hollow structure
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- MeSH
- parodont anatomie a histologie fyziologie MeSH
- psi MeSH
- zuby anatomie a histologie fyziologie MeSH
- zvířata MeSH
- Check Tag
- psi MeSH
- zvířata MeSH
Polyacrylonitrile (PAN) membranes have been prepared using needleless electrospinning with wire electrode and characterized by a series of methods HRSEM, XRD, air permeability and area weight measurements in dependence of high voltage and electrode distance. HRSEM analysis revealed the tendency to longitudinal rolling of strip-shaped PAN fibers forming hollow fibers. Combination of XRD analysis and molecular modeling explains this phenomenon as the consequence of the specific crystal structure of PAN fibers, where the isotactic PAN chains are arranged in layers forming belt shaped nanofibers with the strong tendency to roll up longitudinally forming hollow fibers. This effect offers the possibility to create hollow nanofibers by electrospinning with the appropriate choice of structure of polymer chains.
Cytokinin ribosides (N(6)-substituted adenosine derivatives) have been shown to have anticancer activity both in vitro and in vivo. This study presents the first systematic analysis of the relationship between the chemical structure of cytokinins and their cytotoxic effects against a panel of human cancer cell lines with diverse histopathological origins. The results confirm the cytotoxic activity of N(6)-isopentenyladenosine, kinetin riboside, and N(6)-benzyladenosine and show that the spectrum of cell lines that are sensitive to these compounds and their tissues of origin are wider than previously reported. The first evidence that the hydroxylated aromatic cytokinins (ortho-, meta-, para-topolin riboside) and the isoprenoid cytokinin cis-zeatin riboside have cytotoxic activities is presented. Most cell lines in the panel showed greatest sensitivity to ortho-topolin riboside (IC(50)=0.5-11.6 microM). Cytokinin nucleotides, some synthesized for the first time in this study, were usually active in a similar concentration range to the corresponding ribosides. However, cytokinin free bases, 2-methylthio derivatives and both O- and N-glucosides showed little or no toxicity. Overall the study shows that structural requirements for cytotoxic activity of cytokinins against human cancer cell lines differ from the requirements for their activity in plant bioassays. The potent anticancer activity of ortho-topolin riboside (GI(50)=0.07-84.60 microM, 1st quartile=0.33 microM, median=0.65 microM, 3rd quartile=1.94 microM) was confirmed using NCI(60), a standard panel of 59 cell lines, originating from nine different tissues. Further, the activity pattern of oTR was distinctly different from those of standard anticancer drugs, suggesting that it has a unique mechanism of activity. In comparison with standard drugs, oTR showed exceptional cytotoxic activity against NCI(60) cell lines with a mutated p53 tumour suppressor gene. oTR also exhibited significant anticancer activity against several tumour models in in vivo hollow fibre assays.
- MeSH
- adenosin analogy a deriváty chemie farmakologie MeSH
- cytokininy analýza chemie metabolismus MeSH
- geny p53 účinky léků genetika MeSH
- inhibiční koncentrace 50 MeSH
- isopentenyladenosin analogy a deriváty chemie farmakologie MeSH
- kinetin chemie farmakologie MeSH
- lidé MeSH
- molekulární struktura MeSH
- National Cancer Institute (U.S.) MeSH
- protinádorové látky chemie farmakologie MeSH
- regulátory růstu rostlin farmakologie MeSH
- screeningové testy protinádorových léčiv MeSH
- stereoizomerie MeSH
- vztahy mezi strukturou a aktivitou MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Spojené státy americké MeSH
OBJECTIVE: The goal of this study was to determine the cause of selected canine urolith formation using less conventional but more advanced analytical methods. METHODS: A routine laboratory specialising in urinary calculi analysis noticed a special type of core zone in some canine uroliths, which was typically made up of cylindrical holes. Of 4028 canine samples analysed, non-absorbable suture material was detected in 9 (0·22%) cases. A hollow cylindrical central area was found in a further 13 (0·32%) samples. X-ray microtomography (μCT) was utilised in order to reveal the channel structure inside this urolith sample. Matrix-assisted laser desorption-ionisation - time of flight mass spectrometry was used in order to assess the cause of this urinary stone formation. RESULTS: The diameter of the channel structure corresponded with the diameter of the previously utilised suture material and indicated that this urolith was formed around residual suture material. Further confirmation was provided by the comparative matrix-assisted laser desorption-ionisation - time of flight mass spectrometry chemical analysis. This channel structure is formed by a surgical thread that serves as a base for the urolith growth. CLINICAL SIGNIFICANCE: Results of this study confirm the causative role of absorbable suture material in the pathogenesis of hollow channel structures in some canine compound uroliths.
