Página 1 dos resultados de 57 itens digitais encontrados em 0.114 segundos

A poloxamer/chitosan in situ forming gel with prolonged retention time for ocular delivery

GRATIERI, Tais; GELFUSO, Guilherme Martins; ROCHA, Eduardo Melani; SARMENTO, Victor Hugo; FREITAS, Osvaldo de; LOPEZ, Renata Fonseca Vianna
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
85.86%
The aim of the present work was to obtain an ophthalmic delivery system with improved mechanical and mucoadhesive properties that could provide prolonged retention time for the treatment of ocular diseases. For this, an in situ forming gel comprised of the combination of a thermosetting polymer, poly (ethylene oxide)-poly (propylene oxide)-poly (ethylene oxide) (PEO-PPO-PEO, poloxamer), with a mucoadhesive agent (chitosan) was developed. Different polymer ratios were evaluated by oscillatory rheology, texture and mucoadhesive profiles. Scintigraphy studies in humans were conduced to verify the retention time of the formulations developed. The results showed that chitosan improves the mechanical strength and texture properties of poloxamer formulations and also confers mucoadhesive properties in a concentration-dependent manner. After a 10-min instillation of the poloxamer/chitosan 16:1 formulation in human eyes, 50-60% of the gel was still in contact with the cornea surface, which represents a fourfold increased retention in comparison with a conventional solution. Therefore, the developed formulation presented adequate mechanical and sensorial properties and remained in contact with the eye surface for a prolonged time. In conclusion...

Sistemas de liberação ocular contendo fluconazol: obtenção, caracterização e liberação passiva e iontoforética in vitro e in vivo; Ocular delivery systems for fluconazole: obtention, characterization and in vitro/in vivo passive and iontophoretic delivery.

Gratieri, Taís
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 10/06/2010 PT
Relevância na Pesquisa
96.01%
A ceratite fúngica é uma doença grave que pode levar à perda da visão. O tratamento consiste na aplicação de antifúngicos, no entanto a administração tópica não tem se mostrado efetiva devido aos mecanismos de defesa do olho que levam à baixa retenção da formulação no local de aplicação e à baixa permeação do fármaco através da córnea. Sendo assim, formulações mais adequadas e sistemas de liberação vêm sendo estudados na tentativa de melhorar a biodisponibilidade local de antifúngicos. No presente trabalho foram obtidos e caracterizados dois sistemas para a liberação ocular do fluconazol (FLU), um antifúngico de atividade reconhecida: um gel termorreversível in situ e micropartículas poliméricas. A permeação passiva e iontoforética do fármaco através da córnea foi estudada in vitro a partir dos sistemas desenvolvidos. O gel termorreversível in situ contendo 16% de poloxamer e 1,0% de quitosana apresentou temperatura de geleificação adequada, propriedades mucoadesivas, melhores parâmetros mecânicos (dureza, compressibilidade e adesividade) que ambos os polímeros separadamente e mostrou-se superior que micropartículas poliméricas, com fluxo de permeação passiva cerca de duas vezes maior. A maior quantidade de fármaco retido na córnea foi obtida após aplicação da iontoforese em solução aquosa do fármaco. Ainda assim...

Avaliação de formulações de uso tópico a base de insulina no distúrbio das glândulas lacrimais e na regeneração da córnea em ratos diabéticos; Evaluation of topical formulations based insulin disorder of lacrimal glands and in the regeneration of the cornea in diabetic rats

