Public Health, Vol 2, Issue 1, Jan-Mar / Oral Biopsy in General Dental Practice: A DOI/ijmedph 2Dept of Oral Pathology & Microbiology. Oral Health for the Americas (“the Plan”) (Document CD47/14), adopted in through . Most country programs have integrated oral health care into. referred to as oral health indicators, and include dental caries experience, untreated dental decay, tooth removal FLUORIDATION OF WATER SUPPLIES.
Biodegradable poly D,L-lactic acid PLA50 nanoparticles coated with either a readily digestible protein, albumin, or a non-digestible polymer, polyvinyl alcohol, were prepared by the solvent evaporation technique.
PLA50 degradation was determined using size exclusion chromatography as well as the enzymatic detection of lactate in bulk solution. In pepsin-rich simulated gastric fluid, similar behaviour was observed for both nanoparticle systems: In pancreatin-rich simulated intestinal fluid, however, the degradation of the PLA50 matrix was different, depending on the agent coating the nanoparticles: Thus, a direct relationship between degradability of the coating agent and subsequent PLA50 degradation in simulated intestinal fluid was established.
Controlled vaccine release in the gut-associated lymphoid tissues. Orally administered biodegradable microspheres target the Peyer's patches. Microspheres prepared from various polymers were evaluated for their usefulness as carriers for the targeted delivery of vaccine antigens to the gut-associated lymphoid tissues.
Following oral administration to mice, microspheres consisting of polystyrene, poly methyl methacrylate , poly hydroxybutyrate , poly dl-lactide , poly l-lactide , and of poly dl-lactide-co-glycolide with various ratios of lactide to glycolide were absorbed into the Peyer's patches of the small intestine.
In contrast, no or very little uptake was observed with microspheres consisting of ethyl cellulose, cellulose acetate hydrogen phthalate or cellulose triacetate. Poly dl-lactide-co-glycolide microspheres containing a toxoid vaccine of staphylococcal enterotoxin B were prepared and characterized for their size distribution, surface morphology and toxoid release kinetics in an aqueous environment.
Oral immunization with these microspheres effectively delivered and released the vaccine in the gutassociated lymphoid tissue as determined by their ability to induce a disseminated mucosal IgA anti-toxin antibody response.
Nanoparticles as carriers for oral peptide absorption: Studies on particle uptake and fate. Previous work from our laboratories has provided quantitative proof of the importance of the gut associated lymphoid tissue GALT in the processes involved in the uptake of polystyrene nanoparticles delivered orally, and has confirmed the role of the Peyer's patches in the uptake of particles through the small intestine.
In more recent work discussed here the role of lymphoid tissue in the large intestine has been demonstrated, a significant amount of the total uptake occurring in this region of the gut. Adsorption of poloxamers and onto 50 nm polystyrene nanoparticles inhibited uptake in the small intestine and reduced uptake from the large intestine, suggesting reduction in adhesion to GALT and other epithelial tissues in the presence of the poloxamer coating but also indirectly suggesting differences in the surface characteristics of lymphoid tissue at different sites in the gut.
We have demonstrated, therefore, both an increase and a decrease in absorption of nanoparticles from the gastro-intestinal tract and some, albeit serendipitous, control of the site of uptake and absorption, which should provide pointers for the future development of systems with optimal uptake characteristics.
Uptake of PMMA nanoparticles from the gastrointestinal tract after oral administration to rats: Modification of the body distribution after suspension in surfactant solutions and in oil vehicles. The animals were sacrificed after 30 min, 1, 2, 4, 8 h, 1, and 4 days, the blood was collected, and different organs and tissues were removed.
The gastrointestinal GI -tract was separated into stomach, small intestine, and colon. The contents of those parts were collected and the remaining GI-tract sections thoroughly rinsed. The radioactivity in the above organs, tissues, and GI-tract contents were determined using a scintillation counter. The radioactivity concentrations were highest in the GI-tract content and decreased rather rapidly between 2 h and 1 day.
These concentration did not correlate totally to those in the GI-tract contents. The highest concentrations in the body were observed between 15 and 60 min but remained at considerable levels for 4 days. No significant difference appeared between saline without surfactants and peanut oil.
Binding and uptake of biodegradable poly-DL-lactide micro- and nanoparticles in intestinal epithelia. The use of biodegradable particles as oral delivery vehicles for macromolecular drugs was investigated. We evaluated the binding, uptake and absorption of poly-dl-lactide PLA micro- and nanoparticles in Caco-2 monolayers and in ileal tissue and gut associated lymphoid tissue GALT of anaesthetised rats and rabbits.
Nanoparticles were found to be absorbed better than microparticles. Overall, little discrimination in uptake patterns was evident between Peyer's patch PP and non-PP tissue while rat ileum showed a greater uptake capacity than rabbit.
