Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 17 de 17
Filtrar
Mais filtros










Tipo de estudo
Intervalo de ano de publicação
2.
Biomed Res Int ; 2016: 3278359, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27747227

RESUMO

Necrotic enteritis (NE) is an important concern in poultry industry since it causes economic losses, increased mortality, reduction of bird welfare, and contamination of chicken products for human consumption. For decades, the use of in-feed antimicrobial growth promoters (AGPs) has been the main strategy to control intestinal pathogens including Clostridium perfringens (CP), the causative agent of NE. However, the use of AGPs in animal diet has been linked to the emergence and transmission of antimicrobial resistance through food-borne microorganisms, which has led to the ban of AGPs in many countries. This scenario has challenged the poultry industry to search for safer alternative products in order to prevent NE. In this context, the utilization of natural plant extracts with antimicrobial properties appears as a promising and feasible tool to control NE in chicken. In this paper, we review the scientific studies analyzing the potential of plant extracts as alternative feed additives to reduce NE in poultry, with focus on two types of plant products that arise as promising candidates: tannins and essential oils. Some of these products showed antimicrobial activity against CP and coccidia in vitro and in vivo and are able to increase productive performance, emulating the bioactive properties of AGPs.


Assuntos
Anti-Infecciosos/uso terapêutico , Infecções por Clostridium/veterinária , Enterite/tratamento farmacológico , Necrose/tratamento farmacológico , Óleos Voláteis/química , Extratos Vegetais/química , Doenças das Aves Domésticas/tratamento farmacológico , Taninos/química , Animais , Antibacterianos/uso terapêutico , Anti-Infecciosos/química , Infecções por Clostridium/tratamento farmacológico , Clostridium perfringens/efeitos dos fármacos , Farmacorresistência Bacteriana , Tolerância a Medicamentos , Microbiologia de Alimentos , Testes de Sensibilidade Microbiana , Aves Domésticas
3.
Anaerobe ; 34: 139-45, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26037239

RESUMO

Tannins added in the diet are being used to improve nutrition and health in farm animals as an alternative to antibiotic growth promoters and to control enteric clostridial diseases. However, the capacity of Clostridium perfringens to develop resistance under the selective pressure of tannins is unknown. The purpose of this study was to determine if C. perfringens possess the ability to develop resistance against tannins in comparison with antimicrobial agents. Susceptibility for 7 AGPs (antimicrobial growth promoters), 9 therapeutic antimicrobials and 2 tannin based extracts was determined for 30 C. perfringens strains isolated from poultry and cattle. Two susceptible strains were selected and cultured in presence of sub-inhibitory concentrations of tannins and AGPs for resistant sub-populations selection. Tannin resistance of C. perfringens isolates from both animal species revealed no statistically significant differences in MICs (minimum inhibitory concentration). Poultry isolates showed higher MICs to several AGPs compared with cattle isolates. All isolates were susceptible to the therapeutic antimicrobials tested, but avian isolates showed a significantly lower susceptibility to these antimicrobials which was highly correlated with an increased resistance to bacitracin and others AGPs. In-vitro selection of resistant clones suggests that C. perfringens was unable to develop resistance against tannins at least compared to AGPs like bacitracin and avilamycin. Avian origin strains, which were previously exposed to antibiotics showed higher resistance, compared to cattle origin strains. These results suggest that the evolution of resistance against tannins in C. perfringens would be more difficult and slower than to the determined AGPs.


