Use of light microscopy in the qualitative and quantitative study of liquid crystalline order

1992 ◽  
Vol 50 (1) ◽  
pp. 264-265
Author(s):  
Christopher Viney
Keyword(s):  
Light Microscopy ◽  
Liquid Crystalline ◽  
Structural Characteristics ◽  
Molecular Order ◽  
Liquid Crystalline Phases ◽  
Convenient Technique ◽  
Liquid Crystalline Materials ◽  
Transparent Windows

Light microscopy is a convenient technique for characterizing molecular order in fluid liquid crystalline materials. Microstructures can usually be observed under the actual conditions that promote the formation of liquid crystalline phases, whether or not a solvent is required, and at temperatures that can range from the boiling point of nitrogen to 600°C. It is relatively easy to produce specimens that are sufficiently thin and flat, simply by confining a droplet between glass cover slides. Specimens do not need to be conducting, and they do not have to be maintained in a vacuum. Drybox or other controlled environmental conditions can be maintained in a sealed chamber equipped with transparent windows; some heating/ freezing stages can be used for this purpose. It is relatively easy to construct a modified stage so that the generation and relaxation of global molecular order can be observed while specimens are being sheared, simulating flow conditions that exist during processing. Also, light only rarely affects the chemical composition or molecular weight distribution of the sample. Because little or no processing is required after collecting the sample, one can be confident that biologically derived materials will reveal many of their in vivo structural characteristics, even though microscopy is performed in vitro.

Liquid crystalline phases of monoolein and water for topical delivery of cyclosporin A: Characterization and study of in vitro and in vivo delivery

2006 ◽  
Vol 63 (2) ◽  
pp. 146-155 ◽  
Author(s):  
Luciana B. Lopes ◽  
João L.C. Lopes ◽  
Dionéia C.R. Oliveira ◽  
José A. Thomazini ◽  
M. Tereza J. Garcia ◽  
...  
Keyword(s):  
Cyclosporin A ◽  
Liquid Crystalline ◽  
Topical Delivery ◽  
Crystalline Phases ◽  
Liquid Crystalline Phases ◽  
In Vivo Delivery

Invite Article: The Liquid-Crystalline Phases of Double-Stranded Nucleic Acids in Vitro and in Vivo

1988 ◽  
Vol 3 (11) ◽  
pp. 1443-1459 ◽  
Author(s):  
Yu M. Yevdokimov ◽  
S. G. Skuridin ◽  
V. I. Salyanov
Keyword(s):  
Nucleic Acids ◽  
Liquid Crystalline ◽  
Crystalline Phases ◽  
Liquid Crystalline Phases

Molecular Order in Silk Secretions

1991 ◽  
Vol 248 ◽  
Author(s):  
Christopher Viney ◽  
Keven Kerkam ◽  
Lisa Gilliland ◽  
David Kaplan ◽  
Stephen Fossey
Keyword(s):  
Liquid Crystalline ◽  
Polarized Light ◽  
Amino Acid Sequences ◽  
Silk Proteins ◽  
Secondary Structure Analysis ◽  
Liquid Crystalline Phases ◽  
Strength And Stiffness ◽  
Supramolecular Aggregates

AbstractTransmitted polarized light microscopy of various natural silk secretions reveals their ability to form nematic liquid crystalline phases. Observations of microstructure, together with a simple secondary structure analysis of known amino acid sequences in silk proteins, suggest that the rodlike structures forming the nematic phase are supramolecular aggregates, rather than individual rigid molecular segments. The optical birefringence of dragline fiber produced by controlled silking depends on the linear haul-off velocity, and can exceed the birefringence of naturally spun fibers; this suggests the possibility of in-vitro spinning of silk to obtain values of strength and stiffness even greater than those achieved in vivo.

scholarly journals Recent Developments in Inonotus obliquus (Chaga mushroom) Polysaccharides: Isolation, Structural Characteristics, Biological Activities and Application

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1441
Author(s):  
Yangpeng Lu ◽  
Yanan Jia ◽  
Zihan Xue ◽  
Nannan Li ◽  
Junyu Liu ◽  
...  
Keyword(s):  
Biological Activities ◽  
Structural Characteristics ◽  
Potential Candidate ◽  
Health Food ◽  
Inonotus Obliquus ◽  
Recent Developments ◽  
Inonotus Obliquus Polysaccharide ◽  
Future Work