Cruz, Estael Luzia Coelho Madeira da
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 18/07/2014 PT
Relevância na Pesquisa
96.01%
Distúrbios na superfície da córnea e nas glândulas lacrimais acometem com frequência os indivíduos com diabetes mellitus. Atualmente não existe tratamento seguro e eficaz para feridas na córnea e o tratamento da síndrome do olho seco (SOS) é predominantemente sintomático. A administração tópica da insulina (INS) é uma estratégia promissora para tratar esses distúrbios, devido à presença de seus receptores na superfície ocular e na glândula lacrimal, e aos seus efeitos metabólicos e mitogênicos. No entanto, os fármacos aplicados topicamente na forma de solução são rapidamente drenados do olho, resultando em uma baixa biodisponibilidade local. O objetivo deste trabalho foi desenvolver formulações contendo INS e avaliar a sua influência no distúrbio das glândulas lacrimais e na regeneração da córnea em ratos diabéticos. Foram desenvolvidas quatro formulações contendo 1 UI/mL de INS: dispersão contendo insulina (DISP INS), dispersão contendo micropartículas quitosana/INS (DISP MP INS), gel termorreversível in situ com INS (Gel INS) e Gel contendo as micropartículas quitosana/INS (Gel MP INS). Também foram produzidas formulações "brancas", sem a veiculação do fármaco: dispersão contendo micropartículas sem insulina (DISP MP s/INS); gel termorreversível in situ sem insulina (Gel s/INS). As MP incorporadas nas formulações foram preparadas por spray drying e apresentaram tamanho de 4...

Síntese de um precursor catalítico Ni-beta-diimina heterogeneizado a partir do método sol-gel e sua utilização em reações de polimerização de eteno

Souza, Caroline Guterres de
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
45.75%
Este trabalho descreve a utilização do método sol-gel aplicado à produção de precursores catalíticos de níquel-b-diimina suportados em materiais híbridos. Numa primeira etapa foram obtidos materiais híbridos pela incorporação in-situ do ligante diimina N,N-bis(2,6-diisopropilfenil)-2,4-pentanodiimina durante a síntese sol-gel da sílica. Incialmente foram obtidos materiais híbridos contendo o ligante diimina, variando-se as condições experimentais de síntese. As condições variadas foram: quantidade de matéria orgânica adicionada (6 ou 30 mmol), quantidade de TEOS adicionado (45 ou 225 mmol) e tipo de catalisador empregado (HF ou NH4OH). Os materiais híbridos foram caracterizados por Análise Elementar (CHN), Espectroscopia na Região do Infravermelho (IV), Espectroscopia na Região do Ultravioleta-Visível (UV-Vis), Análise Termogravimétrica (TGA), Microscopia Eletrônica de Varredura (MEV) e também foram realizadas as Isotermas de Adsorção e Dessorção de Nitrogênio. Pela Análise Elementar, verificaou-se que a incorporação do ligante diimina ficou entre 19 e 49,5 % nos xerogéis que utilizaram HF como catalisador e entre 6 e 26 % para os que utilizaram NH4OH. A decomposição da matéria orgânica se dá entre 150 e 300 °C...

Cytocompatibility evaluation of amphiphilic, thermally responsive and chemically crosslinkable macromers for in situ forming hydrogels

Klouda, Leda; Hacker, Michael C.; Kretlow, James D.; Mikos, Antonios G.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
65.73%
The cytocompatibility of amphiphilic, thermoresponsive and chemically crosslinkable macromers was examined in vitro. Macromers synthesized from pentaerythritol diacrylate monostearate, N–isopropylacrylamide, acrylamide and hydroxyethyl acrylate in different molar ratios and with varying molecular weights and lower critical solution temperatures were evaluated for cytocompatibility with rat fibroblasts. Cell viabilities of over 60% percent for all and over 80% for most formulations were observed after 24-h incubation with macromers with molecular weights in the range of approximately 1500 to 3000 Da. The chemical modification of the macromers with a (meth)acrylate group was shown to have a time- and dose-dependent effect on cell viability. Uncrosslinked macromers with lower degrees of (meth)acrylation allowed for cell viability of over 60% for up to 6 h. (Meth)acrylated macromers with lower critical solution temperature (LCST) closer to physiological temperature allowed for higher cell viabilities as opposed to those with lower LCST. The data suggest that when the (meth)acrylated macromers are assembled into a physical gel, their cytotoxicity is diminished. After gel phase separation, cytotoxicity increased. This study gives information on the parameters that enable viable cell encapsulation for in situ forming hydrogel systems.