Assuntos
Anti-Infecciosos/metabolismo , Clostridium perfringens/efeitos dos fármacos , Tolerância a Medicamentos , Proantocianidinas/metabolismo , Animais , Bovinos , Clostridium perfringens/isolamento & purificação , Hidrólise , Testes de Sensibilidade Microbiana , Mutação , Taxa de Mutação , Aves Domésticas , Seleção Genética , Inoculações Seriadas
4.
Bioelectrochemistry ; 103: 60-4, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25220563

RESUMO

This work describes the utilization of Pulsed Electric Fields to control the protozoan contamination of a microalgae culture, in an industrial 2.7 m(3) microalgae photobioreactor. The contaminated culture was treated with Pulsed Electric Fields, PEF, for 6h with an average of 900 V/cm, 65 µs pulses of 50 Hz. Working with recirculation, all the culture was uniformly exposed to the PEF throughout the assay. The development of the microalgae and protozoan populations was followed and the results showed that PEF is effective on the selective elimination of protozoa from microalgae cultures, inflicting on the protozoa growth halt, death or cell rupture, without affecting microalgae productivity. Specifically, the results show a reduction of the active protozoan population of 87% after 6h treatment and 100% after few days of normal cultivation regime. At the same time, microalgae growth rate remained unaffected.


Assuntos
Biotecnologia/métodos , Técnicas Eletroquímicas/métodos , Microalgas/crescimento & desenvolvimento , Microalgas/parasitologia , Biotecnologia/instrumentação , Membrana Celular , Desenho de Equipamento , Fotobiorreatores
5.
Anaerobe ; 20: 1-4, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23354004

RESUMO

Clostridium perfringens type E is considered a rare toxinotype and an infrequent cause of enterotoxemia of lambs, calves, and rabbits. Until now, only cases of young animal of C. perfringens type E bovine enterotoxemia, characterized by hemorrhagic enteritis and sudden death, have been reported. The present report details the genotypic characterization of C. perfringens type E isolates obtained from intestinal samples of adult cattle during an outbreak of enterotoxemia in Argentina. The sequences of several housekeeping genes of these isolates were analyzed and compared with those obtained from calves in North America showing a clonal unique lineage.


Assuntos
Doenças dos Bovinos/epidemiologia , Infecções por Clostridium/veterinária , Clostridium perfringens/genética , Clostridium perfringens/isolamento & purificação , Morte Súbita/veterinária , Surtos de Doenças/veterinária , Enterotoxemia/epidemiologia , Animais , Argentina/epidemiologia , Proteínas de Bactérias/genética , Bovinos , Doenças dos Bovinos/microbiologia , Infecções por Clostridium/epidemiologia , Infecções por Clostridium/microbiologia , Clostridium perfringens/classificação , Clostridium perfringens/patogenicidade , Morte Súbita/epidemiologia , Morte Súbita/etiologia , Enterotoxemia/microbiologia , Genótipo , Dados de Sequência Molecular , Tipagem de Sequências Multilocus/métodos , Reação em Cadeia da Polimerase , Análise de Sequência de DNA , Síndrome , Fatores de Virulência/genética
6.
Rev Sci Instrum ; 81(7): 074703, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-20687749

RESUMO

A new circuit topology is proposed to replace the actual pulse transformer and thyratron based resonant modulator that supplies the 60 kV target potential for the ion acceleration of the On-Line Isotope Mass Separator accelerator, the stability of which is critical for the mass resolution downstream separator, at the European Organization for Nuclear Research. The improved modulator uses two solid-state switches working together, each one based on the Marx generator concept, operating as series and parallel switches, reducing the stress on the series stacked semiconductors, and also as auxiliary pulse generator in order to fulfill the target requirements. Preliminary results of a 10 kV prototype, using 1200 V insulated gate bipolar transistors and capacitors in the solid-state Marx circuits, ten stages each, with an electrical equivalent circuit of the target, are presented, demonstrating both the improved voltage stability and pulse flexibility potential wanted for this new modulator.