- MeSH
- močové kameny etiologie veterinární MeSH
- nemoci psů etiologie MeSH
- psi MeSH
- spektrometrie hmotnostní - ionizace laserem za účasti matrice veterinární MeSH
- tomografie rentgenová veterinární MeSH
- urolitiáza etiologie veterinární MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- psi MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Here we provide a review on TldD/TldE family proteins, summarizing current knowledge and outlining further research perspectives. Despite being widely distributed in bacteria and archaea, TldD/TldE proteins have been escaping attention for a long time until several recent reports pointed to their unique features. Specifically, TldD/TldE generally act as peptidases, though some of them turned out to be N-deacetylases. Biological function of TldD/TldE has been extensively described in bacterial specialized metabolism, in which they participate in the biosynthesis of lincosamide antibiotics (as N-deacetylases), and in the biosynthesis of ribosomally synthesized and post-translationally modified bioactive peptides (as peptidases). These enzymes possess special position in the relevant biosynthesis since they convert non-bioactive intermediates into bioactive metabolites. Further, based on a recent study of Escherichia coli TldD/TldE, these heterodimeric metallopeptidases possess a new protein fold exhibiting several structural features with no precedent in the Protein Data Bank. The most interesting ones are structural elements forming metal-containing active site on the inner surface of the catalytically active subunit TldD, in which substrates bind through β sheet interactions in the sequence-independent manner. It results in relaxed substrate specificity of TldD/TldE, which is counterbalanced by enclosing the active centre within the hollow core of the heterodimer and only appropriate substrates can entry through a narrow channel. Based on the published data, we hypothesize a yet unrecognized central metabolic function of TldD/TldE in the degradation of (partially) unfolded proteins, i.e., in protein quality control.
... Multiple Clip Appliers 28 -- Skin Staplers 29 -- 3 Basic Stapling Techniques -- Terminal Closure of Hollow ... ... of Incisions 31 -- End-to-end Anastomosis: Triangulation Technique. 32 -- Transection of Tubular Structure ... ... and Hollow Organs 33 -- Creation of Side-to-side (Enterocolostomy) Anastomosis 34 -- Functional End-to-end ...
294 s. : il. ; 30 cm + 1 CD-ROM
- MeSH
- chirurgická technika pomocí přístrojů a svorek klasifikace metody MeSH
- chirurgie MeSH
- Publikační typ
- atlasy MeSH
- Konspekt
- Ortopedie. Chirurgie. Oftalmologie
- NLK Obory
- chirurgie
Nanomedicine as a continuously evolving discipline is still looking for a structure with perfect properties that is usable as a multifunctional transporter. Great potential is attributed to synthetic materials such as fullerenes, porous hollow silica nanoparticles and single-wall nanotubes, among others. However, materials that are natural to the human body are more acceptable by the organism, and thus become an attractive approach in this field of research. Ferritins are proteins that naturally occur in most living organisms throughout evolution and may be a possible transporter choice. Numerous applications have demonstrated the possibilities of iron-free ferritins, called apoferritins, serving as platforms for various nanomedical purposes This article summarizes the advantages and disadvantages of these proteins and discusses their practical applications and future perspectives.
