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Determination of Threshold Dose of Photodynamic Therapy to Measure Superficial Necrosis

FERRAZ, R. C. M. C.; FERREIRA, J.; MENEZES, P. F. C.; SIBATA, C. H.; SILVA JR., O. Castro e; BAGNATO, V. S.
Fonte: MARY ANN LIEBERT INC Publicador: MARY ANN LIEBERT INC
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
47.82905%
Background Data: Photodynamic therapy (PDT) involves the photoinduction of cytotoxicity using a photosensitizer agent, a light source of the proper wavelength, and the presence of molecular oxygen. A model for tissue response to PDT based on the photodynamic threshold dose (Dth) has been widely used. In this model cells exposed to doses below Dth survive while at doses above the Dth necrosis takes place. Objective: This study evaluated the light Dth values by using two different methods of determination. One model concerns the depth of necrosis and the other the width of superficial necrosis. Materials and Methods: Using normal rat liver we investigated the depth and width of necrosis induced by PDT when a laser with a gaussian intensity profile is used. Different light doses, photosensitizers (Photogem, Photofrin, Photosan, Foscan, Photodithazine, and Radachlorin), and concentrations were employed. Each experiment was performed on five animals and the average and standard deviations were calculated. Results: A simple depth and width of necrosis model analysis allows us to determine the threshold dose by measuring both depth and surface data. Comparison shows that both measurements provide the same value within the degree of experimental error. Conclusion: This work demonstrates that by knowing the extent of the superficial necrotic area of a target tissue irradiated by a gaussian light beam...

Possibility for a full optical determination of photodynamic therapy outcome

VOLLET-FILHO, J. D.; MENEZES, P. F. C.; MORIYAMA, L. T.; GRECCO, C.; SIBATA, C.; ALLISON, R. R.; SILVA, O. Jr. Castro e; BAGNATO, V. S.
Fonte: AMER INST PHYSICS Publicador: AMER INST PHYSICS
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
57.722544%
The efficacy of photodynamic therapy (PDT) depends on a variety of parameters: concentration of the photosensitizer at the time of treatment, light wavelength, fluence, fluence rate, availability of oxygen within the illuminated volume, and light distribution in the tissue. Dosimetry in PDT requires the congregation of adequate amounts of light, drug, and tissue oxygen. The adequate dosimetry should be able to predict the extension of the tissue damage. Photosensitizer photobleaching rate depends on the availability of molecular oxygen in the tissue. Based on photosensitizers photobleaching models, high photobleaching has to be associated with high production of singlet oxygen and therefore with higher photodynamic action, resulting in a greater depth of necrosis. The purpose of this work is to show a possible correlation between depth of necrosis and the in vivo photosensitizer (in this case, Photogem (R)) photodegradation during PDT. Such correlation allows possibilities for the development of a real time evaluation of the photodynamic action during PDT application. Experiments were performed in a range of fluence (0-450 J/cm(2)) at a constant fluence rate of 250 mW/cm(2) and applying different illumination times (0-1800 s) to achieve the desired fluence. A quantity was defined (psi) as the product of fluorescence ratio (related to the photosensitizer degradation at the surface) and the observed depth of necrosis. The correlation between depth of necrosis and surface fluorescence signal is expressed in psi and could allow...

Analysis of the combined effect of lasers of different wavelengths for PDT outcome using 600, 630, and 660 nm

ATIF, M.; FAKHAR-E-ALAM, M.; SABINO, L. G.; IKRAM, M.; ARAUJO, M. T. de; KURACHI, Cristina; BAGNATO, Vanderlei Salvador; ALSALHI, M. S.
Fonte: WILEY-BLACKWELL Publicador: WILEY-BLACKWELL
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
47.59636%
We investigated the effects of photodynamic therapy (PDT) outcome when combining three laser systems that produce light in three different wavelengths (600, 630, and 660 nm). Cooperative as well as independent effects can be observed. We compared the results of the combined wavelengths of light with the effect of single laser for the excitation of the photosensitizer. In the current experiment, the used photosensitizer was Photogem (R) (1.5 mg/kg). Combining two wavelengths for PDT, their cumulative dose and different penetrability may change the overall effect of the fluence of light, which can be effective for increasing the depth of necrosis. This evaluation was performed by comparing the depth and specific aspect of necrosis obtained by using single and dual wavelengths for irradiation of healthy liver of male Wistar rats. We used 15 animals and divided them in five groups of three animals. First, Photogem (R) was administered; follow by measurement of the fluorescence spectrum of the liver before PDT to confirm the level of accumulation of photosensitizer in the tissue. After that, an area of 1 cm(2) of the liver was illuminated using different laser combinations. Qualitative analysis of the necrosis was carried out through histological and morphological study. [GRAPHICS] (a) - microscopic images of rat liver cells...

