The hop metabolome important for the brewing industry and for medical purposes is endangered worldwide due to multiple viroid infections affecting hop physiology. Combinatorial biolistic hop inoculation with Citrus bark cracking viroid (CBCVd), Apple fruit crinkle viroid (AFCVd), Hop latent viroid, and Hop stunt viroid (HSVd) showed a low CBCVd compatibility with HSVd, while all other viroid combinations were highly compatible. Unlike to other viroids, single CBCVd propagation showed a significant excess of (-) over (+) strands in hop, tomato, and Nicotiana benthamiana, but not in citruses. Inoculation of hop with all viroids led to multiple infections with unstable viroid levels in individual plants in the pre- and post-dormancy periods, and to high plant mortality and morphological disorders. Hop isolates of CBCVd and AFCVd were highly stable, only minor quasispecies were detected. CBCVd caused a strong suppression of some crucial mRNAs related to the hop prenylflavonoid biosynthesis pathway, while AFCVd-caused effects were moderate. According to mRNA degradome analysis, this suppression was not caused by a direct viroid-specific small RNA-mediated degradation. CBCVd infection led to a strong induction of two hop transcription factors from WRKY family and to a disbalance of WRKY/WDR1 complexes important for activation of lupulin genes.
- MeSH
- Citrus genetics virology MeSH
- Humulus genetics virology MeSH
- Real-Time Polymerase Chain Reaction MeSH
- Malus genetics virology MeSH
- RNA, Messenger genetics MeSH
- Fruit genetics virology MeSH
- Nicotiana genetics virology MeSH
- Viroids genetics pathogenicity MeSH
- Publication type
- Journal Article MeSH
Some viroids-single-stranded, non-coding, circular RNA parasites of plants-are not transmissible through pollen to seeds and to next generation. We analyzed the cause for the elimination of apple fruit crinkle viroid (AFCVd) and citrus bark cracking viroid (CBCVd) from male gametophyte cells of Nicotiana tabacum by RNA deep sequencing and molecular methods using infected and transformed tobacco pollen tissues at different developmental stages. AFCVd was not transferable from pollen to seeds in reciprocal pollinations, due to a complete viroid eradication during the last steps of pollen development and fertilization. In pollen, the viroid replication pathway proceeds with detectable replication intermediates, but is dramatically depressed in comparison to leaves. Specific and unspecific viroid degradation with some preference for (-) chains occurred in pollen, as detected by analysis of viroid-derived small RNAs, by quantification of viroid levels and by detection of viroid degradation products forming "comets" on Northern blots. The decrease of viroid levels during pollen development correlated with mRNA accumulation of several RNA-degrading factors, such as AGO5 nuclease, DICER-like and TUDOR S-like nuclease. In addition, the functional status of pollen, as a tissue with high ribosome content, could play a role during suppression of AFCVd replication involving transcription factors IIIA and ribosomal protein L5.
Viroids are smallest known pathogen that consist of non-capsidated, single-stranded non-coding RNA replicons and they exploits host factors for their replication and propagation. The severe stunting disease caused by Citrus bark cracking viroid (CBCVd) is a serious threat, which spreads rapidly within hop gardens. In this study, we employed comprehensive transcriptome analyses to dissect host-viroid interactions and identify gene expression changes that are associated with disease development in hop. Our analysis revealed that CBCVd-infection resulted in the massive modulation of activity of over 2000 genes. Expression of genes associated with plant immune responses (protein kinase and mitogen-activated protein kinase), hypersensitive responses, phytohormone signaling pathways, photosynthesis, pigment metabolism, protein metabolism, sugar metabolism, and modification, and others were altered, which could be attributed to systemic symptom development upon CBCVd-infection in hop. In addition, genes encoding RNA-dependent RNA polymerase, pathogenesis-related protein, chitinase, as well as those related to basal defense responses were up-regulated. The expression levels of several genes identified from RNA sequencing analysis were confirmed by qRT-PCR. Our systematic comprehensive CBCVd-responsive transcriptome analysis provides a better understanding and insights into complex viroid-hop plant interaction. This information will assist further in the development of future measures for the prevention of CBCVd spread in hop fields.