7.
Rev Sci Instrum ; 78(3): 034702, 2007 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-17411205

RESUMO

This article discusses the operation of a modular generator topology, which has been developed for high-frequency (kHz), high-voltage (kV) pulsed applications. The proposed generator uses individual modules, each one consisting of a pulse circuit based on a modified forward converter, which takes advantage of the required low duty cycle to operate with a low voltage clamp reset circuit for the step-up transformer. This reduces the maximum voltage on the semiconductor devices of both primary and secondary transformer sides. The secondary winding of each step-up transformer is series connected, delivering a fraction of the total voltage. Each individual pulsed module is supplied via an isolation transformer. The assembled modular laboratorial prototype, with three 5 kV modules, 800 V semiconductor switches, and 1:10 step-up transformers, has 80% efficiency, and is capable of delivering, into resistive loads, -15 kV1 A pulses with 5 micros width, 10 kHz repetition rate, with less than 1 micros pulse rise time. Experimental results for resistive loads are presented and discussed.

8.
Rev. esp. investig. quir ; 10(1): 26-32, ene.-mar. 2007. tab, ilus
Artigo em Espanhol | IBECS | ID: ibc-87280

RESUMO

INTRODUCCIÓN: Los defectos óseos pueden ser debidos a anomalías congénitas, traumatismos, procesos infecciosos o tumorales,que a menudo se asocian a severos problemas funcionales y/o estéticos, que van a requerir un tratamiento complejo. El objetivo de este estudio fue comparar la formación de hueso nuevo tras la aplicación de una membrana reabsorbible y dos tipos de sustitutivos óseos. MATERIAL Y MÉTODO. Se utilizaron 24 ratas adultas machos tipo Wistar. Se crearon defectos circulares de 4 mm de diámetro en ambos lados de la mandíbula, y fueron divididos en 4 grupos: grupo I, grupo control con defectos vacíos; grupo II, los defectos fueron cubiertos con una membrana de hueso desmineralizado (Lambone®); grupo III, los defectos fueron rellenos con colágeno liofilizado bovino (Colloss®) y cubiertos con Lambone®; grupo IV, los defectos fueron rellenos con vidrio bioactivo (NovaBone®) y cubiertos con Lambone®. Los animales fueron sacrificados a las 3 y 6 semanas de la cirugía, realizándose un análisis radiológico e histológico. RESULTADOS. Los defectos control no mostraron formación ósea, apareciendo una reparación por tejido fibroso. La membrana de hueso utilizada de forma aislada, actuó como una barrera eficaz excluyendo los tejidos no osteogénicos, pero no se produjo reparación total del defecto en ningún caso. El grupo de Colloss® y membrana mostró una regeneración ósea completa del defecto a las 6 semanas. El grupo de NovaBone® y membrana no mostró formación ósea, apareciendo las partículas del biomaterial ocupando el defecto. CONCLUSIONES. La regeneración ósea fue significativamente mayor en los defectos rellenos con Colloss® y cubiertos con la membrana de Lambone®, comparado con los otros grupos experimentales (AU)


INTRODUCTION. Bony defects may be found as a result of congenital anomalies, trauma, neoplasms, or infectious conditions. uch conditions are often associated with severe funtional and esthetic problems. Corrective treatment is often complicated by limitations in tissue adaptations. The aim of this study was to compare the new bone formation following application of a bioabsorbable membrane and two types of bone substitutes. MATERIAL AND METHOD. In the present study, 24 4-month-old male Wistar rats were used. Standardized round through-and-through osseous defect (4 mm in diameter) was created similarly on both sides of the jaw and, were divided in four groups: group I, control defects were left empty; group II, the defects were covered with demineralized laminar bone membrane (Lambone®); group III, defects were filled with bovine bone collagen- protein extracts (Colloss®) and covered with Lambone®; group IV, defects were filled with bioactive glass (NovaBone®) and covered with Lambone®. Animals were killed 3 and 6 weeks after surgery, and healing of the bone defects was assessed by radiologic and histologic analysis. RESULTS. The control defects showed no bone formation, and the holes were filled with fibrous connective tissue. Bone membrane alone acted as an efficient barrier, excluding the nonosteogenic tissues, but new bone formation underneath the membrane was not full. The group of Colloss® and membrane showed complete healing after 6 weeks. The group of NovaBone® and membrane showed no bone formation, appearing the particles in the defect. CONCLUSION. A significantly higher percentage of bone regeneration was seen in the sites filled with Colloss® and covered with Lambone®, compared with the others experimental groups (AU)


