scholarly journals The hummingbird's tongue: a self-assembling capillary syphon

2012 ◽  
Vol 279 (1749) ◽  
pp. 4990-4996 ◽  
Author(s):  
Wonjung Kim ◽  
François Peaudecerf ◽  
Maude W. Baldwin ◽  
John W. M. Bush
Keyword(s):  
Theoretical Model ◽  
Theoretical Investigation ◽  
Intake Rate ◽  
Relative Importance ◽  
Capillary Suction ◽  
Trapping Mechanism ◽  
Self Assembling ◽  
Natural Settings ◽  
Energy Intake Rate

We present the results of a combined experimental and theoretical investigation of the dynamics of drinking in ruby-throated hummingbirds. In vivo observations reveal elastocapillary deformation of the hummingbird's tongue and capillary suction along its length. By developing a theoretical model for the hummingbird's drinking process, we investigate how the elastocapillarity affects the energy intake rate of the bird and how its open tongue geometry reduces resistance to nectar uptake. We note that the tongue flexibility is beneficial for accessing, transporting and unloading the nectar. We demonstrate that the hummingbird can attain the fastest nectar uptake when its tongue is roughly semicircular. Finally, we assess the relative importance of capillary suction and a recently proposed fluid trapping mechanism, and conclude that the former is important in many natural settings.

scholarly journals Formulation and in vitro evaluation of self-nanoemulsifying liquisolid tablets of furosemide

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Lena Dalal ◽  
Abdul Wahab Allaf ◽  
Hind El-Zein
Keyword(s):  
Theoretical Model ◽  
Castor Oil ◽  
In Vivo Studies ◽  
Coating Materials ◽  
Peg 400 ◽  
The Mean ◽  
Usp Apparatus ◽  
Solid System

AbstractSelf-nanoemulsifying drug delivery systems (SNEDDS) were used to enhance the dissolution rate of furosemide as a model for class IV drugs and the system was solidified into liquisolid tablets. SNEDDS of furosemide contained 10% Castor oil, 60% Cremophor EL, and 30% PEG 400. The mean droplets size was 17.9 ± 4.5 nm. The theoretical model was used to calculate the amounts of the carrier (Avicel PH101) and coating materials (Aerosil 200) to prepare liquisolid powder. Carrier/coating materials ratio of 5/1 was used and Ludipress was added to the solid system, thus tablets with hardness of 45 ± 2 N were obtained. Liquisolid tablets showed 2-folds increase in drug release as compared to the generic tablets after 60 min in HCl 0.1 N using USP apparatus-II. Furosemide loaded SNEDDS tablets have great prospects for further in vivo studies, and the theoretical model is useful for calculating the adequate amounts of adsorbents required to solidify these systems.

scholarly journals Newly Developed Self-Assembling Antioxidants as Potential Therapeutics for the Cancers

2021 ◽  
Vol 11 (2) ◽  
pp. 92 ◽  
Author(s):  
Babita Shashni ◽  
Yukio Nagasaki
Keyword(s):  
Cancer Survival ◽  
Self Assembling ◽  
Therapeutic Regime ◽  
Cancer Models ◽  
Secondary Messengers ◽  
Potential Therapeutics ◽  
Target Effects ◽  
Tempo Radical

Elevated reactive oxygen species (ROS) have been implicated as significant for cancer survival by functioning as oncogene activators and secondary messengers. Hence, the attenuation of ROS-signaling pathways in cancer by antioxidants seems a suitable therapeutic regime for targeting cancers. Low molecular weight (LMW) antioxidants such as 2,2,6,6-tetramethylpyperidine-1-oxyl (TEMPO), although they are catalytically effective in vitro, exerts off-target effects in vivo due to their size, thus, limiting their clinical use. Here, we discuss the superior impacts of our TEMPO radical-conjugated self-assembling antioxidant nanoparticle (RNP) compared to the LMW counterpart in terms of pharmacokinetics, therapeutic effect, and adverse effects in various cancer models.

scholarly journals A biomimetic platelet based on assembling peptides initiates artificial coagulation

2020 ◽  
Vol 6 (22) ◽  
pp. eaaz4107
Author(s):  
Pei-Pei Yang ◽  
Kuo Zhang ◽  
Ping-Ping He ◽  
Yu Fan ◽  
Xuejiao J. Gao ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Binding Sites ◽  
Therapeutic Strategy ◽  
Critical Role ◽  
The Self ◽  
Membrane Glycoprotein ◽  
Tumor Site ◽  
Self Assembling ◽  
Receptor Interactions