Aggregation susceptibility on phototransformation of hematoporphyrin derivatives

MENEZES, P. F. C.; IMASATO, H.; FERREIRA, J.; BAGNATO, Vanderlei Salvador; SIBATA, C. H.; PERUSSI, J. R.
Fonte: WILEY-V C H VERLAG GMBH Publicador: WILEY-V C H VERLAG GMBH
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
47.22838%
Photosensitizers used in PDT suffer degradation by light. In this work, photobleaching of Photogem((R)) (PG), Photofrin((R)) (PF), and Photosan((R)) (PS), hematoporphyrin derivatives, were induced by light in the presence or absence of 1% Triton X-100. The degradation efficiency in the absence of 1% Triton X-100 follows the sequence: Pf > PF > Ps, which means that PF presented a greater degradation than PF and PS. Forever, in the presence of the surfactant the degradation efficiency is different: PF congruent to PS > PF. Besides aggregation susceptibility, studies in cell culture (tumor and non tumor cells) and in animals (depth of necrosis) were performed, trying to correlate the stability of these photosensitizers with their photodynamic effect. The results suggest that PF presents higher light induced photo-cytotoxicity than PF and PS for both types of cells. For the depth of necrosis studies, more aggregated photosensitizer showed a longer time to accumulate in liver (30 min for PG, 120 h for PF and 720 h for PS). The, to establish an ideal dosimetry in PDT, one must consider the intrinsic physical chemistry characteristics of the photosensitizer as well as their ability to undergo photobleaching.

Non-homogeneous liver distribution of photosensitizer and its consequence for photodynamic therapy outcome

VOLLET-FILHO, Jose Dirceu; CARACANHAS, Monica Andrioli; GRECCO, Clovis; FERREIRA, Juliana; KURACHI, Cristina; BAGNATO, Vanderlei Salvador
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
47.23291%
Background: Photodynamic therapy is mainly used for treatment of malignant lesions, and is based on selective location of a photosensitizer in the tumor tissue, followed by light at wavelengths matching the photosensitizer absorption spectrum. In molecular oxygen presence, reactive oxygen species are generated, inducing cells to die. One of the limitations of photodynamic therapy is the variability of photosensitizer concentration observed in systemically photosensitized tissues, mainly due to differences of the tissue architecture, cell lines, and pharmacokinetics. This study aim was to demonstrate the spatial distribution of a hematoporphyrin derivative, Photogem(R), in the healthy liver tissue of Wistar rats via fluorescence spectroscopy, and to understand its implications on photodynamic response. Methods: Fifteen male Wistar rats were intravenously photosensitized with 1.5 mg/kg body weight of Photogem(R). Laser-induced fluorescence spectroscopy at 532nm-excitation was performed on ex vivo liver slices. The influence of photosensitizer surface distribution detected by fluorescence and the induced depth of necrosis were investigated in five animals. Results: Photosensitizer distribution on rat liver showed to be greatly non-homogeneous. This may affect photodynamic therapy response as shown in the results of depth of necrosis. Conclusions: As a consequence of these results...

Evidence of 5-aminolevulinic acid (ALA) penetration increase due to microdrilling in soft tissue using femtosecond laser ablation