Assuntos
Animais , Ratos , Regeneração Óssea/fisiologia , Mandíbula/fisiologia , Substitutos Ósseos/farmacocinética , Regeneração Tecidual Guiada/métodos , Desmineralização Patológica Óssea/cirurgia , Modelos Animais de Doenças , Membranas/fisiologia , Vidro , Colágeno/uso terapêutico
9.
Acta Otorrinolaringol Esp ; 52(4): 320-6, 2001 May.
Artigo em Espanhol | MEDLINE | ID: mdl-11526628

RESUMO

UNLABELLED: The aim of this study is to assess the feasibility of peripheral nerve allografts pretreated utilizing cold storage and cyclosporin A to improve the facial nerve regeneration in Wistar rat. Three groups were designed: Normal Wistar rats. 4 millimeters nerve gaps repaired with cryopreserved nerve allografts. 4 millimeters nerve gaps repaired with cryopreserved nerve grafts and treated with cyclosporin A. At 16 weeks post-engraftment the animals were evaluated: Facial palsy grading system. Electrophysiologic latency. Axonal counting. Nervous fiber area immediately distal to the graft. The facial function of the experimental groups was similar to the control rats while the latency and morphometric parameters was poor than the normal rats. CONCLUSIONS: 1. Cryopreserved nerve allografts in facial nerve repair in rats are useful in the aquisition of a facial functional nerve recovery as much in immunosuppressed animal as not. 2. Cryopreservation of nerve allografts results a good method of storage of nerve grafts. 3. Cyclosporin A immunosuppression improved not much the grading facial palsy in this model but the electrophysiologic and morphometry is significantly better.


Assuntos
Criopreservação/métodos , Ciclosporina/farmacologia , Nervo Facial/cirurgia , Paralisia Facial/cirurgia , Imunossupressão/métodos , Imunossupressores/farmacologia , Regeneração Nervosa/efeitos dos fármacos , Anastomose Cirúrgica/métodos , Animais , Ciclosporina/administração & dosagem , Nervo Facial/imunologia , Nervo Facial/ultraestrutura , Paralisia Facial/imunologia , Estudos de Viabilidade , Imunossupressores/administração & dosagem , Masculino , Ratos , Ratos Wistar , Transplante Homólogo
10.
An Otorrinolaringol Ibero Am ; 28(3): 244-54, 2001.
Artigo em Espanhol | MEDLINE | ID: mdl-11455882

RESUMO

The AA. after sever the facial nerve trunk of Wistar mice (so interrupting its path owing to the loss of about 4 mm of its anatomical continuity) repair the faulty portion with several grafts, and 4 months later consider the gained results achieved in each of the following parameters: functional, morphological, biochemical and electrophysiological and, finally, compare the own outcomes with bibliographic references of literature regarding this subject.


Assuntos
Modelos Animais de Doenças , Nervo Facial/fisiologia , Paralisia Facial , Regeneração Nervosa/fisiologia , Animais , Eletromiografia/métodos , Nervo Facial/fisiopatologia , Nervo Facial/cirurgia , Paralisia Facial/diagnóstico , Paralisia Facial/fisiopatologia , Paralisia Facial/cirurgia , Fibras Nervosas/fisiologia , Ratos , Ratos Wistar
14.
Acta Otorrinolaringol Esp ; 49(7): 513-7, 1998 Oct.
Artigo em Espanhol | MEDLINE | ID: mdl-9866215

RESUMO

An experimental model was developed for the purpose of investigating neural regeneration of the facial nerve in Wistar rats. The anatomic references used to locate the facial nerve at its exit from the skull base are described. A detailed description of the microsurgical anastomosis of cryopreserved nerve allografts is given. The major advantages and disadvantages of rat models compared with other animal models for experimental studies of the facial nerve are discussed.


