologies that are closely associated with cadmium intoxication. In addition, cadmium is included in the list of carcinogens because of its ability to initiate the development of tumors of several forms of cancer under conditions of chronic or acute intoxication. Despite many studies of the effects of cadmium in animal models and cohorts of patients, in which cadmium effects has occurred, its molecular mechanisms of action are not fully understood. The genotoxic effects of cadmium and the induction of programmed cell death have attracted the attention of researchers in the last decade. In recent years, the results obtained for in vivo and in vitro experimental models have shown extremely high cytotoxicity of sublethal concentrations of cadmium and its compounds in various tissues. One of the most studied causes of cadmium cytotoxicity is the development of oxidative stress and associated oxidative damage to macromolecules of lipids, proteins and nucleic acids. Brain cells are most sensitive to oxidative damage and can be a critical target of cadmium cytotoxicity. Thus, oxidative damage caused by cadmium can initiate genotoxicity, programmed cell death and inhibit their viability in the human and animal brains. To test our hypothesis, cadmium cytotoxicity was assessed in vivo in U251 glioma cells through viability determinants and markers of oxidative stress and apoptosis. The result of the cell viability analysis showed the dose-dependent action of cadmium chloride in glioma cells, as well as the generation of oxidative stress (p <0.05). Calculated for 48 hours of exposure, the LD50 was 3.1 μg×ml-1. The rates of apoptotic death of glioma cells also progressively increased depending on the dose of cadmium ions. A high correlation between cadmium concentration and apoptotic response (p <0.01) was found for cells exposed to 3–4 μg×ml-1 cadmium chloride. Moreover, a significant correlation was found between oxidative stress (lipid peroxidation) and induction of apoptosis. The results indicate a strong relationship between the generation of oxidative damage by macromolecules and the initiation of programmed cell death in glial cells under conditions of low doses of cadmium chloride. The presented results show that cadmium ions can induce oxidative damage in brain cells and inhibit their viability through the induction of programmed death. Such effects of cadmium intoxication can be considered as a model of the impact of heavy metal pollution on vertebrates.

Highly Potent rhenium(I) Tricarbonyl Complexes with Dual Anticancer and Anti-Angiogenic Activity Against Colorectal Carcinoma

2020 ◽  
Author(s):  
Joachim Delasoie ◽  
Aleksandar Pavic ◽  
Noémie Voutier ◽  
Sandra Vojnovic ◽  
Aurélien Crochet ◽  
...  
Keyword(s):  
Colorectal Carcinoma ◽  
Anticancer Drugs ◽  
Xenograft Model ◽  
Therapeutic Window ◽  
Low Doses ◽  
Sunitinib Malate ◽  
Angiogenic Activity ◽  
Antimetastatic Activity ◽  
Clinical Drugs

Synthesized and characterized a series of rhenium(I) trycarbonyl-based complexes with increased lipophilicity. Two of these novel compounds were discovered to possess remarkable anticancer, anti-angiogenic and antimetastatic activity <i>in vivo</i> (zebrafish-human CRC xenograft model), being effective at very low doses (1-3 µM). At doses as high as 250 µM the complexes did not provoke toxicity issues encountered in clinical anticancer drugs (cardio-, hepato-, and myelotoxicity). The two compounds exceed the antiproliferative and anti-angiogenic potency of clinical drugs cisplatin and sunitinib-malate, and display a large therapeutic window.

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