Nicolodelli, Gustavo; Kurachi, Cristina; Rego, Raquel Ferreira; Omairi, Tarek; Bagnato, Vanderlei Salvador
Fonte: SPRINGER LONDON LTD; LONDON Publicador: SPRINGER LONDON LTD; LONDON
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
57.466294%
Photodynamic therapy (PDT) is a therapeutic technique mainly applied to the treatment of malignant and pre-malignant lesions, which induces cell death by the combined effect of a photosensitizer, irradiation in a proper wavelength, and molecular oxygen. One of the main limitations of PDT using 5-aminolevulinic acid (ALA) is the superficial volume of treatment, mainly due to the limited penetration of topical photosensitization. In this context, the present study investigates if a laser micromachining producing microchannels on the tissue surface could improve ALA penetration and result in an increase in the treatment depth. The laser micromachining under femtosecond regime was performed on the tissue surface of rat livers. Conventional PDT was applied and the induced depth of necrosis with or without laser micromachining was compared. The results showed an increase of more than 20% in the depth of necrosis when the femtosecond laser micromachining was performed before the treatment with the PDT.; FAPESP (CEPOF/CEPID Program); FAPESP (CEPOF/CEPID Program); CNPq (INCT Program); CNPq (INCT Program); CAPES; CAPES

Necrosis response to photodynamic therapy using light pulses in the femtosecond regime

Grecco, Clóvis; Moriyama, Lilian Tan; Cosci, Alessandro; Pratavieira, Sebastião; Bagnato, Vanderlei Salvador; Kurachi, Cristina
Fonte: Springer; London Publicador: Springer; London
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
77.478877%
One of the clinical limitations of the photodynamic therapy (PDT) is the reduced light penetration into biological tissues. Pulsed lasers may present advantages concerning photodynamic response when compared to continuous wave (CW) lasers operating under the same average power conditions. The aim of this study was to investigate PDT-induced response when using femtosecond laser (FSL) and a first-generation photosensitizer (Photogem) to evaluate the induced depth of necrosis. The in vitro photodegradation of the sensitizer was monitored during illumination either with CWor an FSL as an indirect measurement of the PDT response. Healthy liver of Wistar rats was used to evaluate the tissue response. The photosensitizer was endovenously injected and 30 min after, an energy dose of 150 Jcm-2 was delivered to the liver surface. We observed that the photodegradation rate evaluated via fluorescence spectroscopy was higher for the FSL illumination. The FSL-PDT produced a necrosis nearly twice as deep when compared to the CW-PDT. An increase of the tissue temperature during the application was measured and was not higher than 2.5 °C for the CW laser and not higher than 4.5 °C for the pulsed laser. FSL should be considered as an alternative in PDT applications for improving the results in the treatment of bulky tumors where higher light penetration is required.; CAPES; CNPq; FAPESP

In vivo study of necrosis on the liver tissue of Wistar rats: a combination of photodynamic therapy and carbon dioxide laser ablation

Rego, R. F.; Nicolodelli, G.; Araujo, M. T.; Tirapelli, Luis Fernando; Moreira, F. M. Araujo; Bagnato, Vanderlei Salvador
Fonte: Institute of Physics - IOP; Bristol Publicador: Institute of Physics - IOP; Bristol
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
66.954277%
Photodynamic therapy (PDT) is known to be limited to applications in large volume tumors due to its limited penetration. Therefore, a combination of PDT and carbon dioxide (CO2) laser ablation may constitute a potential protocol to destroy bulk tumors because it involves an association of these two techniques allowing the removal of visible lesions with a high selectivity of destruction of remnant tumors. The main aim of this study is to investigate the most appropriate procedure to combine use of a CO2 laser and PDT on livers of healthy rats, and to analyze different techniques of this treatment using three types of photosensitizers (PSs).Forty eight animals were separated to form six groups: (1) only CO2 laser ablation, (2) drug and CO2 laser ablation, (3) only PDT, (4) drug and light (PDT) followed by CO2 laser ablation, (5) ablated with CO2 laser followed by PDT, and (6) drug followed by CO2 laser ablation and light. For each group, three types of photosensitization were used: topical 5-aminolevulinic acid (ALA), intravenous ALA and intravenous Photogem®. Thirty hours after the treatments, the animals were sacrificed and the livers removed. The depth of necrosis was analyzed and measured, considering microscopic and macroscopic aspects. The results show that the effects of the PDT were considerably enhanced when combined with CO2 laser ablation...