Dual-Drug Delivery System Based on In Situ Gel-Forming Nanosuspension of Forskolin to Enhance Antiglaucoma Efficacy

Gupta, Saurabh; Samanta, Malay K.; Raichur, Ashok M.
Fonte: Springer US Publicador: Springer US
Tipo: Artigo de Revista Científica
Publicado em 25/02/2010 EN
Relevância na Pesquisa
45.77%
The present study was designed to improve the bioavailability of forskolin by the influence of precorneal residence time and dissolution characteristics. Nanosizing is an advanced approach to overcome the issue of poor aqueous solubility of active pharmaceutical ingredients. Forskolin nanocrystals have been successfully manufactured and stabilized by poloxamer 407. These nanocrystals have been characterized in terms of particle size by scanning electron microscopy and dynamic light scattering. By formulating Noveon AA-1 polycarbophil/poloxamer 407 platforms, at specific concentrations, it was possible to obtain a pH and thermoreversible gel with a pHgel/Tgel close to eye pH/temperature. The addition of forskolin nanocrystals did not alter the gelation properties of Noveon AA-1 polycarbophil/poloxamer 407 and nanocrystal properties of forskolin. The formulation was stable over a period of 6 months at room temperature. In vitro release experiments indicated that the optimized platform was able to prolong and control forskolin release for more than 5 h. The in vivo studies on dexamethasone-induced glaucomatous rabbits indicated that the intraocular pressure lowering efficacy for nanosuspension/hydrogel systems was 31% and lasted for 12 h...

In Situ Forming Polymeric Drug Delivery Systems

Madan, M.; Bajaj, A.; Lewis, S.; Udupa, N.; Baig, J. A.
Fonte: Medknow Publications Publicador: Medknow Publications
Tipo: Artigo de Revista Científica
Publicado em //2009 EN
Relevância na Pesquisa
65.85%
In situ forming polymeric formulations are drug delivery systems that are in sol form before administration in the body, but once administered, undergo gelation in situ, to form a gel. The formation of gels depends on factors like temperature modulation, pH change, presence of ions and ultra violet irradiation, from which the drug gets released in a sustained and controlled manner. Various polymers that are used for the formulation of in situ gels include gellan gum, alginic acid, xyloglucan, pectin, chitosan, poly(DL-lactic acid), poly(DL-lactide-co-glycolide) and poly-caprolactone. The choice of solvents like water, dimethylsulphoxide, N-methyl pyrrolidone, triacetin and 2-pyrrolidone for these formulations depends on the solubility of polymer used. Mainly in situ gels are administered by oral, ocular, rectal, vaginal, injectable and intraperitoneal routes. The in situ gel forming polymeric formulations offer several advantages like sustained and prolonged action in comparison to conventional drug delivery systems. The article presents a detailed review of these types of polymeric systems, their evaluation, advancements and their commercial formulations. From a manufacturing point of view, the production of such devices is less complex and thus lowers the investment and manufacturing cost.

Formulation and Evaluation of in situ Gels Containing Clotrimazole for Oral Candidiasis

Harish, N. M.; Prabhu, P.; Charyulu, R. N.; Gulzar, M. A.; Subrahmanyam, E. V. S.
Fonte: Medknow Publications Publicador: Medknow Publications
Tipo: Artigo de Revista Científica
Publicado em //2009 EN
Relevância na Pesquisa
45.77%
Gel dosage forms are successfully used as drug delivery systems to control drug release and protect the medicaments from a hostile environment. The main objective is to formulate and evaluate in situ oral topical gels of clotrimazole based on the concept of pH triggered and ion activated systems. The system utilizes polymers that exhibit sol-to-gel phase transition due to change in specific physico-chemical parameters. A pH triggered system consisting of carbopol 934P (0.2-1.4% w/v) and ion triggered system using gellan gum (0.1-0.75% w/v) along with hydroxylpropylmethylcelluose E50LV was used to prolong the release of clotrimazole (0.1% w/v). Formulations were evaluated for gelling capacity, viscosity, gel strength, bioadhesive force, spreadability, microbiological studies and in vitro release. The use of carbopol as in situ gel forming system was substantiated by the property to transform into stiff gels when the pH was raised, whereas in gellan gum this transformation occurred in the presence of monovalent/divalent cations. Effect of calcium carbonate and other process parameters optimized and found that increase in calcium ions produced stronger gels. The drug content, clarity, and pH of the formulation were found to be satisfactory. The viscosity was found to be in the range 5 to 85 centipoise for the sol...