Inonotus obliquus (Chaga mushroom) is a kind of medicine and health food widely used by folk in China, Russia, Korea, and some occidental countries. Among the extracts from Inonotus obliquus, Inonotus obliquus polysaccharide (IOPS) is supposed to be one of the major bioactive components in Inonotus obliquus, which possesses antitumor, antioxidant, anti-virus, hypoglycemic, and hypolipidemic activities. In this review, the current advancements on extraction, purification, structural characteristics, and biological activities of IOPS were summarized. This review can provide significant insight into the IOPS bioactivities as their in vitro and in vivo data were summarized, and some possible mechanisms were listed. Furthermore, applications of IOPS were reviewed and discussed; IOPS might be a potential candidate for the treatment of cancers and type 2 diabetes. Besides, new perspectives for the future work of IOPS were also proposed.

scholarly journals The State of the Art and Prospects for Osteoimmunomodulatory Biomaterials

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1357
Author(s):  
Andreea-Mariana Negrescu ◽  
Anisoara Cimpean
Keyword(s):  
Foreign Bodies ◽  
Structural Characteristics ◽  
Critical Role ◽  
Fibrous Tissue ◽  
Bioactive Molecules ◽  
New Bone Formation ◽  
Recent Developments

The critical role of the immune system in host defense against foreign bodies and pathogens has been long recognized. With the introduction of a new field of research called osteoimmunology, the crosstalk between the immune and bone-forming cells has been studied more thoroughly, leading to the conclusion that the two systems are intimately connected through various cytokines, signaling molecules, transcription factors and receptors. The host immune reaction triggered by biomaterial implantation determines the in vivo fate of the implant, either in new bone formation or in fibrous tissue encapsulation. The traditional biomaterial design consisted in fabricating inert biomaterials capable of stimulating osteogenesis; however, inconsistencies between the in vitro and in vivo results were reported. This led to a shift in the development of biomaterials towards implants with osteoimmunomodulatory properties. By endowing the orthopedic biomaterials with favorable osteoimmunomodulatory properties, a desired immune response can be triggered in order to obtain a proper bone regeneration process. In this context, various approaches, such as the modification of chemical/structural characteristics or the incorporation of bioactive molecules, have been employed in order to modulate the crosstalk with the immune cells. The current review provides an overview of recent developments in such applied strategies.

scholarly journals An integrated approach to unravel a crucial structural property required for the function of the insect steroidogenic Halloween protein Noppera-bo

2020 ◽  
Vol 295 (20) ◽  
pp. 7154-7167 ◽  
Author(s):  
Kotaro Koiwai ◽  
Kazue Inaba ◽  
Kana Morohashi ◽  
Sora Enya ◽  
Reina Arai ◽  
...  
Keyword(s):  
Structural Characteristics ◽  
Integrated Approach ◽  
Binding Pocket ◽  
Loss Of Function ◽  
Tertiary Structures ◽  
Ecdysteroid Biosynthesis ◽  
17Β Estradiol ◽  
Unique Amino Acid

Ecdysteroids are the principal steroid hormones essential for insect development and physiology. In the last 18 years, several enzymes responsible for ecdysteroid biosynthesis encoded by Halloween genes were identified and genetically and biochemically characterized. However, the tertiary structures of these proteins have not yet been characterized. Here, we report the results of an integrated series of in silico, in vitro, and in vivo analyses of the Halloween GST protein Noppera-bo (Nobo). We determined crystal structures of Drosophila melanogaster Nobo (DmNobo) complexed with GSH and 17β-estradiol, a DmNobo inhibitor. 17β-Estradiol almost fully occupied the putative ligand-binding pocket and a prominent hydrogen bond formed between 17β-estradiol and Asp-113 of DmNobo. We found that Asp-113 is essential for 17β-estradiol–mediated inhibition of DmNobo enzymatic activity, as 17β-estradiol did not inhibit and physically interacted less with the D113A DmNobo variant. Asp-113 is highly conserved among Nobo proteins, but not among other GSTs, implying that this residue is important for endogenous Nobo function. Indeed, a homozygous nobo allele with the D113A substitution exhibited embryonic lethality and an undifferentiated cuticle structure, a phenocopy of complete loss-of-function nobo homozygotes. These results suggest that the nobo family of GST proteins has acquired a unique amino acid residue that appears to be essential for binding an endogenous sterol substrate to regulate ecdysteroid biosynthesis. To the best of our knowledge, ours is the first study describing the structural characteristics of insect steroidogenic Halloween proteins. Our findings provide insights relevant for applied entomology to develop insecticides that specifically inhibit ecdysteroid biosynthesis.

scholarly journals Drug reformulation for a neglected disease. The NANOHAT project to develop a safer more effective sleeping sickness drug

2021 ◽  
Vol 15 (4) ◽  
pp. e0009276
Author(s):  
Lisa Sanderson ◽  
Marcelo da Silva ◽  
Gayathri N. Sekhar ◽  
Rachel C. Brown ◽  
Hollie Burrell-Saward ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Structural Characteristics ◽  
Research Programme ◽  
Inhibitory Effect ◽  
Sleeping Sickness ◽  
Tsetse Fly ◽  
Neglected Diseases ◽  
Target Candidate Profile

Background Human African trypanosomiasis (HAT or sleeping sickness) is caused by the parasite Trypanosoma brucei sspp. The disease has two stages, a haemolymphatic stage after the bite of an infected tsetse fly, followed by a central nervous system stage where the parasite penetrates the brain, causing death if untreated. Treatment is stage-specific, due to the blood-brain barrier, with less toxic drugs such as pentamidine used to treat stage 1. The objective of our research programme was to develop an intravenous formulation of pentamidine which increases CNS exposure by some 10–100 fold, leading to efficacy against a model of stage 2 HAT. This target candidate profile is in line with drugs for neglected diseases inititative recommendations. Methodology To do this, we evaluated the physicochemical and structural characteristics of formulations of pentamidine with Pluronic micelles (triblock-copolymers of polyethylene-oxide and polypropylene oxide), selected candidates for efficacy and toxicity evaluation in vitro, quantified pentamidine CNS delivery of a sub-set of formulations in vitro and in vivo, and progressed one pentamidine-Pluronic formulation for further evaluation using an in vivo single dose brain penetration study. Principal Findings Screening pentamidine against 40 CNS targets did not reveal any major neurotoxicity concerns, however, pentamidine had a high affinity for the imidazoline2 receptor. The reduction in insulin secretion in MIN6 β-cells by pentamidine may be secondary to pentamidine-mediated activation of β-cell imidazoline receptors and impairment of cell viability. Pluronic F68 (0.01%w/v)-pentamidine formulation had a similar inhibitory effect on insulin secretion as pentamidine alone and an additive trypanocidal effect in vitro. However, all Pluronics tested (P85, P105 and F68) did not significantly enhance brain exposure of pentamidine. Significance These results are relevant to further developing block-copolymers as nanocarriers, improving BBB drug penetration and understanding the side effects of pentamidine.

scholarly journals The Natural Compound Hydrophobic Usnic Acid and Hydrophilic Potassium Usnate Derivative: Applications and Comparisons

Molecules ◽  
2021 ◽  
Vol 26 (19) ◽  
pp. 5995
Author(s):  
Hallysson Douglas Andrade de Araújo ◽  
Hianna Arely Milca Fagundes Silva ◽  
José Guedes da Silva Júnior ◽  
Mônica Camelo Pessoa de Azevedo Albuquerque ◽  
Luana Cassandra Breitenbach Barroso Coelho ◽  
...  
Keyword(s):  
Biological Activities ◽  
Structural Characteristics ◽  
Usnic Acid ◽  
Raw Material ◽  
Structural Modifications ◽  
Hydrophobic Molecule ◽  
Antiparasitic Agents ◽  
Toxic Molecule

Usnic acid is the best-studied lichen metabolite, presenting several biological activities, such as antibacterial, immunostimulating, antiviral, antifungal, anti-inflammatory, and antiparasitic agents; despite these relevant properties, it is a hydrophobic and toxic molecule. In this context, scientific research has driven the development of innovative alternatives, considering usnic acid as a source of raw material in obtaining new molecules, allowing structural modifications (syntheses) from it. The purpose is to optimize biological activities and toxicity, with less concentration and/or response time. This work presents a literature review with an analogy of the hydrophobic molecule of usnic acid with its hydrophilic derivative of potassium usnate, emphasizing the elucidation and structural characteristics, biological activities, and toxicological aspects of both molecules, and the advantages of using the promising derivative hydrophilic in different in vitro and in vivo assays when compared to usnic acid.

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