Our results show that uptake of PLA particles was low capacity, size-dependent and predominantly transcellular in all systems. The affinity of PLA particles for intestinal epithelia and GALT needs to be greatly enhanced in order to achieve improved oral bioavailability of macromolecules.
Evaluation of nano- and microparticle uptake by the gastrointestinal tract. Numerous papers over the last two decades have demonstrated that particle uptake by the gastrointestinal tract is a reality. In addition, polymeric nano- and microparticles have proved to be useful delivery systems to enhance oral bioavailability of poorly absorbed drugs or to induce mucosal immune response.
However, despite the amount of data available, no set criteria are available for the design of a good particulate carrier for oral delivery of peptides or antigens. This is partly due to the publication of conflicting and confusing data. The source of discrepancy is actually multiparametric e. The purpose of this review is to discuss the advantages and the limitations of the methodologies and the models used to evaluate gastrointestinal uptake of nano- and microparticles.
To study the uptake of biodegradable microparticles in Caco-2 cells. Biodegradable microparticles of polylactic polyglycolic acid co-polymer PLGA The microparticle uptake in Caco-2 cells was studied by confocal microscopy and also by quantitating the 6-coumarin content of the microparticles taken up by the cells. The effects of microparticle concentration, and incubation time and temperature on microparticle cell uptake were also studied.
The study demonstrated that the Caco-2 cell microparticle uptake significantly depends upon the microparticle diameter. Similarly in terms of number the uptake of 0. The efficiency of uptake of 0. The Caco-2 cell microparticle 0. The uptake of microparticles increased with incubation time, reaching a steady state at two hours.
The uptake was greater at an incubation temperature of 37 degrees C compared to at 4 degrees C. The Caco-2 cell microparticle uptake was microparticle diameter, concentration, and incubation time and temperature dependent. The small diameter microparticles 0. The results thus suggest that the mechanism of uptake of microparticles in Caco-2 cell is particle diameter dependent.
Caco-2 cells are used as an in vitro model for gastrointestinal uptake, and therefore the results obtained in these studies could be of significant importance in optimizing the microparticle-based oral drug delivery systems. Gastrointestinal Uptake of Biodegradable Microparticles: Effect of Particle Size. To investigate the effect of microparticle size on gastrointestinal tissue uptake. Biodegradable microparticles of various sizes using polylactic polyglycolic acid The uptake of microparticles was studied in rat in situ intestinal loop model and quantitatively analyzed for efficiency of uptake.
In general, the efficiency of uptake of nm size particles by the intestinal tissue was 15— fold higher compared to larger size microparticles. The efficiency of uptake was dependent on the type of tissue, such as Peyer's patch and non patch as well as on the location of the tissue collected i.
Depending on the size of microparticles, the Peyer's patch tissue had 2— fold higher uptake of particles than the non-patch tissue collected from the same region of the intestine. There is a microparticle size dependent exclusion phenomena in the gastrointestinal mucosal tissue with nm size particles showing significantly greater tissue uptake.
This has important implications in designing of nanoparticle-based oral drug delivery systems, such as an oral vaccine system. Poly diethyl methylidenemalonate Nanoparticles as a Potential Drug Carrier: Polymerization of diethyl methylidenemalonate DEMM, 1a in 0. The weight-average and number-average molecular weight of the resulting polymer were and , respectively. A statistically significant p less than 0. The poly DEMM nanoparticles were not absorbed and were totally cleared from the gastrointestinal tract 24 h after oral dosage.
The very slow bioelimination process observed after iv administration limits the usefulness of poly DEMM nanoparticles as a systemic drug carrier. Nevertheless, their oral administration as bioavailability enhancers can be envisaged.
Moreover, the fact that nanoparticles are readily produced in a medium near neutrality should be emphasized. Emphasis is placed on the relative contributions of quantitative bulk tissue analysis with respect to qualitative and quantitative morphological analysis.
The discussion is extended to observations on factors influencing the particle translocation process including variation in particle uptake in relation to intestinal region and time post-dose administration based on data for uptake of -2 microns latex particles by rat Peyer's patch tissue. Although a significant body of data now identifies the intestinal processus of particle translocation it is underlined that discrepancies may arise as a consequence of different analytical approaches and that this is an issue to be addressed for valid comparisons of data.
Uptake and translocation of microparticles in small intestine: Morphology and quantification of particle distribution. The intestinal transit of large micro- particles to other sites of the body remains a controversial issue of relevance in various fields of study. In this report fluorescent polystyrene latex microparticles in the size range of 2 microns were used as models for nonspecifically absorbed nonbiodegradable particulates.