In Situ Gelling Gelrite/Alginate Formulations as Vehicles for Ophthalmic Drug Delivery

Liu, Yuejiang; Liu, Jinpeng; Zhang, Xiaolin; Zhang, Ruodan; Huang, Yongliang; Wu, Chunjie
Fonte: Springer US Publicador: Springer US
Tipo: Artigo de Revista Científica
Publicado em 31/03/2010 EN
Relevância na Pesquisa
45.72%
The objective of this study was to develop an ion-activated in situ gelling vehicle for ophthalmic delivery of matrine. The rheological properties of polymer solutions, including Gelrite, alginate, and Gelrite/alginate solution, were evaluated. In addition, the effect of formulation characteristics on in vitro release and in vivo precorneal drug kinetic of matrine was investigated. It was found that the optimum concentration of Gelrite solution for the in situ gel-forming delivery systems was 0.3% (w/w) and that for alginate solution was 1.4% (w/w). The mixture of 0.2% Gelrite and 0.6% alginate solutions showed a significant enhancement in gel strength at physiological condition. On the basis of the in vitro results, the Gelrite formulations of matrine-containing alginate released the drug most slowly. For each tested polymer solution, the concentration of matrine in the precorneal area was higher than that of matrine-containing simulated tear fluid (STF) almost at each time point (p < 0.05). The area under the curve of formulation 16 (0.2%Gelrite/0.6%alginate) was 4.65 times greater than that of containing matrine STF. Both the in vitro release and in vivo pharmacological studies indicated that the Gelrite/alginate solution had the better ability to retain drug than the Gelrite or alginate solutions alone. The tested formulation was found to be almost non-irritant in the ocular irritancy test. The overall results of this study revealed that the Gelrite/alginate mixture can be used as an in situ gelling vehicle to enhance ocular retention.

Preparation and Investigation of Sustained Drug Delivery Systems Using an Injectable, Thermosensitive, In Situ Forming Hydrogel Composed of PLGA–PEG–PLGA

Khodaverdi, Elham; Tekie, Farnaz Sadat Mirzazadeh; Mohajeri, Seyed Ahmad; Ganji, Fariba; Zohuri, Gholamhossein; Hadizadeh, Farzin
Fonte: Springer US Publicador: Springer US
Tipo: Artigo de Revista Científica
Publicado em 18/04/2012 EN
Relevância na Pesquisa
55.63%
In situ gelling systems are very attractive for pharmaceutical applications due to their biodegradability and simple manufacturing processes. The synthesis and characterization of thermosensitive poly(d,l-lactic-co-glycolic acid) (PLGA)–polyethylene glycol (PEG)–PLGA triblock copolymers as in situ gelling matrices were investigated in this study as a drug delivery system. Ring-opening polymerization using microwave irradiation was utilized as a novel technique, and the results were compared with those using a conventional method of polymerization. The phase transition temperature and the critical micelle concentration (CMC) of the copolymer solutions were determined by differential scanning calorimetry and spectrophotometry, respectively. The size of the micelles was determined with a light scattering method. In vitro drug release studies were carried out using naltrexone hydrochloride and vitamin B12 as model drugs. The rate and yield of the copolymerization process via microwave irradiation were higher than those of the conventional method. The copolymer structure and concentration played critical roles in controlling the sol–gel transition temperature, the CMC, and the size of the nanomicelles in the copolymer solutions. The rate of drug release could be modulated by the molecular weight of the drugs...

Injectable PAMAM dendrimer-PEG hydrogels for the treatment of genital infections: formulation, in-vitro and in-vivo evaluation

Navath, Raghavendra S.; Menjoge, Anupa R.; Dai, Hui; Romero, Roberto; Kannan, Sujatha; Kannan, Rangaramanujam M.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
45.82%
Local intravaginal drug therapy is preferred for treatment of ascending genital infections during pregnancy. In the present study, in-situ forming biodegradable hydrogel for sustained release of amoxicillin in the cervicovaginal region is described. A generation 4 poly(amidoamine) [G4-(NH2)64] dendrimer with peripheral thiopyridyl terminations is crosslinked with 8-arm polyethylene glycol (PEG) bearing thiol terminations. The hydrogels were formulated and tested in-vivo in pregnant guinea pig model for volume, retention times, biodegradation, tolerability and transport across fetal membrane. The physicochemical characterization of the hydrogels was carried out using differential calorimetry, SEM, and confocal imaging. The hydrogels offer antibacterial activity arising from sustained release of amoxicillin from gels. The in-vivo studies in guinea pig showed that 100-200 μL of gel sufficiently covered the cervicovaginal region with a residence time of at least 72 h and gel was primarily retained in the maternal tissues without crossing the fetal membranes into the fetus. The dendrimer gels were stable upto 72 h and the in-vivo biodegradation of gel occurred after 72 h and this correlated well with the in-vitro degradation pattern. The pH of the vagina was not altered upon application of the gel and none of the animals aborted upto 72 h after application of gel. The histological evaluation of the cervical tissues showed absence of edema in epithelial cell layer...

Nanoparticles laden in situ gelling system for ocular drug targeting

Kumar, Divya; Jain, Nidhi; Gulati, Neha; Nagaich, Upendra
Fonte: Medknow Publications & Media Pvt Ltd Publicador: Medknow Publications & Media Pvt Ltd
Tipo: Artigo de Revista Científica
Publicado em //2013 EN
Relevância na Pesquisa
55.85%
Designing an ophthalmic drug delivery system is one of the most difficult challenges for the researchers. The anatomy and physiology of eye create barriers like blinking which leads to the poor retention time and penetration of drug moiety. Some conventional ocular drug delivery systems show shortcomings such as enhanced pre-corneal elimination, high variability in efficiency, and blurred vision. To overcome these problems, several novel drug delivery systems such as liposomes, nanoparticles, hydrogels, and in situ gels have been developed. In situ-forming hydrogels are liquid upon instillation and undergo phase transition in the ocular cul-de-sac to form viscoelastic gel and this provides a response to environmental changes. In the past few years, an impressive number of novel temperature, pH, and ion-induced in situ-forming systems have been reported for sustain ophthalmic drug delivery. Each system has its own advantages and drawbacks. Thus, a combination of two drug delivery systems, i.e., nanoparticles and in situ gel, has been developed which is known as nanoparticle laden in situ gel. This review describes every aspects of this novel formulation, which present the readers an exhaustive detail and might contribute to research and development.

Development of an enhanced formulation for delivering sustained release of buprenorphine hydrochloride

Koocheki, S.; Madaeni, S.S.; Niroomandi, P.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
45.67%
To control the minimum effective dose, and reduce the number and quantity of administered potent drugs are unique features of advanced drug delivery in situ forming gel formulation. The efficacy, consistency, and increasing the application of existing injection therapies can be enhanced through optimization of controlled released systems by using FDA approved biodegradable PLGA (poly-d,l-lactide-co-glycolide) polymer. The purpose of this study was to develop different in situ forming implant (ISFI) formulations of buprenorphine hydrochloride for post treatment of drug addicts, acute and chronic pains.

Rapidly In Situ Forming Platelet-Rich Plasma Gel Enhances Angiogenic Responses and Augments Early Wound Healing after Open Abdomen

Zhou, Bo; Ren, Jianan; Ding, Chao; Wu, Yin; Hu, Dong; Gu, Guosheng; Li, Jieshou
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
65.77%
Objective. The purposes of our present study were to evaluate the potential of platelet-rich plasma gel to enhance granulation tissue formation after open abdomen and to examine whether the effect was attributable to stimulating rapid neovascularization. Methods. Twenty-four rats underwent colon ascendens stent peritonitis surgery to induce sepsis, followed by intraperitoneal injection of nitrogen to create intra-abdominal hypertension. Four hours later, laparotomies were performed. The rats were randomized into three groups (n = 8 for each group): control, platelet-poor plasma (PPP), and platelet-rich plasma (PRP) groups. One week after the treatment, granulation tissue formation and angiogenesis were evaluated by histological and laser Doppler analysis. Results. The resultant platelet count in platelet-rich plasma was higher than that of PPP. The concentrations of platelet-derived growth factor BB, transforming growth factor β-1, and vascular endothelial growth factor in PRP were significantly higher when compared with that of PPP. Myofibroblast count, granulation tissue thickness, vessel numbers, and blood perfusion were increased in PRP group, followed by PPP group, with control being the least. Conclusion. Rapidly in situ forming platelet-rich plasma gel promoted remarkable neovascularization and early wound healing after open abdomen and may lead to novel and effective treatments for open abdominal wounds.

