Persistência de palhada e liberação de nutrientes do nabo forrageiro no plantio direto

A palhada das plantas de cobertura, mantida sobre o solo no plantio direto, representa uma reserva de nutrientes para cultivos subseqüentes. O objetivo deste trabalho foi avaliar a decomposição e a liberação de macronutrientes de resíduos de nabo forrageiro. O experimento foi realizado no campo, durante o ano de 1998, no Município de Marechal Cândido Rondon, PR. O nabo forrageiro foi dessecado e manejado com rolo-faca 30 dias após a emergência. Avaliaram-se a persistência de palhada e a liberação de nutrientes dos resíduos aos 0, 13, 35 e 53 dias após o manejo. O delineamento experimental foi de blocos casualizados, com quatro repetições. O nabo forrageiro produziu, até o estádio de pré-florescimento, elevada quantidade de massa seca da parte aérea em cultivo de inverno (2.938 kg ha-1), acumulando 57,2, 15,3, 85,7, 37,4, 12,5 e 14,0 kg ha-1, respectivamente, de N, P, K, Ca, Mg e S. O manejo do nabo forrageiro no estádio de pré-florescimento apresenta rápida degradação da palhada, acarretando liberação de quantidades significativas de macronutrientes. Os nutrientes disponibilizados em maior quantidade e velocidade para a cultura subseqüente, são o K e o N. A maior velocidade de liberação de macronutrientes pelo nabo forrageiro ocorre no período compreendido entre 10 e 20 dias após o manejo da fitomassa.

Liberação intraocular de ofloxacina associada a lente de contato biossintética em ceratite bacteriana experimental em cães

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Utilização de gonadotrofina coriônica humana e cipionato de estradiol associado ao dispositivo de liberação controlada de drogas para sincronização de ovulação em cabras da raça Saanen

Dezesseis cabras nulíparas da raça Saanen foram distribuídas em dois grupos de tratamentos (T1 e T2) para sincronização da ovulação. Inicialmente, ambos os tratamento consistiram na aplicação concomitante do dispositivo de liberação controlada de drogas (CIDR-G®), de 5mg de dinoprost e de 1mg de cipionato de estradiol (CE) (dia 0). No quarto dia aplicaram-se 250UI de eCG e no quinto dia retirou-se o CIDR-G®. As cabras do T1 (n=8) receberam 1mg de CE 24 horas depois da retirada do CIDR-G® e as do T2 (n=8) receberam 250UI de hCG 30 horas após. Sete cabras do T1 e oito do T2 entraram em estro depois da retirada do CIDR-G®. Cabras que receberam hCG permaneceram em estro por 42,0± 6,9 horas e as que receberam CE por 45,0± 5,5 horas (P>0,05). As características ovulatórias não foram influenciadas pelos tratamentos. O intervalo da retirada do CIDR-G® à ovulação para ambos os protocolos de sincronização da ovulação não diferiu (P>0,05) entre tratamentos. As ovulações promovidas pelo CE ocorreram em menor intervalo de tempo.

Estudo in vivo de um sistema de liberação de drogas constituído por hidroxiapatita e cisplatina

Um sistema de liberação constituído por hidroxiapatita e cisplatina foi testado em ratos para avaliação da liberação local e sistêmica do antineoplásico cisplatina. Os animais que receberam os implantes com a droga desenvolveram efeitos colaterais ao tratamento, sendo os mais comuns: anorexia, diarréia, epistaxe e necrose cutânea no sítio de implantação; cerca de 45% deste animais morreram, indicando intoxicação. Amostras de sangue e dos tecidos hepático, renal e muscular de todos os animais pertencentes ao experimento foram submetidas à detecção das concentrações de cisplatina, revelando a cinética de liberação da droga pelo sistema proposto.

Persistência e liberação de macronutrientes e silício da fitomassa de crotalária em função da fragmentação

The persistence of straw, as well as the dynamics of nutrients release of it, are important aspects to consider in the choice of plants for composition of crop rotations in a no tillage system. Thus, the objective of this work was to evaluate the decomposition rate and macronutrients and silicon (Si) release from sunn hemp (Crotalaria juncea L.) phytomass, as a function of management, with and without fragmentation. A randomized blocks design, with four replications, in a factorial 2x6, constituted by two aboveground phytomass management after 75 days after emergence (with and without mechanical fragmentation) and six sampling times (0, 18, 32, 46, 74 and 91 days after management (DAM)), were evaluated the decomposition rate and nutrient release from sunn hemp biomass. The mechanical fragmentation of sunn hemp straw did not change the decomposition and macronutrients release. The maximum release rates occurred 0-18 DAM. Potassium is the most rapidly available nutrient, while the silicon is more slowly released to the ground. Over time there has been increasing Si content in the straw.