- MeSH
- Humulus genetics metabolism virology MeSH
- Plant Leaves genetics metabolism virology MeSH
- Plant Diseases genetics virology MeSH
- Gene Expression Regulation, Plant MeSH
- Plant Proteins genetics metabolism MeSH
- Plant Viruses genetics isolation & purification physiology MeSH
- Gene Expression Profiling MeSH
- Viroids classification genetics isolation & purification physiology MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Aortic dissection is a life-threatening disease that consists in the development of a tear in the wall of the aorta. The initial tear propagates as a discontinuity leading to separation within the aortic wall, which can result in the creation of a so-called false lumen. A fatal threat occurs if the rupture extends through the whole thickness of the aortic wall, as blood may then leak. It is generally accepted that the dissection, which can sometime extend along the entire length of the aorta, propagates via a delamination mechanism. The aim of the present paper is to provide experimentally validated parameters of a mathematical model for the description of the wall's cohesion. A model of the peeling experiment was built in Abaqus. The delamination interface was described by a piecewise linear traction-separation law. The bulk behavior of the aorta was assumed to be nonlinearly elastic, anisotropic, and incompressible. Our simulations resulted in estimates of the material parameters for the traction-separation law of the human descending thoracic aorta, which were obtained by minimizing the differences between the FEM predictions and the delamination force given by the regression of the peeling experiments. The results show that the stress at damage initiation, Tc, should be understood as an age-dependent quantity, and under the assumptions of our model this dependence can be expressed by linear regression as Tc = - 13.03·10-4·Age + 0.2485 if the crack front advances in the axial direction, and Tc = - 7.58·10-4·Age + 0.1897 if the crack front advances in the direction of the aortic circumference (Tc [MPa], Age [years]). Other model parameters were the stiffness K and the separation at failure, δf-δc (K = 0.5 MPa/mm, δf-δc = 0.1 mm). The material parameters provided by our study can be used in numerical simulations of the biomechanics of dissection propagation through the aorta especially when age-associated phenomena are studied.
- MeSH
- Finite Element Analysis MeSH
- Aorta, Thoracic * physiology MeSH
- Biomechanical Phenomena MeSH
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Stress, Mechanical MeSH
- Models, Cardiovascular MeSH
- Computer Simulation MeSH
- Aged MeSH
- Aging physiology MeSH
- Traction MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Aged MeSH
- Publication type
- Journal Article MeSH
OBJECTIVES: Ultra-high-speed (UHS) videography was used to visualize the fracture phenomena at the resin-dentin interface during micro-tensile bond strength (μTBS) test. We also investigated whether UHS videography is applicable for failure-mode analysis. METHODS: Ten human mid-coronal dentin surfaces were bonded using Clearfil SE Bond either in self-etching (SE) or etch-and-rinse (ER) mode. After 24-h water storage, the samples were cut into beams for μTBS test and tested at a cross-head speed of 1 mm/min. The fracture phenomena at the bonded interface were captured using a complementary metal-oxide-semiconductor digital UHS camera at 299,166 frames per second. The failure modes were classified using UHS videography, followed by scanning electron microscopy (SEM) analysis. The failure-mode distributions determined by UHS videography and SEM analysis were statistically analyzed using Fisher's exact test with Bonferroni correction. RESULTS: The crack-propagation speed exceeded 1,500 km/h. No significant difference was found between the SEM and UHS videography failure-mode distributions in the SE mode. A significant difference appeared between them in the ER mode. Significant differences in the incidence of cohesive failures within the adhesive and at the adhesive-composite interface between the SE and ER modes were identified by both SEM and UHS videography. SIGNIFICANCE: UHS videography enabled visualization of the fracture dynamics at the resin- dentin interfaces under tensile load. However, the resolution at such high frame rate was insufficient to classify the failure mode as precisely as that of SEM. Nevertheless, UHS videography can provide more detailed information about the fracture origin and propagation.