In Situ Gelation for Cell Immobilization and Culture in Alginate Foam Scaffolds

Andersen, Therese; Markussen, Christine; Dornish, Michael; Heier-Baardson, Helene; Melvik, Jan Egil; Alsberg, Eben; Christensen, Bjørn E.
Fonte: Mary Ann Liebert, Inc. Publicador: Mary Ann Liebert, Inc.
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
45.76%
Essential cellular functions are often lost under culture in traditional two-dimensional (2D) systems. Therefore, biologically more realistic three-dimensional (3D) cell culture systems are needed that provide mechanical and biochemical cues which may otherwise be unavailable in 2D. For the present study, an alginate-based hydrogel system was used in which cells in an alginate solution were seeded onto dried alginate foams. A uniform distribution of NIH:3T3 and NHIK 3025 cells entrapped within the foam was achieved by in situ gelation induced by calcium ions integrated in the foam. The seeding efficiency of the cells was about 100% for cells added in a seeding solution containing 0.1–1.0% alginate compared with 18% when seeded without alginate. The NHIK 3025 cells were allowed to proliferate and form multi-cellular structures inside the transparent gel that were later vital stained and evaluated by confocal microcopy. Gels were de-gelled at different time points to isolate the multi-cellular structures and to determine the spheroid growth rate. It was also demonstrated that the mechanical properties of the gel could largely be varied through selection of type and concentration of the applied alginate and by immersing the already gelled disks in solutions providing additional gel-forming ions. Cells can efficiently be incorporated into the gel...

A Novel In Situ Gel Formulation of Ranitidine for Oral Sustained Delivery

Xu, Haoping; Shi, Min; liu, Ying; Jiang, Jinling; Ma, Tao
Fonte: The Korean Society of Applied Pharmacology Publicador: The Korean Society of Applied Pharmacology
Tipo: Artigo de Revista Científica
Publicado em /03/2014 EN
Relevância na Pesquisa
45.81%
The main purpose of this study was to develop a novel, in situ gel system for sustained delivery of ranitidine hydrochloride. Ranitidine in situ gels at 0.2%, 0.5%, and 1.0% gellan gum concentration (w/v) were prepared, respectively, and characterized in terms of preparation, viscosity and in vitro release. The viscosity of the gellan gum formulations in solution increased with increasing concentrations of gellan gum. In vitro study showed that the release of ranitidine from these gels was characterized by an initial phase of high release (burst effect) and translated to the second phase of moderate release. Single photon emission computing tomography technique was used to evaluate the stomach residence time of gel containing 99mTc tracer. The animal experiment suggested in situ gel had feasibility of forming gels in stomach and sustained the ranitidine release from the gels over the period of at least 8 h. In conclusion, the in situ gel system is a promising approach for the oral delivery of ranitidine for the therapeutic effects improvement.

Preparation of SLN-containing Thermoresponsive In-situ Forming Gel as a Controlled Nanoparticle Delivery System and Investigating its Rheological, Thermal and Erosion Behavior

Dorraj, Golnar; Moghimi, Hamid Reza
Fonte: Shaheed Beheshti University of Medical Sciences Publicador: Shaheed Beheshti University of Medical Sciences
Tipo: Artigo de Revista Científica
Publicado em //2015 EN
Relevância na Pesquisa
85.73%
Various nanoparticles have been investigated as novel drug delivery systems, including solid lipid nanoparticles (SLNs). Due to their rapid clearance from systemic circulation, nanoparticles do not provide sustained action in most cases. Different strategies have been employed to overcome this problem. In this direction, the present study introduces erodible in-situ forming gel systems as potential vehicles for prolonged release of SLNs.