They were administered to young adult rats as a single oral dose of 1. Quantification of solubilized tissue samples and fluorescence epi- and confocal qualitative and quantitative microscopy showed uptake of latex microparticles in all parts of the intestine sampled, but with the proximal segment the preferential site of absorption. The maximum uptake of particles occurred 0. Translocation of small numbers of particles to the mesenteric lymph nodes was also detected at 0.
Transmucosal passage of particles occurred primarily in the villous tissues adjacent to the Peyer's patch regions. These studies give confirmatory evidence for the uptake and translocation of microparticulates across the mucosal barrier and provide new information regarding site- and time-related effects on particle uptake and the involvement of the villous epithelium in particle translocation.
Preparation and Characterization of Novel Poly methylidene Malonate 2. Average nanoparticle sizes, molecular weights, and biodegradability of this potential drug carrier were determined under various conditions. As previously demonstrated for other similar monomers, i. Ethanol release from the ester-bearing side chains indicated that the polymers were susceptible to hydrolysis when incubated in basic pH or in rat plasma. A secondary degradation pathway, yielding formaldehyde through a reverse Knoevenagel's reaction, was minimal.
Cytotoxicity studies of this new vector, in vitro, against L fibroblast cells demonstrated that PMM 2. Pharmacokinetic studies were also carried out to observe the fate of 14C-labelled PMM 2. The body distribution of the polymer was estimated by measuring the radioactivity associated with liver, spleen, lung and kidneys.
In this study, we demonstrate the role of M cells in uptake of poly D-L-lactic-co-glycolic acid PLGA microspheres and transport into rabbit Peyer's patches. Microspheres 1 to 10 microns in diameter composed of PLGA microspheres visualized as electron-lucent, spherical particles were taken up by M cells by pseudopod-like extensions of the M cell apical membrane and translocated to the pocket region containing mononuclear leukocytes within 60 min.
These results indicate that PLGA microspheres can be directed to M cell apical surfaces for delivery to immunocompetent cells in gut-associated lymphoid tissues. Streptavidin-biotin receptor-ligand interaction forces were measured directly as a function of their intermolecular separation in various salt solutions and at various temperatures with a surface forces apparatus.
At intermediate separations, down to approximately 10 A, the interaction is governed by repulsive steric and attractive van der Waals and hydrophobic forces. A much stronger short-range attraction giving rise to the strong, specific adhesive binding was measured at molecular separations of less than 5 A. A decrease in the pH from 7. This observed behavior can be attributed to the titration of two histidines on the biotin binding surface of streptavidin.
These results reveal a strong sensitivity of the long-range interaction forces to the detailed amino acid composition of the biotin binding surface. They also demonstrate the powerful regulatory potential conferred by small changes in local surface ionic conditions on protein interaction forces over different distance regimes. The effects of temperature on receptor-ligand dynamics and on the strength of intermembrane adhesion forces were studied by measuring the long-range force profiles and short-range adhesion forces above and below the chain melting temperature Tc approximately 30 degrees C of the lipids in the supporting bilayers.
This effect was attributed to the enhanced rates of lateral diffusion and molecular rearrangements on the more fluid bilayer surfaces, which resulted in greater and more rapid intermembrane bond formation. A change in the rates of molecular rearrangements was also found to affect the repulsive part of the interaction potential at intermediate separations A via modulation of the steric repulsion between streptavidin and the highly flexible, polymer-like biotin molecules.
This is expected to have a large effect on the association rates of receptor-ligand binding, even if it does not change the equilibrium binding energy. Entirely biodegradable poly D, L-lactic acid PLA50 nanoparticles coated with albumin were prepared by the solvent evaporation technique.
The degradation of the albumin coating was monitored by HPLC, whereas PLA50 degradation was determined by size exclusion chromatography SEC as well as by the detection of lactate in bulk solution by enzymatic assay. As expected, the coating effect of albumin, a readily digestible protein, rapidly disappeared in both gastric and intestinal media, thus exposing albumin-free PLA50 cores to hydrolytic processes. In pepsin-rich simulated gastric fluid, no degradation of the PLA50 core was observed over 8 h incubation time.
In contrast, in pancreatin-rich simulated intestinal fluid, the PLA50 nanoparticles were rapidly converted into lactate. The results showed that the PLA50 degradation was mainly due to an enzymatic cleavage process. Further experiments showed the involvement of lipases in the degradation of the PLA50 core in simulated intestinal fluid. Nanoparticles and microparticles for drug and vaccine delivery. Nanoparticles are polymeric particles in the nanometer size range whereas microparticles are particles in the micrometre size range.
Both types of particle are used as drug carriers into which drugs or antigens may be incorporated in the form of solid solutions or solid dispersions or onto which these materials may be absorbed or chemically bound. These particles have been shown to enhance the delivery of certain drugs across a number of natural and artificial membranes.
In addition, the particles were shown to accumulate in areas of the intestine that appear to be the Peyer's patches. Possibly because of the combination of both effects these particles were able to significantly improve the bioavailability of some drugs after peroral administration in comparison with solutions.