Sistemas para liberação colônica: Uma alternativa para a veiculação de fármacos para efeito local ou sistêmico

Problems related to the systemic administration of drugs, such as biodistribution, difficulty of targeting, necessity of high doses to achieve adequate levels of the drug in specific sites, toxicity, and undesirable side effects have lead to the development of systems able to direct the drug to specific sites in the body. Among the possible organs to the targeting of drugs, the colon can be used for local and systemic therapies. By developing such systems some models have been tested, using pH dependent release, release controlled by enzymatic degradation, time controlled release systems and pressure controlled release systems. This review presents an overview of the colonic release of drugs and the strategies used to achieve such targeting.

Liberação de óxido nítrico e tnf-α em macrófagos peritoneais na presença de Melampodium divaricatum (Asteraceae)

The immune responses are mediated by a variety cells and molecules that cells secreted. Macrophages are the first cells that participate in the immune response, and, when are activated, release more than hundred compounds at the extracelular medium, such as cytokine (TNF-α) and the intermediate compounds of the nitrogen (NO). In this paper the release of nitric oxide (NO) and necrose tumoral factor (TNF-α) were determined in peritoneal macrophage cultures of mice in the presence of the 70% ethanolic extract obtained from the flowers of the Melampodium divaricatum (Asteraceae) in the concentrations of 20, 10 and 5 mg/mL. The 70% ethanolic extracts from flowers of the Melampodium divaricatum presented higher liberation of NO and TNF-α in the concentration of the 20 mg/mL when compared with LPS. We conclude that this extract is a potente stimulator of macrophage, could be immunomodulatory activity.

Encapsulação da rifampicina em matrizes poliméricas flutuantes obtidas por liofilização a partir de metilcelulose e ftalato de hidroxipropilmetilcelulose. Avaliação da liberação in vitro

Floating multiparticles for oral administration with different compositions were studied from a matricial polymeric system to obtain sustained release. The polymers used in the multiparticles constitution were methylceullose (MC) and hydroxypropylmethylcelullose phthalate (HPMCP) in several proportions. Spherical and isolated structures were obtained using HPMCP/MC in the range from 1:3 to 1: 13. The diameters of the floating multiparticles were in the range from 3 to 3.25 mm, while the non-floating particles were between 1.75 and 2.1 mm. The morphological analysis by confocal microscopy showed that the probable mechanism of drug release was the diffusion from the inner of particles to external media. The encapsulation of hydrophilic model substances (tartrazin and bordeaux S), showed that the maximum incorporation was about 38%, while for the lipophilic model substances (rifampicin) was 45%. The in vitro release of rifampicin in acid medium was dependent on the ratio HPMCP/MC. In alkaline medium the release followed a two-step profile, with slow release in the initial times and subsequent increase in the higher times The initial drug delivery profile was not dependent on the MC/HPMCP ratio and can be related with the release of the antibiotic from multiparticle inner caused by the swelling of polymers by the presence of water in the system. However, afterwards the release proceeds with typical profile of process involving hydrogels systems.

Polissacarídeos biodegradáveis úteis para a preparação de sistemas de liberação controlada de fármacos. Parte 1: Quitosana

Due to an increasing interest, a vast number of biodegradable polymers have been obtained recently. Polymers naturally produced, such as cellulose, starch, chitosan and alginate, represent biodegradable materials, with low toxicity and low cost. Among polysaccharides, chitosan has been of great interest of the industrial and academic research, due to its special qualities of biodegradability and biocompatibility and, on the other hand, to the versatility of its use in several physical forms and products. A significant growth in the development of new dosage forms capable to deliver the drug in a controlled and targeted way has been observed in these last years. Such pharmaceutical forms search, mainly, the reduction of the dose administered and of the administration frequency, the reduction of adverse side effects and, consequently, a better patient compliance. The present paper describes the use of chitosan in pharmaceutical products, especially in drug controlled delivery systems.

Liberação de mitomicina C - Influência de diferentes materiais

Purpose: To evaluate the quantity of Mitomycin C discharged from different materials with the same size, potentially used in the application of this medicine accessible in the surgery center of an Universitarian Hospital. Material and Method: It was studied 20 fragments with 5 to 5mm, from each 5 materials: Lyostypt, Weck sponge, absorbable cloth which is used to clean, cotton plate and of cotton swab concerning the saturation capacity and the quantity of mitomicyn discharged. In the first stage, it was studied the saturation capacity from each material. In the second stage, it was applied 0,1 ml solution of Mitomicyn C (0,5 mg/ml) and it was measured the biggest discharge halo in the filter paper and the discharged quantity (the difference between the weight before and after the medicine discharge). Results: The absorveble capacity from each material varied from 0,144 ml (absorbable cloth) to 0,216 ml Weck sponge. The discharge of Mitomicyn C was varied too, the biggest was the cotton plate and absorbable cloth. The Weck sponge and the cotton (of cotton swab) discharges the same quantity. Conclusion: The different materials discharged different quantities of Mitomicyn C. This can explain the different results of the trabeculectomy with Mitomicyn C. The surveys must inform not only the material used to apply the mitomycin C but the volume used too. Because the same values of mitomycin C liberation, cotton may substitute Weck sponje in trabeculectomy.