"Estudos espectroscópicos e citotóxicos do Photogem® fotodegradado e dos fotoprodutos formados pela irradiação com laser"; "Spectroscopics and cytotoxics studies of Photogem® photodegradate and of photoproducts formated by irradiation with laser"

Menezes, Priscila Fernanda Campos de
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 01/09/2006 PT
Relevância na Pesquisa
47.84922%
A Terapia Fotodinâmica (TFD) é uma técnica para induzir dano ao tecido tumoral e consiste na administração de uma droga fotossensível que pode ser seletivamente retida no tecido tumoral e que produz oxigênio singlete quando irradiada em comprimento de onda adequado na presença de oxigênio molecular. Fotossensibilizadores do tipo porfirinas podem ser degradados pela luz modificando a concentração do fotossensibilizador (FS) no tumor. Este processo chamado de fotodegradação caracteriza-se pela diminuição nas intensidades das bandas de absorbância e fluorescência e pode ser acompanhado pela formação de fotoprodutos. Neste estudo o FS usado foi Photogem®, um derivado de hematoporfirina produzido na Rússia e que está sendo usado em TFD no Brasil. A fotodegradação do sensibilizador e formação de fotoprodutos foi monitorada pelas mudanças nas propriedades de fluorescência e absorbância, assim como pela formação do fotoproduto evidenciado pelo aparecimento de uma nova banda em torno de 640nm em PBS e 660nm em soluções de Triton X-100 e Brij-35. A fotodegradação do Photogem® e a formação dos fotoprodutos foram induzidas pela irradiação com laser e LED em diferentes concentrações, comprimentos de ondas de irradiação (351...

"Correlação entre bioquímica celular e necrose tecidual em regimes de fracionamento de dose de luz em terapia fotodinâmica"; Correlation between cellular biochemistry and tecidual necrosis in light fractionation on photodynamic tehrapy

Bonini, Daniel
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 30/06/2006 PT
Relevância na Pesquisa
47.697183%
Terapia fotodinâmica (TFD) é uma modalidade terapêutica pouco invasiva e sem efeitos térmicos aprovada para o tratamento de doenças neoplásicas e vasculares proliferativas, capaz de produzir necrose tecidual seletiva através de administração de um fármaco fotossensibilizador seguido da aplicação de luz em comprimento de onda adequado. Na presença de luz o fotossensibilizador passa à forma ativada, e na presença de oxigênio molecular presente nas células, produz espécies reativas de oxigênio e oxigênio singleto que induzem as células alteradas à morte. O melhor entendimento dos mecanismos e da resposta celular à TFD, a disponibilidade de fontes de luz mais baratas, confiáveis e de fácil manuseio, bem como bons resultados em pesquisa clínica, dão credibilidade à técnica e a sua difusão na prática clínica. Estudos recentes em dosimetria têm mostrado melhores resultados terapêuticos com o fracionamento da dose de luz uma vez que permite a reoxigenação dos tecidos durante o período em que esse não está sendo iluminado. Neste estudo, investigou-se o dano tecidual (profundidade de necrose) e os danos celulares, especificamente na mitocôndria (estado 3, estado 4, taxa do controle respiratório, relação de ADP/O...

Avaliação da resposta fotodinâmica em fígado normal de ratos utilizando fonte de luz pulsada no regime de femtossegundos; Evaluation of photodynamic response in normal rat liver using a femtosecond regime pulsed irradiation

Grecco, Clovis
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 13/02/2009 PT
Relevância na Pesquisa
47.62553%
A terapia fotodinâmica (TFD) é uma promissora técnica para o tratamento de câncer e de outras patologias. O tratamento baseia-se na ação de uma fonte de luz com o agente fotossensibilizador (FS) e o oxigênio molecular presente nas células, gerando espécies reativas de oxigênio que causam a morte celular. Uma das limitações atuais da técnica é a penetração da luz no tecido biológico. Entre os fotossensibilizadores mais empregados, estão os derivados de hematoporfirina, que são excitados da região do vermelho do espectro eletromagnético. Fotossensibilizadores vêm sendo desenvolvidos para iluminação com comprimentos de onda maiores, com o potencial de aumentar a profundidade de penetração e em conseqüência, o volume tecidual tratado. Outra opção para aumentar o volume tecidual de resposta utilizando derivados de hematoporfirina é a utilização de fontes de luz pulsada que, em comparação com a contínua, vem apresentado resultados significativos no estudo da TFD. Neste estudo, foi realizada a fotodegradação in vitro do fotossensibilizador comercial Photogem® (Moscou, Rússia) com tempos variando entre 0 e 40 minutos. Como fonte de luz contínua foi utilizado um laser de diodo (Eagle Heron Quantum Tech...