Recently, porous carriers are used in the pharmaceuti-cal technology due to their promising properties ‒ large specific surface area, porous structure, suitable technologi-cal properties, etc. They participate in the preparation of liquisolid systems, self-emulsifying drug delivery systems, etc., which are capable to deliver and release the drug in the required manner to the biological system. One of the most widely used porous carrier is microcrystalline cellu-lose. Other perspective carriers are magnesium alumi-nometasilicates, which show several advantageous proper-ties. Also calcium hydrogen phosphate represents a com-monly used carrier with easy compressibility, rapid disin-tegration or improved flow properties. Due to their large specific surface area, mesoporous silicates and silica aero-gels are also often used. The clay materials in the form of natural or modified materials with a structure of hollow nanotubes provide a suitable carrier of the drug. This arti-cle summarizes basic information about available porous carriers and their characterizations, as well as available application studies on the given topic.
This work is focused on preparation of novel porous type of core-shell-structured microparticles based on polylactide (shell) and poly(vinyl alcohol) cross-linked with glutaric acid (GA) (core) prepared by water-in-oil-in-water solvent evaporation technique. The microparticle systems were used as delivery systems for immobilisation of model antibacterial agent - nisin. The effect of cross-linking and the initial amount of nisin on their morphology was investigated using scanning electron microscopy, BET analysis, zeta potential measurement and Fourier transform infra-red spectroscopy. Encapsulation efficiency and release profile of nisin from the microparticles were studied by high performance liquid chromatography. Antibacterial activity of the prepared systems was tested by dilution and spread plate technique. Results showed the microparticles in the size range of 9-16 μm in diameter with spherical multi-hollow core-shell structure. The presence of cross-linking agent GA influences the release profile of the peptide and has synergistic effect on Listeria monocytogenes growth reduction.
- MeSH
- antibakteriální látky aplikace a dávkování MeSH
- glutaráty chemie MeSH
- Listeria monocytogenes účinky léků MeSH
- mikroskopie elektronová rastrovací MeSH
- nisin aplikace a dávkování MeSH
- nosiče léků chemie MeSH
- polyestery chemie MeSH
- polyvinylalkohol chemie MeSH
- poréznost MeSH
- velikost částic MeSH
- Publikační typ
- časopisecké články MeSH
Monogeneans rely on firm attachment to often flexible and uneven surfaces and are renowned for their effective posterior attachment structures in the form of adhesives, clamps, hamuli and suckers. Polystomatids do not secrete adhesives and do not have clamps. While only some have hamuli, all have suckers in the adult form. Three different types of haptoral suckers have been described based on basic morphology but have never been studied in depth. Using enzyme digestion and light (differential interference contrast), confocal and scanning electron microscopy, we examined representatives and propose four sucker types. Haptoral sucker Type I are symmetrical soft, flexible, cup- to disk-shaped suckers and are found in all polystomes infecting frogs and salamanders. Type II suckers are symmetrical soft, flexible, cup-shaped suckers with a hollow continuous skeletal ring and no other skeletal elements. They are found in species of Nanopolystoma Du Preez, Wilkinson et Huyse, 2008 infecting caecilians. Type III suckers are symmetrical firm, cup-shaped suckers with elaborate skeletal elements that contribute to a secure grip on the host tissue. This type of sucker is found in all polystomes infecting freshwater turtles and the common hippopotamus. Type IV suckers are asymmetrical with an elaborate series of long, thin sclerites with terminal spines or hooks. This type of sucker is only known from Concinnocotyla australensis (Reichenbach-Klinke, 1966) infecting the Australian lungfish. These different sucker types are crucial for the survival of polystomatid flatworms within their respective microhabitats.
- MeSH
- mikroskopie elektronová rastrovací MeSH
- Trematoda * anatomie a histologie klasifikace MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