Platelets play a critical role in the regulation of coagulation, one of the essential processes in life, attracting great attention. However, mimicking platelets for in vivo artificial coagulation is still a great challenge due to the complexity of the process. Here, we design platelet-like nanoparticles (pNPs) based on self-assembled peptides that initiate coagulation and form clots in blood vessels. The pNPs first bind specifically to a membrane glycoprotein (i.e., CD105) overexpressed on angiogenetic endothelial cells in the tumor site and simultaneously transform into activated platelet-like nanofibers (apNFs) through ligand-receptor interactions. Next, the apNFs expose more binding sites and recruit and activate additional pNPs, forming artificial clots in both phantom and animal models. The pNPs are proven to be safe in mice without systemic coagulation. The self-assembling peptides mimic platelets and achieve artificial coagulation in vivo, thus providing a promising therapeutic strategy for tumors.

scholarly journals Inducible ablation of mouse Langerhans cells diminishes but fails to abrogate contact hypersensitivity

2005 ◽  
Vol 169 (4) ◽  
pp. 569-576 ◽  
Author(s):  
Clare L. Bennett ◽  
Erwin van Rijn ◽  
Steffen Jung ◽  
Kayo Inaba ◽  
Ralph M. Steinman ◽  
...  
Keyword(s):  
Dendritic Cells ◽  
Steady State ◽  
Diphtheria Toxin ◽  
Langerhans Cells ◽  
Contact Hypersensitivity ◽  
Relative Importance ◽  
Skin Immunity

Langerhans cells (LC) form a unique subset of dendritic cells (DC) in the epidermis but so far their in vivo functions in skin immunity and tolerance could not be determined, in particular in relation to dermal DC (dDC). Here, we exploit a novel diphtheria toxin (DT) receptor (DTR)/DT-based system to achieve inducible ablation of LC without affecting the skin environment. Within 24 h after intra-peritoneal injection of DT into Langerin-DTR mice LC are completely depleted from the epidermis and only begin to return 4 wk later. LC deletion occurs by apoptosis in the absence of inflammation and, in particular, the dDC compartment is not affected. In LC-depleted mice contact hypersensitivity (CHS) responses are significantly decreased, although ear swelling still occurs indicating that dDC can mediate CHS when necessary. Our results establish Langerin-DTR mice as a unique tool to study LC function in the steady state and to explore their relative importance compared with dDC in orchestrating skin immunity and tolerance.

scholarly journals De novo design of self-assembling helical protein filaments

Science ◽  
2018 ◽  
Vol 362 (6415) ◽  
pp. 705-709 ◽  
Author(s):  
Hao Shen ◽  
Jorge A. Fallas ◽  
Eric Lynch ◽  
William Sheffler ◽  
Bradley Parry ◽  
...  
Keyword(s):  
De Novo ◽  
Computational Design ◽  
Building Blocks ◽  
Repeat Units ◽  
Self Assembling ◽  
Wide Range ◽  
Helical Protein ◽  
Monomeric Proteins

We describe a general computational approach to designing self-assembling helical filaments from monomeric proteins and use this approach to design proteins that assemble into micrometer-scale filaments with a wide range of geometries in vivo and in vitro. Cryo–electron microscopy structures of six designs are close to the computational design models. The filament building blocks are idealized repeat proteins, and thus the diameter of the filaments can be systematically tuned by varying the number of repeat units. The assembly and disassembly of the filaments can be controlled by engineered anchor and capping units built from monomers lacking one of the interaction surfaces. The ability to generate dynamic, highly ordered structures that span micrometers from protein monomers opens up possibilities for the fabrication of new multiscale metamaterials.

scholarly journals Overview of DNA Self-Assembling: Progresses in Biomedical Applications

Pharmaceutics ◽  
2018 ◽  
Vol 10 (4) ◽  
pp. 268 ◽  
Author(s):  
Andreia Jorge ◽  
Ramon Eritja
Keyword(s):  
Programming Languages ◽  
Biomedical Applications ◽  
Great Promise ◽  
Dna Nanostructures ◽  
Modular Assembly ◽  
Molecular Programming ◽  
Self Assembling ◽  
Theranostic Agents ◽  
Assembly Principles