Recently nanoparticles coated with polysorbate 80 enabled the passage of small peptides and other drugs across the blood-brain barrier and the exhibition of a pharmacological effect after intravenous injection. Without the use of this type of nanoparticles the drugs did not cross this barrier and yielded no effect. Biologically adhesive delivery systems offer important advantages over conventional drug delivery systems.
Here we show that engineered polymer microspheres made of biologically erodable polymers, which display strong adhesive interactions with gastrointestinal mucus and cellular linings, can traverse both the mucosal absorptive epithelium and the follicle-associated epithelium covering the lymphoid tissue of Peyer's patches.
The polymers maintain contact with intestinal epithelium for extended periods of time and actually penetrate it, through and between cells. Thus, once loaded with compounds of pharmacological interest, the microspheres could be developed as delivery systems to transfer biologically active molecules to the circulation. We show that these microspheres increase the absorption of three model substances of widely different molecular size: To investigate the usefulness of a surface-conjugated, bioadhesive molecule, tomato lectin, to augment intestinal uptake of orally administered inert nanoparticles.
Fluorescent nm polystyrene nanoparticles with tomato lectin covalently surface coupled using a carbodiimide reaction were administered to female Wistar rats by oral gavage daily for 5 days. Intestinal uptake of tomato lectin-conjugated nanoparticles via the villous tissue was 15 times higher than uptake by the gut-associated lymphoid tissue. The application of tomato lectin as a bioadhesive agent in vivo has been demonstrated to enhance subsequent intestinal transcytosis of colloidal particulates to which it is bound.
Mucoadhesion of polystyrene nanoparticles having surface hydrophilic polymeric chains in the gastrointestinal tract. The mucoadhesion of polystyrene nanoparticles having surface hydrophilic polymeric chains in the gastrointestinal GI tract was investigated in rats.
Radiolabeled nanoparticles were synthesized by adding hydrophobic 3- trifluoromethyl m-[I]iodophenyl diazirine in the final process of nanoparticle preparation. The radioiodonated diazirine seemed to be incorporated in the hydrophobic polystyrene core of nanoparticles. The diazirine incorporated in nanoparticles exhibited little leakage from them even though they were mixed with a solution corresponding to GI juice. The change in blood ionized calcium concentration after oral administration of salmon calcitonin sCT with nanoparticles showed that the in vivo enhancement of sCT absorption by radiolabeled nanoparticles was the same as that by non-labeled nanoparticles.
The GI transit rates of nanoparticles having surface poly N-isopropylacrylamide , poly vinylamine and poly methacrylic acid chains, which can improve sCT absorption, were slower than that of nanoparticles covered by poly N-vinylacetamide , which does not enhance sCT absorption at all. These slow transit rates were probably the result of mucoadhesion of nanoparticles. The strength of mucoadhesion depended on the structure of the hydrophilic polymeric chains on the nanoparticle surface.
The mucoadhesion of poly N-isopropylacrylamide nanoparticles, which most strongly enhanced sCT absorption, was stronger than that of ionic nanoparticles, and poly N-vinylacetamide nanoparticles probably did not adhere to the GI mucosa. These findings demonstrated that there is a good correlation between mucoadhesion and enhancement of sCT absorption. Adv Drug Deliv Rev It was also argued that the two modes are commonly associated with different kinds of communicative function.
For these various reasons, it was concluded that the different modes necessarily require the use of rather different compositional and comprehension skills. Again, there is certainly some truth in these claims. But in recent times the general validity of this bi-modal view of speech and writing as very distinct language modes has been questioned. Olson briefly mentions some reasons why this is so, and others can be found. Speech can also be recorded, so it need not fade rapidly, and can be replayed for multiple hearings.
Moreover, with the advent of information technology new ways of using language are emerging which make it difficult to continue to argue that the two modes are completely distinct in nature, or in the skills they require for their use. Consider, for example, the use of email, conferencing and other similar kinds of computer-based communication.
We will be looking at those kinds of language use, and at multimodal communication, in section 4. For further information, take a look at our frequently asked questions which may give you the support you need.
Skip to main content. Course content Expand Learning materials Label Time: Intermediate This unit explores the rapidly changing field of l Language and literacy in a changing world Introduction Learning outcomes 1 Talk and the processes of teaching and learning 1. Literacy as cognitive skill 2. Literacy as social practice 2.
There was a problem providing the content you requested
In vitro and in vivo Evaluation of Poly(Methylidene Malonate ) Microparticles Behavior for Oral Administration. Denture status 55 Intervention urgency Section 2: Oral health self- assessment Self-assessment of oral health and risks Oral. Significant oral injury will still occur in spite of preventive activities. Sports during which protective equipment for the head is worn, which may thus.