Correlação de fluorescência superficial e profundidade de necrose em terapia fotodinâmica: possibilidade de dosimetria em tempo real; Correlation of surface fluorescence and depth of necrosis in photodynamic therapy: possibility for real-time dosimetry

Vollet Filho, José Dirceu
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 11/11/2011 PT
Relevância na Pesquisa
97.84673%
O tratamento do câncer e de lesões pré-malignas é uma importante aplicação da terapia fotodinâmica. A base da técnica é o uso da luz associada a um fotossensibilizador, na presença de oxigênio, de forma a promover a formação de espécies reativas de oxigênio que culminam na morte celular. Esta técnica é altamente seletiva, e apresenta poucos efeitos colaterais. A efetividade da terapia pode ser avaliada com base na emissão de fluorescência do fotossensibilizador, uma vez que o grau de fotodegradação deste indica uma terapia mais ou menos efetiva. No caso de tumores, a reincidência de lesões, causada por células malignas remanescentes, é um problema importante e que pode piorar as condições clínicas de um paciente. Este estudo propõe, portanto, um modelo matemático baseado na aferição da fluorescência do fotossensibilizador in situ para previsão da extensão do dano promovido pela terapia fotodinâmica em tempo real. Esta aferição é feita em comparação com o parâmetro experimental de profundidade de necrose, de modo a avaliar se uma lesão pode ser completamente eliminada numa dada aplicação. O estudo utilizou fígados de ratos Wistar machos, saudáveis, como modelo inicial dada sua relativa homogeneidade óptica com relação a lesões tumorais...

Estudo comparativo da terapia fotodinâmica utilizando laser CW e de femtossegundos em diferentes intensidades e comprimentos de onda; Comparative study of photodynamic therapy using CW and femtosecond laser at different intensities and wavelengths

Grecco, Clovis
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 28/11/2013 PT
Relevância na Pesquisa
47.73887%
A terapia fotodinâmica (TFD) é uma modalidade de tratamento para o câncer baseado na interação da luz com um agente fotossensibilizador (FS) e o oxigênio molecular presente na célula alvo. A TFD apresenta vantagens sobre os métodos tradicionais de tratamentos como o dano seletivo às células neoplásicas, ausência de intervenção cirúrgica, possibilidade de repetição do procedimento e efeitos colaterais controlados. Uma das limitações da técnica é a profundidade de pouca penetração da luz no tecido biológico e consequentemente o volume tecidual tratado. Uma alternativa para superar esta limitação é o emprego de fonte de luz pulsada que comparativamente a irradiação com luz contínua (CW), apresenta maior potência de pico levando a uma maior profundidade de penetração e maior formação de espécies reativas de oxigênio. O objetivo deste trabalho é a avaliação da TFD utilizando fonte de luz pulsada no regime de femtossegundos através de ensaios in vitro da fotodegradação de dois tipos de FSs e da necrose induzida em fígado sadio de ratos (estudos in vivo). Nos estudos in vitro foram avaliadas a fotodegradação do Photogem (PG - 8μg/mL) e do Photodithazine (PDZ - 6μg/mL), para as irradiâncias de 280...

Reversal of Capillary Stasis and Prevention of Necrosis in Burns

Zawacki, Bruce E.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /07/1974 EN
Relevância na Pesquisa
47.86596%
It has been suggested that the ultimate depth of burn necrosis might be minimized by prevention or reversal of the progressive capillary stasis which occurs in the early postburn hours. To study the role of wound dehydration in determining burn depth, 5% body surface area, 75 C, 10 second burns (in which the zone of stasis included the full thickness of skin) were inflicted on the backs of guinea pigs and subsequent mechanical trauma was prevented. At various times postburn, water content, (and after India ink perfusion) depth of capillary stasis and histological structure of burn were studied in the following groups: 1) blister intact; 2) blister removed; and 3) blister replaced by several different types of dressing. Reversal of capillary stasis was least and necrosis full-thickness in depth in undressed wounds with blister removed. Reversal of capillary stasis was complete and necrosis absent with blister replaced by fresh split-thickness porcine skin and correlated with prevention of wound dehydration. Similar, though less complete, prevention of necrosis occurred with blister intact or replaced by sialastic film. Other dressings were associated with deep necrosis or gross infection. These and other data suggest that in the zone of stasis...