- MeSH
- Dentin MeSH
- Dentin-Bonding Agents * MeSH
- Humans MeSH
- Stress, Mechanical MeSH
- Microscopy, Electron, Scanning MeSH
- Tensile Strength MeSH
- Surface Properties MeSH
- Resin Cements MeSH
- Composite Resins MeSH
- Materials Testing MeSH
- Dental Bonding * MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Aortic dissection is a biomechanical phenomenon associated with a failure of internal cohesion, which manifests itself through the delamination of the aortic wall. The goal of this study is to deepen our knowledge of the delamination strength of the aorta. To achieve this, 661 peeling experiments were carried out with strips of the human aorta collected from 46 cadavers. The samples were ordered into groups with respect to (1) anatomical location, (2) orientation of the sample, and (3) extension rate used within the experiment. The obtained results are in accordance with the hypothesis that delamination resistance is not sensitive to the extension rates 0.1, 1, 10, and 50 mms-1. We arrived at this conclusion for all positions along the aorta investigated in our study. These were the thoracic ascending (AAs), thoracic descending (ADs), and the abdominal aorta (AAb), simultaneously considering both the longitudinal (L) as well as the circumferential (C) orientations of the samples. On the other hand, our results showed that the delamination strength differs significantly with respect to the anatomical position and orientation of the sample. The medians of the delamination strength were as follows, 4.1 in AAs-L, 3.2 in AAs-C, 3.1 in ADs-L, 2.4 in ADs-C, AAb-L in 3.6, and 2.7 in AAb-C case (all values are in 0.01·Nmm-1). This suggests that resistance to crack propagation should be an anisotropic property and that the aorta is inhomogeneous along its length from the point of view of delamination resistance. Finally, correlation analysis proved that the delamination strength of the human aorta significantly decreases with age.
- MeSH
- Anisotropy MeSH
- Aorta, Abdominal MeSH
- Aorta, Thoracic MeSH
- Biomechanical Phenomena MeSH
- Aortic Dissection * MeSH
- Humans MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Blends of two biodegradable polymers, poly(lactic acid) (PLA) and poly(ϵ-caprolactone) (PCL), with strong synergistic improvement in mechanical performance were prepared by melt-mixing using the optimized composition (80/20) and the optimized preparation procedure (a melt-mixing followed by a compression molding) according to our previous study. Three different PLA polymers were employed, whose viscosity decreased in the following order: PLC ≈ PLA1 > PLA2 > PLA3. The blends with the highest viscosity matrix (PLA1/PCL) exhibited the smallest PCL particles (d∼0.6μm), an elastic-plastic stable fracture (as determined from instrumented impact testing) and the strongest synergistic improvement in toughness (>16× with respect to pure PLA, exceeding even the toughness of pure PCL). According to the available literature, this was the highest toughness improvement in non-compatiblized PLA/PCL blends ever achieved. The decrease in the matrix viscosity resulted in an increase in the average PCL particle size and a dramatic decrease in the overall toughness: the completely stable fracture (for PLA1/PCL) changed to the stable fracture followed by unstable crack propagation (for PLA2/PCL) and finally to the completely brittle fracture (for PLA3/PCL). The stiffness of all blends remained at well acceptable level, slightly above the theoretical predictions based on the equivalent box model. Despite several previous studies, the results confirmed that PLA and PCL could behave as compatible polymers, but the final PLA/PCL toughness is extremely sensitive to the PCL particle size distribution, which is influenced by both processing conditions and PLA viscosity. PLA/PCL blends with high stiffness (due to PLA) and toughness (due to PCL) are very promising materials for medical applications, namely for the bone tissue engineering.
- MeSH
- Polyesters analysis MeSH
- Polymers MeSH
- Viscosity * MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Although kidney trauma is a relatively common injury, its microscopic biomechanics are poorly understood. Experimental low-grade trauma in pig kidneys was studied using optical microscopy. We observed ruptures in the cortex as well as in the medulla. Both parts of the renal parenchyma were damaged, even in areas of the kidneys that were free of macroscopic cracks on the surface. To determine which constituents of the renal cortex and medulla, i.e. tubular parts of the nephron or the interstitial connective tissue, were less resistant to injury during the drop shatter test, we applied a simple stereological method to discriminate between random and tissue-specific rupture propagation. The ruptures propagated predominantly through the interstitial connective tissue of the renal cortex and medulla. The volume fraction of the tubules assessed by the Cavalieri principle was 90.4% within the renal cortex and 52.4% within the medulla. The most frequently affected blood vessels were the arcuate and interlobular veins, followed by the arcuate and interlobular arteries. No disruptions of the renal calyces were found.
- MeSH
- Renal Artery pathology MeSH
- Kidney Medulla blood supply pathology injuries MeSH
- Kidney Cortex blood supply pathology injuries MeSH
- Kidney Tubules pathology injuries MeSH
- Kidney pathology injuries MeSH
- Nephrons pathology MeSH
- Swine MeSH
- Renal Circulation MeSH
- Rupture pathology MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Research Support, Non-U.S. Gov't MeSH
Předmět sdělení: Keramika je směs jednoho nebo více kovových prvků s prvkem nekovovým, obvykle kyslíkem. Výsledkem je chemicky a biochemicky stabilní látka, která je tvrdá, pevná, křehká a termicky a elektricky nevodivá. Tyto její vlastnosti se využívají v zubním lékařství k výrobě keramických náhrad [14], a to od celokeramických nebo metalokeramických korunek a můstků, inlejí, onlejí, faset až po implantáty a jejich pilíře, a zuby určené pro výrobu snímatelných náhrad [15]. Dentální keramika je tvořena kombinací amorfního skla (pojivo) a keramických krystalů (plnivo), jejichž vzájemný poměr rozhoduje o finálních vlastnostech keramické náhrady [15]. Vlastnosti materiálu: Sklo je homogenní amorfní (netvoří krystalickou mřížku) pevná hmota, která vznikla následkem rychlého ochlazení taveniny, nejčastěji sklářského písku. Jeho hlavní složkou je oxid křemičitý SiO2 obohacený o přísady, jako je uhličitan sodný (soda) a uhličitan draselný (potaš) pro snížení teploty tavení a oxid vápenatý (pálené vápno) pro lepší chemickou odolnost. Při zvyšování objemu amorfního skla nabývá keramická struktura na transparenci, ale ztrácí svou mechanickou odolnost. Nekrystalické sklo je leptatelné kyselinou fluorovodíkovou, což umožní následnou adhezivní fixaci povrchu keramiky k tvrdým zubním tkáním [11, 15]. Krystaly (tvoří krystalickou mřížku) zlepšují mechanické vlastnosti amorfního skla. Mají funkci retardérů bránících propagaci praskliny a odlamování částí keramiky. Zvyšováním poměru pojiva a plniva ve prospěch krystalů ztrácí keramika transparentnost a nabývá na odolnosti [11]. Závěr: Znalost složení dentální keramiky, její mikrostruktury a vlastností, je rozhodující pro výběr vhodného keramického materiálu pro řešení konkrétních klinických situací. Tento přehledový článek shrnuje základní parametry skupin dentálních keramických materiálů. Celokeramické náhrady jsou velmi populární v každodenní praxi zubního lékaře. Jedná se o velmi spolehlivý materiál, který má vysoký estetický potenciál a zároveň příznivou mechanickou odolnost. Jeho dobrá prognóza při dodržení správného technologického postupu otevírá další možnosti použití.
Background: Ceramics is a mixture of one or more metallic components with a non-metallic element, usually oxygen. The result is a chemically and biochemically stable substance that is hard, firm, brittle and thermally and electrically non-conductive. These properties are used in dentistry to produce dental ceramic restorations [14]. From all-ceramic or metalloceramic crowns and bridges, inlays, onlays, veneers and implants and their abutments, and teeth intended to use with the removable dentures [15]. Dental ceramics consist of a combination of amorphous glass (binder) and ceramic crystals (filler), whose relative ratio determines the final properties of the ceramic restorations [15]. Material properties: The glass is a homogeneous amorphous (not a crystalline lattice) solid mass resulting from rapid cooling of the melt, most often glassy melting sand. Its main ingredient is silicon oxide (silica) SiO2, enriched with additives such as sodium carbonate (soda) and potassium carbonate to reduce melting temperature and calcium oxide (burnt lime) for better chemical resistance. By increasing the volume of amorphous glass, the ceramic structure gains transparency, but loses its mechanical resistance. The non-crystalline glass is etchable with hydrofluoric acid, allowing the subsequent adhesion of ceramic surface to hard tooth tissue [11, 15]. Conclusions: Crystals (forming a crystalline grid) improve the mechanical properties of amorphous glass. They have the function of retarders to prevent cracks propagation and breakage of parts of ceramics. By increasing the binder and filler ratio in favor of crystals, ceramics loses transparency and becomes more resistant [11]. The all-ceramic restorations are very popular in everyday dental practice. It is a very reliable material that has a high aesthetic potential and a favorable mechanical resistance. Its good prognosis, while adhering to the right technological process, opens up other options for its use.
- Keywords
- celokeramické náhrady, dentální keramika, živcová keramika, lithium disilikátová keramika, zirkoniová keramika,
- MeSH
- Ceramics * therapeutic use MeSH
- Humans MeSH
- Dental Cements therapeutic use MeSH
- Dental Materials * therapeutic use MeSH
- Dentures MeSH
- Check Tag
- Humans MeSH
- Publication type
- Review MeSH