In Situ forming poly(ethylene glycol)-based hydrogels via thiol-maleimide Michael-type addition

Fu, Yao; Kao, Weiyuan John
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
55.77%
The incorporation of cells and sensitive compounds can be better facilitated without the presence of UV or other energy sources that are common in the formation of biomedical hydrogels such as poly(ethylene glycol) hydrogels. The formation of hydrogels by the step-growth polymerization of maleimide- and thiol-terminated poly(ethylene glycol) macromers via Michael-type addition is described. The effects of macromer concentration, pH, temperature, and the presence of biomolecule gelatin on gel formation were investigated. Reaction kinetics between maleimide and thiol functional groups were found to be rapid. Molecular weight increase over time was characterized via gel permeation chromatography during step-growth polymerization. Swelling and degradation results showed incorporating gelatin enhanced swelling and accelerated degradation. Increasing gelatin content resulted in the decreased storage modulus (G’). The in vitro release kinetics of FITC-labeled dextran from the resulting matrices demonstrated the potential in the development of novel in situ gel-forming drug delivery systems. Moreover, the resulting networks were minimally adhesive to primary human monocytes, fibroblasts and keratinocytes thus providing an ideal platform for further biofunctionalizations to direct specific biological response.

The efficacy of topical agents in the treatment of bacterial biofilms: an in vivo sheep study and an in vitro study.

Le, Tong Ba
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2010
Relevância na Pesquisa
55.81%
Introduction: Recent evidence has demonstrated the presence of bacterial biofilms on the mucosa of patients with Chronic Rhinosinusitis (CRS), suggesting their role in the pathogenesis of the condition. This thesis contains two separate studies. The studies investigated novel topical therapies by using previously established in vitro and in vivo biofilm growth and detection methods. In the first study, several different proposed anti-biofilm agents were evaluated in a sheep biofilm model, each with varying degrees of immediate and short-term success against Staphylococcus aureus biofilms. A second study was conducted to determine the in vitro anti-bacterial and anti-biofilm properties of Chitosan/Dextran (CD) gel, a novel chitosan-based product with remarkable mucosal healing and haemostatic properties. Methods: Three alternative anti-biofilm treatments: Mupirocin, CAZS (Citric Acid Zwitterionic Acid) and Gallium Nitrate were evaluated in a prospective randomized controlled single-blinded trial using a previously established sheep biofilm model of CRS. The sheep mucosal samples were analyzed for presence of S. aureus biofilms using BacLight staining and CLSM, and the degree of biofilm involvement was determined using FISH (Fluorescence In-Situ Hybridization). The MIC/MBC values for CD gel and its constituents were determined by macro-dilution methods described by Jorgensen et al.[1]. Established in vitro biofilms grown from common CRS pathogens (ATCC strains and clinical isolates) were subjected to treatment by CD gel and its components (chitosan and dextran). A 96-well micro-titre crystal-violet staining method described by O’Toole and Kolter [2] was used to determine the anti-biofilm profile of CD gel against several bacterial strains with known biofilm-forming capacity. Results: Following 8 days of inoculation with S. aureus...

Localization of Herpes Simplex Virus Type 1 DNA in Latently Infected BALB/c Mice Neurons Using in situ Polymerase Chain Reaction

Khansarinejad, Behzad; Soleimanjahi, Hoorieh; Ghaemi, Amir; Tiraihi, Taki; Pour Beiranvand, Shahram
Fonte: Pasteur Institute of Iran Publicador: Pasteur Institute of Iran
Tipo: Artigo de Revista Científica
Publicado em /07/2010 EN
Relevância na Pesquisa
45.68%
Background: Herpes simplex virus type-1 (HSV-1) establishes a lifelong latent infection in neurons following primary infection. The existence of latent HSV-1 DNA in the trigeminal ganglia of infected BALB/c mice was examined using a direct in situ PCR technique, based on Digoxigenin-11-dUTP detection system with anti-digoxigenin-peroxidase and 3,3'-diaminobenzidine (DAB) substrate. Methods: Eight-week-old male BALB/c mice were inoculated via the eye by 104 plaque forming unit of wild type Iranian isolates of HSV-1. After establishment of latency, trigeminal ganglia were removed and examined using in situ PCR to detect HSV-1 genome. Finally, the results of in situ PCR were verified by a two-round PCR method, using amplification cocktail of in situ reaction, as a template for a conventional gel base PCR. Results and Conclusion: The results suggest that a direct in situ PCR method using a peroxidase and DAB detection system is a useful means for detection of latent HSV-1 DNA in the latently infected ganglia.