Local eradication of rat colon cancer with photodynamic therapy: correlation of distribution of photosensitiser with biological effects in normal and tumour tissue.

Barr, H; Chatlani, P; Tralau, C J; MacRobert, A J; Boulos, P B; Bown, S G
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/1991 EN
Relevância na Pesquisa
46.957036%
Photodynamic therapy is a photochemical technique for the local destruction of tumours, entailing the interaction of light with an administered photosensitiser to produce a cytotoxic effect. We investigated the tissue distribution of the photosensitiser aluminium sulphonated phthalocyanine (AlSPc) in dimethylhydrazine induced colonic tumours and adjacent normal colon in rats. Forty eight hours after intravenous injection, most tumours contained twice as much AlSPc as normal colon. Tumour size and position in the colon did not affect AlSPc concentration. Microscopic fluorescence localisation of AlSPc showed significant photosensitiser accumulation in tumour stroma, whereas tumour and normal mucosa contained similar amounts. Thus, some normal tissue damage, where malignant cells invade normal areas, would inevitably accompany eradication of tumours. Tumour destruction and healing of colon after tumour eradication were examined histologically. There was sharp demarcation between necrotic areas (tumour or normal) and adjacent tissue and, whether the treated area was tumour or normal, healing occurred by regeneration of normal tissue. Some incompletely eradicated large tumours showed evidence of delayed bleeding. The possibility of selective uptake or preferential retention of the photosensitiser in tumours formed the initial basis for investigation of photodynamic therapy...

In vitro comparison of the vaporesection of human benign prostatic hyperplasia using 70- and 120-W 2-µm lasers

Luo, Guang-Heng; Xia, Shu-Jie; Sun, Zhao-Lin
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
47.08029%
The purpose of the current ex vivo study was to compare the speed of vaporesection of human prostatic tissue with benign prostatic hyperplasia (BPH) and the depth of tissue damage using 70- and 120-W 2-µm laser devices. Fresh prostatic tissue specimens were obtained from five patients by open prostatectomy, and were divided into separate groups (70 and 120 W) based on the energy of the laser output (70 and 120 W, respectively). The vaporesection speed, coagulation zone depth and the necrotic tissue layer in the prostatic tissue were evaluated. The current result showed that the speeds (mean±s.d.) of vaporesection were 5.21±0.66 and 10.39±1.15 g/5 min for the 70 and 120 W groups, respectively (P=0.000). There was no difference in the depth of necrosis/coagulation (0.98±0.13/0.30±0.09 and 0.99±0.12/0.31±0.08 mm) for the 70 and 120 W groups, respectively. In conclusion, both 70- and 120-W 2-µm laser devices had superficial tissue damage during the vaporesection of human prostate tissue; moreover, the 120-W laser offers a higher vaporesection speed than the 70-W laser.

Caracterização de novas espécies de Streptomyces associadas à sarna da batata no Brasil; Characterization of new Streptomyces species associated with potato scab in Brazil

Daniele Bussioli Alves Corrêa
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 24/07/2015 PT
Relevância na Pesquisa
46.957866%
A sarna da batata é uma doença de ocorrência generalizada nas regiões produtoras do Brasil, tornando-se um fator limitante no cultivo dessa cultura. Essa doença afeta a qualidade da batata por lesões na superfície do tubérculo, que diminuem seu valor comercial ou impedem a comercialização. Diferentes espécies do gênero Streptomyces são causadoras dessa doença e o levantamento das espécies patogênicas presentes em regiões produtoras do Brasil é um fator primordial para a realização de medidas de manejo. O presente trabalho teve por objetivo a caracterização de 57 linhagens de Streptomyces, consideradas possíveis novas espécies associadas à sarna da batata no Brasil, por meio de taxonomia polifásica. Foi realizada a caracterização morfológica, bioquímica, patogênica (genes nec1, tomA e txtAB e testes de patogenicidade in vitro em rabanete e batata) e molecular (primers específicos para S. acidiscabies, S. scabiei e S. turgidiscabies, PCR-RFLP do gene atpD, análises de multilocus - genes atpD, gyrB, recA, rpoB, trpB e do gene 16S RNAr) das linhagens. Utilizando-se as técnicas de PCR-RFLP do gene atpD e análise de sequências dos genes atpD e rpoB as linhagens foram, inicialmente, separadas em 20 grupos genéticos (G1 a G20). Esses grupos apresentaram alta heterogeneidade com relação à morfologia da cadeia de esporos...

Symptomatology and Histopathology of Soybean Roots Infected by Pratylenchus scribneri and P. alleni

Acosta, Nelia; Malek, R. B.
Fonte: Society of Nematologists Publicador: Society of Nematologists
Tipo: Artigo de Revista Científica
Publicado em /01/1981 EN
Relevância na Pesquisa
46.953164%
Size of lesions caused by Pratylenchus scribneri on roots of 'Clark 63' soybean was correlated with nematode colony size within roots. A single nematode was capable of causing a detectable lesion. When a root became highly necrotic and shrunken, few nematodes but numerous eggs remained in the tissue. In histological sections made 5, 11, 18, and 45 d after planting, P. scribneri was located entirely within the cortex and generally was oriented longitudinally to the vascular cylinder, either outstretched in the same plane or coiled through several cells. Nematodes moved intracellularly, causing extensive rupturing of cell walls, retraction and disappearance of cytoplasm, and thickening of cell walls and necrosis of cells around feeding sites. Depth of penetration within the cortex and necrosis of cells increased with time after infection, eventually resulting in formation of cavities in the cortex and occasional secondary injury to the endodermis. Stele tissue was unaffected by feeding, and damage to the epidermis was limited to nematode entry points. Orientation of P. alleni and histopathology of its infection at 45 days were identical to those of P. scribneri, except that there was no injury to the endodermis.

In vivo magnetic resonance imaging of the effects of photodynamic therapy.

Dodd, N. J.; Moore, J. V.; Poppitt, D. G.; Wood, B.
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em /08/1989 EN
Relevância na Pesquisa
46.948633%
Nuclear magnetic resonance (NMR) proton imaging and measurements of the parameters T1 and T2, have been carried out in vivo on the murine mammary tumour T50/80. Tumours had been treated 24 h previously by photodynamic therapy (PDT, using haematoporphyrin derivative and 630 nm laser light). Proton images clearly demarcated a high signal-intensity region on the side of the tumour closest to the incident light beam, while the parts of the tumour more remote from the beam resembled the images from untreated controls. Both T1 and T2 values were raised in the high-intensity region. This high-intensity region was shown to correspond to PDT-induced histological necrosis, the low-intensity region to histologically intact tumour. Linear regression analysis of the relationship of depth of necrosis measured histologically and 'depth of necrosis' measured from the NMR images, yielded a slope of 0.93 (r2 = 0.95).

Ossification of the N-methyl-N'-nitro-N-nitrosoguanidine-induced small intestine adenocarcinomas in rats.

Kim, W. H.; Kim, Y. I.
Fonte: Korean Academy of Medical Sciences Publicador: Korean Academy of Medical Sciences
Tipo: Artigo de Revista Científica
Publicado em /12/1991 EN
Relevância na Pesquisa
46.954746%
Eighty rats out of 233 developed malignant tumors in the stomach and small intestine by administration of 100 micrograms/ml N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in drinking water for 28 weeks. Fifteen lesions (30%) among the 50 small intestinal carcinomas showed ossification in the tumor, while none in the sarcomas (12 lesions) or gastric adenocarcinomas (59 lesions) showed ossification. Multifocal heterotopic bone formation was found within stroma in close approximation to the neoplastic glands. The islands of bone trabeculae were covered by osteoblast-like cells, and abundant fibroblasts in loose stroma gathered around the bony islands which enclosed osteocytes in lacunae. Neither osteoclast nor cartilage was identified. In 5 cases, ossification was extensive, which comprised the major portion of the stroma. In contrast, intraluminal calcification without ossified foci were occasionally seen in the gastric carcinoma. Ossification of the intestinal tumors correlated to the degree of mucin content (p < 0.05, chi square with Yates' correction), degree of neutrophilic infiltration (p < 0.05), and size of the tumor (p < 0.1). (The average size of the ossified tumor was 21.5 +/- 4.0 mm, while that of nonossified tumors was 12.5 +/- 1.9 mm). The degree of tumoral necrosis...