Molecular self-assembling is ubiquitous in nature providing structural and functional machinery for the cells. In recent decades, material science has been inspired by the nature’s assembly principles to create artificially higher-order structures customized with therapeutic and targeting molecules, organic and inorganic fluorescent probes that have opened new perspectives for biomedical applications. Among these novel man-made materials, DNA nanostructures hold great promise for the modular assembly of biocompatible molecules at the nanoscale of multiple shapes and sizes, designed via molecular programming languages. Herein, we summarize the recent advances made in the designing of DNA nanostructures with special emphasis on their application in biomedical research as imaging and diagnostic platforms, drug, gene, and protein vehicles, as well as theranostic agents that are meant to operate in-cell and in-vivo.

scholarly journals Cardiac pathologies in mouse loss of imprinting models are due to misexpression of H19 long noncoding RNA

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Ki-Sun Park ◽  
Beenish Rahat ◽  
Hyung Chul Lee ◽  
Zu-Xi Yu ◽  
Jacob Noeker ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Ventricular Function ◽  
Mouse Models ◽  
Long Noncoding Rna ◽  
Noncoding Rna ◽  
Relative Importance ◽  
Maternal Loss ◽  
Loss Of Imprinting

Maternal loss of imprinting (LOI) at the H19/IGF2 locus results in biallelic IGF2 and reduced H19 expression and is associated with Beckwith-Wiedemann syndrome (BWS). We use mouse models for LOI to understand the relative importance of Igf2 and H19 mis-expression in BWS phenotypes. Here we focus on cardiovascular phenotypes and show that neonatal cardiomegaly is exclusively dependent on increased Igf2. Circulating IGF2 binds cardiomyocyte receptors to hyperactivate mTOR signaling, resulting in cellular hyperplasia and hypertrophy. These Igf2-dependent phenotypes are transient: cardiac size returns to normal once Igf2 expression is suppressed postnatally. However, reduced H19 expression is sufficient to cause progressive heart pathologies including fibrosis and reduced ventricular function. In the heart, H19 expression is primarily in endothelial cells (ECs) and regulates EC differentiation both, in vivo and in vitro. Finally, we establish novel mouse models to show that cardiac phenotypes depend on H19 lncRNA interactions with Mirlet7 microRNAs.

scholarly journals Rumen degradation and fractional outflow rates of nitrogen supplements given to cattle eating sodium hydroxide-treated straw

1986 ◽  
Vol 55 (2) ◽  
pp. 387-398 ◽  
Author(s):  
K. Amaning-Kwarteng ◽  
R. C. Kellaway ◽  
Jane Leibholz ◽  
A. C. Kirby
Keyword(s):  
Sodium Hydroxide ◽  
Cotton Seed ◽  
Relative Importance ◽  
High Intake ◽  
Protein Supplements ◽  
Rumen Degradation ◽  
Cotton Seed Meal ◽  
Meat Meal ◽  
The Difference

1. Six rumen and abomasal cannulated heifers were used to study the effects of intake on the fractional outflow rates (FOR) of chromium-mordanted cotton-seed meal (Cr-CSM) and meat meal (Cr-MM), CrEDTA, ytterbium and lignin from the rumen. Values of FOR of Cr-CSM and Cr-MM were combined with values of nitrogen disappearance from the protein supplements, placed in porous synthetic (nylon) bags and incubated within the rumen (P), to calculate effective degradation (D)of CSM and MM when fed to heifers eating sodium hydroxide-treated straw. Also, N degradation in vivo (V) was measured as the difference between abomasal N flow and the sum of flows of microbial and endogenous N.2. FOR were positively related to intake and differences between supplements were significant (p<0.01). FOR pertaining to high and low intakes respectively were 0.073 and 0.052 for Cr-CSM, 0.082 and 0.071 for Cr-MM, 0.030 and 0.023 for lignin, 0.082 and 0.073 for CrEDTA and 0, 044 and 0.035 for Yb.3. A rise of 28.8 and 13.4% in FOR of Cr-CSM and Cr-MM respectively, associated with an increase in intake from maintenance to 1.5 times maintenance, resulted in 10.7 and 2.2% reductions inD, 24 h after feeding, for CSM and MM respectively.4. With the exception of CSM at the high intake, estimates ofVwere underestimated byDand were 8.6–25.0% greater than theDvalues when time of incubation (t)= ∞. The two techniques, however, ranked the degradation of the two supplements in the same order at both levels of intake.5. Underestimation ofVbyDmay be attributable to underestimation ofP, overestimation of FOR (both resulting in underestimation ofD) or overestimation ofVdue to biases associated with the estimation of this part of the comparison. The relative importance of these factors remains to be determined.

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