Assuntos
Nervo Facial/cirurgia , Microcirurgia/métodos , Transplantes , Anastomose Cirúrgica/métodos , Animais , Masculino , Ratos , Ratos Wistar , Regeneração
15.
Int J Oral Maxillofac Surg ; 27(2): 92-3, 1998 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-9565262

RESUMO

A case of isolated unilateral temporalis muscle hypertrophy is presented. A review of the literature revealed only one report of temporalis hypertrophy, probably caused by psychogenic muscle hyperactivity. The temporalis muscle hypertrophy in the patient described was idiopathic and its management was surgical.


Assuntos
Músculo Temporal/patologia , Adolescente , Feminino , Humanos , Hipertrofia/cirurgia , Músculo Temporal/cirurgia
16.
Br J Oral Maxillofac Surg ; 35(3): 166-9, 1997 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-9212291

RESUMO

This prospective experimental study aimed to assess the regenerative capability of demineralised bone autografts resected and replaced orthotopically, compared with traditional fresh and deep frozen mandibular autografts in rats. In 60 adult Wistar rats, a bone defect 4 x 4 mm was created at the left ascending mandibular ramus and the removed bone was used as a fresh (n = 20), deep frozen (n = 20), or demineralised (n = 20) graft which was implanted orthotopically 2 weeks later. Ten rats in each group were killed at 2 and 6 weeks later. Outcome was measured by cellular proliferation on histological examination. The number of mesenchymal cells was significantly greater (P < 0.05) at both 2 and 6 weeks in the demineralised grafts than in the other two groups. There were no differences between the 2- and 6-week examinations of deep frozen bone, nor between the medullary and peripheral aspects. It was concluded that demineralised bony autografts cause greater osteoinduction both in the short (2 weeks) and the medium (6 weeks) term.


Assuntos
Transplante Ósseo/métodos , Doenças Mandibulares/cirurgia , Animais , Medula Óssea/patologia , Regeneração Óssea , Transplante Ósseo/patologia , Divisão Celular , Criopreservação , Técnica de Descalcificação , Seguimentos , Doenças Mandibulares/patologia , Mesoderma/patologia , Osteogênese , Estudos Prospectivos , Ratos , Ratos Wistar , Preservação de Tecido , Transplante Autólogo , Resultado do Tratamento
17.
Int J Oral Maxillofac Surg ; 24(6): 445-8, 1995 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-8636642

RESUMO

In an experimental model in the rat, a nonhealing bone defect was created in the left ascending mandibular ramus to test the effect of particulate porous hydroxyapatite (HA) on osteoinduction of demineralized bone autografts. The bone fragment removed was demineralized in HCl and used as an autograft for mandibular reconstruction. Granules of HA were added to the lingual and vestibular surfaces of the graft. The effect of this material was evaluated by determining the number of mesenchymal cells induced in the biomaterial and the central and peripheral zones of the bone graft, at 2-and 6-week intervals. The results show that the sites containing HA showed inhibition of osteoinduction by the bone matrix. In all groups, a proliferative gradient from the peripheral zone toward the center of the bone was observed. Similarly, the HA experienced a greater cellular increase in the regions in contact with the demineralized bone matrix.


Assuntos
Materiais Biocompatíveis/química , Substitutos Ósseos/química , Transplante Ósseo/fisiologia , Durapatita/química , Mandíbula/cirurgia , Osteogênese , Animais , Matriz Óssea/patologia , Matriz Óssea/fisiopatologia , Transplante Ósseo/patologia , Divisão Celular , Técnica de Descalcificação , Modelos Animais de Doenças , Mandíbula/patologia , Mandíbula/fisiopatologia , Doenças Mandibulares/cirurgia , Mesoderma/patologia , Osseointegração , Porosidade , Ratos , Ratos Wistar , Transplante Autólogo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA