Development of a low-cost simulator for training in hemorrhoidal ligation

Introduction: Rubber band ligation is a minimally invasive outpatient hemorrhoid treatment with low cost, low complication rates, and rapid realization. It is performed with the aid of an anoscope and uses a rubber ring that surrounds the hemorrhoidal nipple, causing compression of the vascular structures of the tissue, leading to necrosis and remission of the hemorrhoid. No device for training this essential procedure for treating this pathology has been identified in the literature. Therefore, we aim to develop a low-cost simulator for training hemorrhoidal rubber ligation. Methods: The model was constructed using PVC pipe wrapped in neoprene fabric. Hemorrhoidal nipples and the pectineal line were also simulated using fabric and sewing threads. The procedure is performed with conventional anoscope and ligature forceps. Conclusion: The device in question is a low-cost simulation model designed to train the skills required to perform a rubber band ligation and review the basic anatomy of the anal canal during anoscopy. Given these qualities, the model can be used for academic training due to its low cost and simplicity of application. (AU)

Construction and application of a low-cost laparoscopy training simulator as a teaching tool through motor coordination and two-dimensional vision practices.

OBJECTIVES: to describe the construction of a low-cost laparoscopy training simulator and evaluate its level of acceptance, impact on learning, and skill development in medical students. METHODS: we built a video training simulator using low-cost materials. We then carried out a cross-sectional study, with the use of an applied questionnaire to medical students. RESULTS: 51 medical students participated in the research, of whom 76.47% gained confidence in relation to laparoscopic surgery, 100% stated that the model successfully trained the skills of motor coordination and two-dimensional visual-spatial field, in addition to enabling a greater understanding of laparoscopy. All agreed that the simulator should be used before a real laparoscopic surgery scenario. CONCLUSION: the construction of the described laparoscopic surgery training simulator proved to be feasible and effective as an educational resource. It was well accepted by medical students, with easy handling, and promoted the development of motor and visual skills in video surgery.

Assembly and use of a low-cost paracentesis simulator for the teaching of puncture and drainage of ascites.

OBJECTIVES: to describe the assembly of a low-cost paracentesis simulator and evaluate its effectiveness, acceptance and impact on the learning of medical students. METHODOLOGY: a paracentesis simulator was built using a mannequin and materials such as plastic bottles, Velcro, polyvinyl chloride sheets and silicone were used. A cross-sectional and experimental study was carried out with undergraduate medical students without previous practical experience with paracentesis, which sought to validate the model, evaluating its benefits in learning and obtaining technical skills. RESULTS: after using the simulator there was an increase of 82.4% in the level of confidence in performing paracentesis in a patient, with 98% of respondents considering that the model fulfilled the simulator function with satisfaction, and 100% considering it useful as a teaching tool. CONCLUSION: the built simulator was effective as an educational resource, serving as an alternative to high-cost commercial models, allowing for greater accessibility in the use of this tool in medical education.

Construction and application of a low-cost laparoscopy training simulator as a teaching tool through motor coordination and two-dimensional vision practices / Construção e aplicação de simulador de videotreinamento de baixo custo como ferramenta de ensino por meio de práticas de coordenação motora e experiência com visão bidimensional

ABSTRACT Objectives: to describe the construction of a low-cost laparoscopy training simulator and evaluate its level of acceptance, impact on learning, and skill development in medical students. Methods: we built a video training simulator using low-cost materials. We then carried out a cross-sectional study, with the use of an applied questionnaire to medical students. Results: 51 medical students participated in the research, of whom 76.47% gained confidence in relation to laparoscopic surgery, 100% stated that the model successfully trained the skills of motor coordination and two-dimensional visual-spatial field, in addition to enabling a greater understanding of laparoscopy. All agreed that the simulator should be used before a real laparoscopic surgery scenario. Conclusion: the construction of the described laparoscopic surgery training simulator proved to be feasible and effective as an educational resource. It was well accepted by medical students, with easy handling, and promoted the development of motor and visual skills in video surgery.

RESUMO Objetivos: descrever a construção de um simulador de treinamento de videocirurgia de baixo custo e avaliar, por meio de sua aplicação, o nível de aceitação, de impacto no aprendizado e de desenvolvimento de habilidades em acadêmicos do curso de medicina. Método: foi construído um simulador, de videotreinamento com uso de materiais de baixo custo. Realizou-se um estudo transversal com a utilização de questionário aplicado a acadêmicos do curso de medicina. Resultados: a pesquisa contou com a participação de 51 acadêmicos de medicina. Após o uso do simulador 76,47% dos pesquisados adquiriram confiança em relação à videocirurgia, 100% afirmaram que o modelo treinou com satisfação as habilidades de coordenação motora e campo visoespacial bidimensional, além de possibilitar maior compreensão da videocirurgia. Todos concordaram que o simulador deveria ser utilizado antes da situação real. Conclusão: a construção do simulador de treinamento em videocirurgia descrito mostrou-se factível e eficaz como recurso educacional. Obteve boa aceitação pelos acadêmicos, com fácil manuseio, capaz de fomentar o desenvolvimento das habilidades motoras e visuais em videocirurgia.

Assembly and use of a low-cost paracentesis simulator for the teaching of puncture and drainage of ascites / Montagem e uso de simulador de paracentese de baixo custo - aplicabilidade no ensino de punção e drenagem de ascite

ABSTRACT Objectives: to describe the assembly of a low-cost paracentesis simulator and evaluate its effectiveness, acceptance and impact on the learning of medical students. Methodology: a paracentesis simulator was built using a mannequin and materials such as plastic bottles, Velcro, polyvinyl chloride sheets and silicone were used. A cross-sectional and experimental study was carried out with undergraduate medical students without previous practical experience with paracentesis, which sought to validate the model, evaluating its benefits in learning and obtaining technical skills. Results: after using the simulator there was an increase of 82.4% in the level of confidence in performing paracentesis in a patient, with 98% of respondents considering that the model fulfilled the simulator function with satisfaction, and 100% considering it useful as a teaching tool. Conclusion: the built simulator was effective as an educational resource, serving as an alternative to high-cost commercial models, allowing for greater accessibility in the use of this tool in medical education.

RESUMO Objetivos: descrever a montagem de simulador de paracentese de baixo custo e avaliar eficácia, aceitação e impacto no aprendizado de acadêmicos do curso de medicina. Método: um simulador de paracentese foi construído a partir de manequim e de materiais como garrafas plásticas, velcro, folhas de policloreto de vinila e silicone. Foi feito estudo transversal com estudantes da graduação do curso de medicina sem experiência real prévia com paracentese, que buscou validar o modelo, por meio da análise de benefícios no aprendizado e na obtenção de habilidades técnicas. Resultados: após o uso do simulador, observou-se aumento de 82,4% no nível de segurança na realização da paracentese em paciente, 98% dos pesquisados consideraram que o uso do modelo cumpriu com satisfação a função de simulador e 100% definiram-no útil como ferramenta de ensino. Conclusão: a montagem do simulador mostrou-se factível e eficaz como recurso educacional. Serviu como alternativa aos modelos comerciais de alto custo e permitiu maior acessibilidade do uso dessa ferramenta na educação médica.

O ultrassom anorretal tridimensional pode ser incluído como um método diagnóstico na avaliação da fístula anal antes e após o tratamento cirúrgico? / Can three-dimensional anorectal ultrasonography be included as a diagnostic tool for the assessment of anal fistula before and after surgical treatment?

ABSTRACT BACKGROUND: There is no a clear knowledge concerning the division of any part of the anal sphincter complex and the effect of this procedure on the function of the anal canal during the treatment of perianal fistula. OBJECTIVE: To evaluate the usefulness of 3D anorectal ultrasound in the assessment of anal fistula, quantifying the length of the sphincter muscle to be transected, selecting patients for different approaches and identifying healing, failure or recurrence after the surgical treatment. METHODS: A prospective study included patients with primarily cryptogenic transsphincteric anal fistula assessed by fecal Incontinence score, tri-dimensional anorectal ultrasound and anal manometry before and after surgery. Based on 3D-AUS, patients with ≥50% external sphincter or external sphincter+puborectalis muscle involvement in males and ≥40% external sphincter or external sphincter+puborectalis muscle in females were referred for the ligation of the intersphincteric tract (LIFT) or seton placement and subsequent fistulotomy; and with <50% involvement in males and <40% in females were referred to one-stage fistulotomy. After surgery, the fibrosis (muscles divided) and residual muscles were measured and compared with the pre-operative. RESULTS: A total of 73 patients was included. The indication for the LIFT was significantly higher in females (47%), one-stage fistulotomy was significantly higher in the males (46%) and similar in seton placement. The minor postoperative incontinence was identified in 31% of patients underwent sphincter divided and were similar in both genders. The 3D-AUS identified seven failed cases. CONCLUSION: The 3D ultrasound was shown to be an effective method in the preoperative assessment of anal fistulas by quantifying the length of muscle to be divided, as the results were similar at the post-operative, providing a safe treatment approach according to the gender and percentage of muscle involvement. Additionally, 3D ultrasound successfully identified the healing tissue and the type of failure or recurrence.

RESUMO CONTEXTO: Não há dados definitivos quanto a níveis diferentes na secção do complexo esfincteriano e o efeito na função do canal anal no tratamento das fístulas anais. OBJETIVO: Avaliar a aplicação do ultrassom anorretal tridimensional no diagnóstico da fístula anal, quantificando o comprimento da musculatura que será seccionada, selecionando pacientes para diferente abordagens e identificando cicatrização e recorrência após tratamento. MÉTODOS: Um estudo prospectivo incluindo paciente portadores de fístula anal criptoglandular, tipo trans-esfinctérica avaliados pelo escore de incontinência fecal, ultrassom anorretal 3D e manometria anorretal antes e após a cirurgia. De acordo com os dados do ultrassom, pacientes do sexo masculino com envolvimento ≥50% do esfíncter externo anterior ou esfíncter externo+puborretal e do sexo feminino com envolvimento ≥40% foram referidos para cirurgia de ligadura do trajeto no espaço inter-esfinctérico (LIFT) ou colocação do sedenho. Aqueles com envolvimento <50% em homens e <40% mulheres foram indicados para fistulotomia em um tempo. Após a cirurgia, a musculatura secccionada (fibrose) e o músculo residual foram medidos e comparados no pós-operatório. RESULTADOS: Um total de 73 pacientes foi incluído. A indicação para LIFT foi significativamente maior em mulheres (47%) e a fistulotomia em homens (46%) e o sedenho similar em ambos os sexos. Sintomas de incontinência leve foi identificado em 31% dos submetidos à cirurgia com divisão de esfíncter e similar em ambos os sexos. O ultrassom identificou sete casos que não cicatrizaram. CONCLUSÃO: O ultrassom anorretal tridimensional demonstrou ser um método efetivo na avaliação da fístula anal, quantificando o comprimento do esfíncter a ser dividido, como demonstrado no resultado pós-operatório, fornecendo um tratamento seguro de acordo com sexo e percentual de músculo envolvido. Adicionalmente, identifica o tecido cicatrizado, tipo de recorrência e a falha no tratamento.

CAN THREE-DIMENSIONAL ANORECTAL ULTRASONOGRAPHY BE INCLUDED AS A DIAGNOSTIC TOOL FOR THE ASSESSMENT OF ANAL FISTULA BEFORE AND AFTER SURGICAL TREATMENT?

BACKGROUND: There is no a clear knowledge concerning the division of any part of the anal sphincter complex and the effect of this procedure on the function of the anal canal during the treatment of perianal fistula. OBJECTIVE: To evaluate the usefulness of 3D anorectal ultrasound in the assessment of anal fistula, quantifying the length of the sphincter muscle to be transected, selecting patients for different approaches and identifying healing, failure or recurrence after the surgical treatment. METHODS: A prospective study included patients with primarily cryptogenic transsphincteric anal fistula assessed by fecal Incontinence score, tri-dimensional anorectal ultrasound and anal manometry before and after surgery. Based on 3D-AUS, patients with ≥50% external sphincter or external sphincter+puborectalis muscle involvement in males and ≥40% external sphincter or external sphincter+puborectalis muscle in females were referred for the ligation of the intersphincteric tract (LIFT) or seton placement and subsequent fistulotomy; and with <50% involvement in males and <40% in females were referred to one-stage fistulotomy. After surgery, the fibrosis (muscles divided) and residual muscles were measured and compared with the pre-operative. RESULTS: A total of 73 patients was included. The indication for the LIFT was significantly higher in females (47%), one-stage fistulotomy was significantly higher in the males (46%) and similar in seton placement. The minor postoperative incontinence was identified in 31% of patients underwent sphincter divided and were similar in both genders. The 3D-AUS identified seven failed cases. CONCLUSION: The 3D ultrasound was shown to be an effective method in the preoperative assessment of anal fistulas by quantifying the length of muscle to be divided, as the results were similar at the post-operative, providing a safe treatment approach according to the gender and percentage of muscle involvement. Additionally, 3D ultrasound successfully identified the healing tissue and the type of failure or recurrence.

Ponderal behavior of rats fed an omegas 3, 6 and 9 enriched diet submitted to colon carcinogenesis induced by azoxymethane.

PURPOSE: To assess weight changes in rats fed diets with different ratios of omegas 3, 6 and 9 submitted to colonic carcinogenesis induced by Azoxymethane (AOM). METHODS: Sixty rats with three weeks of life were distributed into five groups of specific diets containing 12 animals each: GI- Standard diet without administration of AOM, GII- Standard diet with administration of AOM; GIII- Hyperlipidic diet with administration of AOM; GIV-Normolipidic diet with administration of AOM; GV- Hypolipidic diet with administration of AOM. The weight and food intake of each group were assessed four times in each week throughout the experiment until euthanasia at 36th week. RESULTS: GI and GII had no significant difference in weight. GI showed a significant increase when compared to GIII, GIV and GV. GII also showed a significant increase when compared to GIII, GIV and GV. When comparing intake of GI as compared to GII no significant difference was found, however such groups had higher intake than groups III, IV and V. There were found no difference in weight when comparing among rats with and without cancer within each groups: GII, GIII, GIV and GV. CONCLUSIONS: Diets rich in omega 3, 6 and 9 reduced food intake and weight. Rats with colorectal cancer had no decrease in weight as compared to those without this condition in the same group.

Ponderal behavior of rats fed an omegas 3, 6 and 9 enriched diet submitted to colon carcinogenesis induced by azoxymethane

PURPOSE: To assess weight changes in rats fed diets with different ratios of omegas 3, 6 and 9 submitted to colonic carcinogenesis induced by Azoxymethane (AOM). METHODS: Sixty rats with three weeks of life were distributed into five groups of specific diets containing 12 animals each: GI- Standard diet without adminstration of AOM, GII- Standard diet with adminstration of AOM; GIII- Hyperlipidic diet with adminstration of AOM; GIV-Normolipidic diet with adminstration of AOM; GV- Hypolipidic diet with adminstration of AOM. The weight and food intake of each group were assessed four times in each week throughout the experiment until euthanasia at 36th week. RESULTS: GI and GII had no significant difference in weight. GI showed a significant increase when compared to GIII, GIV and GV. GII also showed a significant increase when compared to GIII, GIV and GV. When comparing intake of GI as compared to GII no significant difference was found, however such groups had higher intake than groups III, IV and V. There were found no difference in weight when comparing amoung rats with and without cancer within each groups: GII, GIII, GIV and GV. CONCLUSIONS: Diets rich in omega 3, 6 and 9 reduced food intake and weight. Rats with colorectal cancer had no decrease in weight as compared to those without this condition in the same group.

Hepatic repercussions of azoxymethane-induced colorectal carcinogenesis.

OBJECTIVE: To evaluate the hepatic effects of colonic carcinogenesis induced by azoxymethane at different doses and times of exposure in rats. METHODS: Forty-four Wistar rats were divided into four groups. The animals were eight weeks at the beginning of the experiment. group 1 received 1.0 ml of saline intraperitoneally once a week for two weeks. Group 2 received 15 mg/kg of azoxymethane intraperitoneally once a week for two weeks. These animals were killed at the 15th week of the experiment. The animals of group 3 received saline intraperitoneally once a week for two weeks. Group 4 animals received 20mg/kg of azoxymethane intraperitoneally once a week for two weeks. These animals were killed at the 26th week of the experiment. The fragments of liver tissue were stained with hematoxylin and eosin and evaluated microscopically. RESULTS: Groups 1 and 2 differed significantly in relation to steatosis, no difference having been found between group 3 and group 4. However, in group 4 we observed pre-neoplastic lesions (foci of altered, clear, vacuolated, basophilic, amphophilic tigroid, oncocytic, small or acidophilus cells, spongiosis and peliosis) and neoplastic lesions (adenomas and colangiomas) containing atypical hepatocytes in between, not identified in group 3. CONCLUSION: In the model of colorectal carcinogenesis, preneoplastic and neoplastic hepatic lesions appear and evolve in proportion to the time of exposure and dose of azoxymethane.

Repercussão hepática da carcinogênese colorretal induzida pelo azoximetano / Hepatic repercussions of azoxymethane-induced colorectal carcinogenesis

OBJETIVO: Avaliar as repercussões hepáticas da carcinogênese colônica induzida por diferentes doses e tempos de exposição ao azoximetano em ratos Wistar. MÉTODOS: Quarenta e quatro ratos foram distribuídos em quatro grupos. Os animais tinham oito semanas no início do experimento. No grupo 1, receberam 1.0mL de solução salina intraperitonealmente uma vez por semana por duas semanas. No grupo 2, receberam 15 mg/kg de azoximetano intraperitonealmente uma vez por semana por duas semanas. Esses animais foram mortos na 15ª semana do experimento. Os animais do grupo 3 receberam solução salina intraperitonealmente uma vez por semana por duas semanas. Os animais do grupo 4 receberam 20mg/kg de azoximetano intraperitonealmente uma vez por semana por duas semanas. Esses animais foram mortos na 26ª semana do experimento. Os fragmentos de tecido hepático foram corados pela hematoxilina e eosina e avaliadas microscopicamente. RESULTADOS: Grupo 1 e grupo 2 diferiram significantemente em relação a esteatose, mas não houve diferença entre o grupo 3 e o grupo 4. No entanto, no grupo 4 foram observadas lesões pré-neoplásicas (focos de células alteradas, claras, vacuoladas, basofílicas, anfofílicas, tigróides, oncocíticas, pequenas ou acidófilas, espongioses e pelioses) e lesões neoplásicas (colangiomas e adenomas) contendo hepatócitos atípicos de permeio, não identificados no grupo 3. CONCLUSÃO: No modelo de carcinogênese colorretal, lesões hepáticas pré-neoplásicas e neoplásicas aparecem e evoluem na proporção do tempo e dose de exposição ao azoximetano.

OBJECTIVE: To evaluate the hepatic effects of colonic carcinogenesis induced by azoxymethane at different doses and times of exposure in rats. METHODS: Forty-four Wistar rats were divided into four groups. The animals were eight weeks at the beginning of the experiment. group 1 received 1.0ml of saline intraperitoneally once a week for two weeks. Group 2 received 15 mg/kg of azoxymethane intraperitoneally once a week for two weeks. These animals were killed at the 15th week of the experiment. The animals of group 3 received saline intraperitoneally once a week for two weeks. Group 4 animals received 20mg/kg of azoxymethane intraperitoneally once a week for two weeks. These animals were killed at the 26th week of the experiment. The fragments of liver tissue were stained with hematoxylin and eosin and evaluated microscopically. RESULTS: Groups 1 and 2 differed significantly in relation to steatosis, no difference having been found between group 3 and group 4. However, in group 4 we observed pre-neoplastic lesions (foci of altered, clear, vacuolated, basophilic, amphophilic tigroid, oncocytic, small or acidophilus cells, spongiosis and peliosis) and neoplastic lesions (adenomas and colangiomas) containing atypical hepatocytes in between, not identified in group 3. CONCLUSION: In the model of colorectal carcinogenesis, preneoplastic and neoplastic hepatic lesions appear and evolve in proportion to the time of exposure and dose of azoxymethane.

Effect of a hyperlipidic diet rich in omegas 3, 6 and 9 on aberrant crypt formation in rat colonic mucosa / Efeito de uma dieta hiperlipídica rica em ômegas 3, 6 e 9 na formação de criptas aberrantes em mucosa cólica de ratos

PURPOSE: To determine whether a hypercaloric and hyperlipidic diet enriched with polyunsaturated fatty acids influences the formation of aberrant crypt foci (ACF) in colonic mucosa of Wistar rats treated with azoxymethane (AOM). METHODS: At eight weeks of life, the rats were assigned to four groups: Group I―standard diet (STD) not treated with AOM; Group II―hypercaloric and hyperlipidic diet (FED), not treated with AOM; Group III―STD, treated with AOM; Group IV―FED, treated with AOM. At 16 weeks, the animals were injected intraperitoneal with 0.9 percent saline solution (Group I and II) or AOM at 15mg/Kg (Groups III and IV) once a week for two weeks. Fifteen weeks later, the animals were euthanized. RESULTS: FED promoted weight gain in Groups II and IV compared to Groups I and III, respectively. The groups did not differ with regard to the total number of ACF. The Chi-square test revealed no predominance of the presence of foci with <4 crypts. However, foci with ≥5 crypts were proportionally more prevalent in Group III than in Group IV (p=0.043). CONCLUSION: The administration of polyunsaturated fatty acids did not interfere with the formation of aberrant crypt foci, but reduced ACF multiplicity, exercising an attenuating effect on carcinogenesis.

OBJETIVO: Determinar se uma dieta hipercalórica, hiperlipídica, rica em ácidos graxos poliinsaturados (FED) tem influência na formação de focos de cripta aberrante (FCA) em mucosa cólica de ratos Wistar expostos ao azoximetano (AOM). MÉTODOS: Com oito semanas de vida, os ratos foram distribuídos em quatro grupos: Grupo I: Dieta padrão (SD) sem AOM; Grupo II: FED, sem AOM; Grupo III: SD, com AOM; Grupo IV: FED com AOM. Com 16 semanas, os animais dos grupos I e II receberam injeções intraperitoneais de solução salina 0,9 por cento, enquanto os dos grupos III e IV receberam AOM na dose de 15mg/Kg de peso, 1 vez por semana por duas semanas. Quinze semanas após, os animais foram mortos. RESULTADOS: FED promoveu aumento de peso nos grupos II e IV em relação aos grupos I e III. Não houve aumento significante no número total de FCA entre os grupos. Em relação à multiplicidade das criptas por FCA, o teste do qui-quadrado mostrou que não houve predominância da presença <4 criptas por foco. Contudo, focos ≥5 criptas foram proporcionalmente mais prevalentes no grupo III que no grupo IV (p=0,043). CONCLUSÃO: Os ácidos graxos poliinsaturados não interferem na formação de focos de cripta aberrante, contudo reduz sua multiplicidade, exercendo efeito atenuador na carcinogênese.

Effect of a hyperlipidic diet rich in omegas 3, 6 and 9 on aberrant crypt formation in rat colonic mucosa.

PURPOSE: To determine whether a hypercaloric and hyperlipidic diet enriched with polyunsaturated fatty acids influences the formation of aberrant crypt foci (ACF) in colonic mucosa of Wistar rats treated with azoxymethane (AOM). METHODS: At eight weeks of life, the rats were assigned to four groups: Group I-standard diet (STD) not treated with AOM; Group II-hypercaloric and hyperlipidic diet (FED), not treated with AOM; Group III-STD, treated with AOM; Group IV-FED, treated with AOM. At 16 weeks, the animals were injected intraperitoneal with 0.9% saline solution (Group I and II) or AOM at 15 mg/Kg (Groups III and IV) once a week for two weeks. Fifteen weeks later, the animals were euthanized. RESULTS: FED promoted weight gain in Groups II and IV compared to Groups I and III, respectively. The groups did not differ with regard to the total number of ACF. The Chi-square test revealed no predominance of the presence of foci with <4 crypts. However, foci with ≥5 crypts were proportionally more prevalent in Group III than in Group IV (p=0.043). CONCLUSION: The administration of polyunsaturated fatty acids did not interfere with the formation of aberrant crypt foci, but reduced ACF multiplicity, exercising an attenuating effect on carcinogenesis.

Optimization of visibility and quantification of aberrant crypt foci in colonic mucosa in Wistar rats / Otimização da visibilidade e quantificação de focos de criptas aberrantes em mucosa cólica de ratos Wistar

Purpose: Test immersion of microscopy samples in water as an aid to visualizing and quantifying aberrant crypt foci (ACF) in rat colon mucosa. Methods: Carcinogenesis was induced with azoxymethane in Wistar rats kept on a conventional diet or a hypercaloric diet containing unsaturated fat. Fifteen weeks after induction, colon samples were retrieved and fixated in a 10 percent formaldehyde solution. The samples were divided into segments (distal, middle, proximal) and stained with 1 percent toluidine blue. The technique tested in the study consisted of immersing microscopy samples in distilled water in order to eliminate the problem of light reflection known from conventional microscopy. Results: When samples were immersed in water during microscopy, significantly more ACF could be visualized in all colon segments than with the conventional method proposed by Bird. Conclusion: Immersing microscopy samples in water aids the visualization and quantification of aberrant crypt foci in rat colon mucosa fixed in formaldehyde.

Objetivo: Otimizar a visibilização de focos de criptas aberrantes (FCA) em mucosa cólica de ratos Wistar. Métodos: Colo de rato Wistar, sob diferentes dietas e submetidos a iniciação de carcinogênese pelo azoximetano há 4 meses, foram previamente lavados, abertos e fixados em solução de formalina a 10 por cento por 24 horas. Após serem corados em azul de toluidina a 1 por cento, foram divididos em segmentos distal, médio e proximal e imersos em água destilada para quantificação de FCA. Resultados: No método de imersão foi visibilizado maior quantidade de focos de criptas aberrantes em todos os segmentos cólicos, com diferença significante, quando comparado com o método de Bird. Conclusão: O método de imersão otimiza a visibilização e quantificação de focos de criptas aberrantes em mucosa cólica (ratos Wistar) fixada em solução de formalina a 10 por cento.

Optimization of visibility and quantification of aberrant crypt foci in colonic mucosa in Wistar rats.

PURPOSE: Test immersion of microscopy samples in water as an aid to visualizing and quantifying aberrant crypt foci (ACF) in rat colon mucosa. METHODS: Carcinogenesis was induced with azoxymethane in Wistar rats kept on a conventional diet or a hypercaloric diet containing unsaturated fat. Fifteen weeks after induction, colon samples were retrieved and fixated in a 10% formaldehyde solution. The samples were divided into segments (distal, middle, proximal) and stained with 1% toluidine blue. The technique tested in the study consisted of immersing microscopy samples in distilled water in order to eliminate the problem of light reflection known from conventional microscopy. RESULTS: When samples were immersed in water during microscopy, significantly more ACF could be visualized in all colon segments than with the conventional method proposed by Bird. CONCLUSION: Immersing microscopy samples in water aids the visualization and quantification of aberrant crypt foci in rat colon mucosa fixed in formaldehyde.