Microemulsões: Estrutura e aplicações como sistema de liberação de fármacos

Depending on formula composition, microemulsions may be used as a vehicle for drug administration. In this work the main applicable parameters used in the development of pharmaceutical microemulsions (ME) are analyzed. The conceptual description of the system, theoretical parameters related to formation of internal phases and some aspects of ME stability are described. The pseudo ternary phase diagram is used to characterize ME boundaries and to describe different structures in several regions of the diagram. Some applications of ME as drug delivery systems for different administration routes are also analyzed. ME offer advantages as drug delivery systems, because they favor drug absorption, being in most cases faster and more efficient than other methods in delivering the same amount of drug.

Citotoxicidade de Styrax camporum Pohl em macrófagos peritoneais e a liberação de H2O2

The immunological response includes wide contexts involving several cells, and the macrophage is crucial in the cellular immune response. Several stimuli to macrophage membrane may induce the liberation of H2O2, contributing to antibacterial and cytotoxicical actions. Nowadays, there is a tendency to study natural products to verify their capacity of acting in the immune system. This study evaluated the citotoxicity of the bulk extract and the hexanic and acetic fractions extracted from Styrax camporum Pohl (Styracaceae) and the production of H2O2, on murine peritonal macrophages cultures exposed to fractions extracted from this plant. The results showed that the fraction HX 2 mg/ml produced the liberation of H 2O2 in high concentrations and to 4 mg/ml was observed high citotoxicity. The fractions AC did not produce the liberation of H 2O2 and EB was produced in low levels. We conclude that this HX is a potent stimulator of macrophage.

Estudos sobre liberação controlada e vetorização de drogas através de lipossomas

The text highlights the state of research related with the application of liposomes in the control of drug delivery and drug target to infectious diseases. Liposomes have several pharmaceutical applications and this manuscript is primarily focused on the potential of this colloidal system as an antibiotic carrier system and of administration through several accesses via to organism. Numerous case studies in which liposomes have successfully been used to improve pharmacological drug effect are presented. Mechanisms involved in drug delivery, application possibilities, research and development and efforts to reach these objectives are discussed. © Copyright Moreira Jr. Editora. Todos os direitos reservados.

Estratégias biotecnológicas para a liberação controlada de antígenos e adjuvantes em vacinas através de lipossomas

Liposomes (LP) are colloidal systems with ability to compartmentalize therapeutic molecules in order to improve biological activity, decreases the potential toxicity, and to obtain prolonged effect. In this work it was discussed the role of the various liposomes types to encapsulate drug molecules able to provoke some immunological response (drugs, antigens and DNA). The effect of the liposomes and the parameters about the formation of the structures are also analyzed. Detailed literature review shows that, depending on the molecules polarity and the superficial charge of the liposome structures, the system may be efficiently used to optimize the therapeutic effects by means of the release control or through a drug delivery mechanism.

Avaliação da liberação de lh e da concentração de progesterona em protocolos ovsynch e heatsynch em bubalinos (bubalus bubalis)

The objective of this study was to evaluate the LH surge after last hormonal injection of synchronization of ovulation protocols in buffalo. Fifteen multiparous buffaloes received 25 mg of Lecirelin in Day 0, and 150 mg of D-Cloprostenol on Day 7. On Day 8, estradiol benzoate was injected in Group 1 (0.5 mg, n = 5) and Group 2 (1.0 mg, n = 5). On Day 9, five buffaloes received 25 mg of Lecirelin (Control). Blood samples were collected for measure the LH concentrations on Day 7 and then every 3 hours until 72 hours after the PGF 2a injection. For evaluation of LH surge were compared the interval between PGF 2a injection to LH surge, duration, amplitude and area under the LH peak. The LH surge occurred 51.0 + 0.0 hours, 47.3 + 2.7 hours and 47.0 + 3.8 hours after PGF 2a injection for Control, Group 1 and Group 2, respectively (P > 0.05). The duration of LH peak in Control (7.8 + 1.5 hours) was shorter than Groups 1 and 2 (10.5 + 1.5 hours vs. 10.8 + 2.4 hours, respectively; P < 0.05). The amplitudes of LH peak were 4.5 + 0.4 ng/mL, 4.0 + 0.4 ng/mL and 4.3 + 0.8 ng/mL for Control, Group 1 and Group 2, respectively (P > 0.05). The area under LH peak for Control (4.8 ± 0.7) was smaller than the areas of the Groups 1 and 2 (8.8 ± 2.5 vs. 8.7 2.2, respectively; P < 0.05). In summary, the estradiol benzoate injection provided higher duration and area of LH peak than GnRH injection in Ovsynch protocol in buffalo.