Modulação da cicatrização na cirurgia do glaucoma após aplicação de acetato de triancinolona subconjuntival isolado ou em associação à mitomicina C: estudo experimental / Healing modulation in glaucoma surgery after application of subconjunctival triamcinolone acetate alone or combined with mitomycin C: an experimetal study

RESUMO Objetivo: estudar a eficácia e segurança do uso de acetato de triancinolona subconjuntival isolado ou em associação à mitomicina C como modulador da cicatrização de trabeculectomias em coelhos. Métodos: trinta coelhos machos, albinos, raça Nova Zelândia foram submetidos à trabeculectomia bilateralmente. Os animais foram divididos em quatro grupos experimentais com 15 olhos por grupo: controle, mitomicina C, acetato de triancinolona e acetato de triancinolona + mitomicina C. Tonometria de aplanação e análise clínica da bolha através do Sistema de Graduação de Moorfields foram obtidas no pós-operatório. Para a avaliação da cicatrização, procedeu-se à análise quantitativa do infiltrado inflamatório (polimorfonucleares) através da coloração Hematoxilina & Eosina e da proliferação vascular por imuno-histoquímica. Resultados: foi observada em todos os grupos diminuição significativa da pressão intraocular pós-operatória em relação à pré-operatória (p<0,001). Contudo, não houve diferença entre os grupos (p=0,186). O grupo acetato de triancinolona + mitomicina C apresentou melhores índices na altura máxima da bolha e na vascularização da área central da bolha (p=0,001); além disso, houve menor resposta inflamatória (p=0,001) e menor proliferação vascular (p=0,001) na fase intermediária do estudo em relação às monoterapias. Conclusão: a associação da mitomicina C ao acetato de triancinolona resultou numa ação sinérgica entre esses agentes, com bolhas mais amplas e difusas e menor infiltrado inflamatório e menor proliferação vascular em estágio intermediário do acompanhamento neste modelo animal.

ABSTRACT Objective: to study the efficacy and safety of the use of subconjunctival triamcinolone acetate alone or in combination with mitomycin C as a modulator of trabeculectomy healing in rabbits. Methods: we submitted thirty male, albino, New Zealand rabbits to bilateral trabeculectomy. We divided the animals into four experimental groups with 15 eyes per group: control, mitomycin C, triamcinolone acetate and triamcinolone acetate + mitomycin C. We performed aplanation tonometry and clinical analysis of the bleb through the Moorfields Graduation System in the postoperative period. For the evaluation of healing, we carried out the quantitative analysis of the inflammatory infiltrate (polymorphonuclear) through Hematoxylin & Eosin staining, and vascular proliferation, through immunohistochemistry. Results: we observed a significant decrease in postoperative intraocular pressure in all groups compared with the preoperative pressure (p<0.001). However, there was no difference between groups (p=0.186). The triamcinolone + mitomycin C acetate group presented better indices as for the maximum bleb height and vascularization of the bleb central area (p=0.001); in addition, there was a lower inflammatory response (p=0.001) and lower vascular proliferation (p=0.001) in the intermediate phase of the study compared with the monotherapies. Conclusion: the combination of mitomycin C and triamcinolone acetate resulted in a synergistic action between these agents, with broader and more diffuse blebs, less inflammatory infiltrate and less vascular proliferation in the intermediate stages of follow-up in this animal model.

Natural products as new antimitotic compounds for anticancer drug development

Cell cycle control genes are frequently mutated in cancer cells, which usually display higher rates of proliferation than normal cells. Dysregulated mitosis leads to genomic instability, which contributes to tumor progression and aggressiveness. Many drugs that disrupt mitosis have been studied because they induce cell cycle arrest and tumor cell death. These antitumor compounds are referred to as antimitotics. Vinca alkaloids and taxanes are natural products that target microtubules and inhibit mitosis, and their derivatives are among the most commonly used drugs in cancer therapy worldwide. However, severe adverse effects such as neuropathies are frequently observed during treatment with microtubule-targeting agents. Many efforts have been directed at developing improved antimitotics with increased specificity and decreased likelihood of inducing side effects. These new drugs generally target specific components of mitotic regulation that are mainly or exclusively expressed during cell division, such as kinases, motor proteins and multiprotein complexes. Such small molecules are now in preclinical studies and clinical trials, and many are products or derivatives from natural sources. In this review, we focused on the most promising targets for the development of antimitotics and discussed the advantages and disadvantages of these targets. We also highlighted the novel natural antimitotic agents under investigation by our research group, including combretastatins, withanolides and pterocarpans, which show the potential to circumvent the main issues in antimitotic therapy.

Carcinoma espinocelular de conjuntiva com evolução para exenteração: relato de caso / Conjunctival squamous cell carcinoma requiring orbital exenteration: case report

Portador de carcinoma espinocelular da conjuntiva teve a lesão removida, com recorrência em outra localização. O paciente recebeu ciclos de 5-Fluoruracila como tratamento adjuvante à remoção cirúrgica, apresentando evolução desfavorável que chegou à exenteração orbitária. São feitos comentários quanto ao uso de antimitóticos no tratamento destas lesões.

A case of a squamous cell carcinoma of the conjunctiva is presented. The lesion was removed with recurrence in another conjunctival site. The patient received cycles of 5-Fluorouracil as adjuvant treatment to the surgical removal and presented unfavorable evolution, requiring orbital exenteration. Comments are made on the use of antimitotic drugs in the management of these lesions.

Arsenic trioxide induces depolymerization of microtubules in an acute promyelocytic leukemia cell line

BACKGROUND: Arsenic trioxide (As2O3) is a well-known and effective treatment that can result in clinical remission for patients diagnosed with acute promyelocytic leukemia (APL). The biologic efficacy of As2O3 in APL and solid tumor cells has been explained through its actions on anti-proliferation, anti-angiogenesis, and apoptotic signaling pathways. We theorize that As2O3 activates a pathway that disrupts microtubule dynamics forming abnormal, nonfunctioning mitotic spindles, thus preventing cellular division. In this study, we investigated how As2O3 induces apoptosis by causing microtubule dysfunction. METHODS: Cultured NB4 cells were treated with As2O3, paclitaxel, and vincristine. Flow cytometric analysis was then performed. An MTT assay was used to determine drug-mediated cytotoxicity. For tubulin polymerization assay, each polymerized or soluble tubulin was measured. Microtubule assembly-disassembly was measured using a tubulin polymerization kit. Cellular microtubules were also observed with fluorescence microscopy. RESULTS: As2O3 treatment disrupted tubulin assembly resulting in dysfunctional microtubules that cause death in APL cells. As2O3 markedly enhanced the amount of depolymerized microtubules. The number of microtubule posttranslational modifications on an individual tubulin decreased with As2O3 concentration. Immunocytochemistry revealed changes in the cellular microtubule network and formation of polymerized microtubules in As2O3-treated cells. CONCLUSION: The microtubules alterations found with As2O3 treatment suggest that As2O3 increases the depolymerized forms of tubulin in cells and that this is potentially due to arsenite's negative effects on spindle dynamics.

Segurança e efetividade no tratamento do pterígio usando infiltração de 5-fluoruracila no intraoperatório / Safety and efficacy of intraoperative 5-fluorouracil infiltration in pterygium treatment

Objetivo: Avaliar a segurança e a efetividade do uso do 5-fluoruracila(5-FU) como tratamento adjuvante do pterígio, aplicado sob a forma de infiltração subconjuntival, no período intraoperatório. Métodos: Foram avaliados prospectivamente 125 indivíduos (125 olhos) portadores depterígio. Os indivíduos foram operados segundo a técnica de retalho de deslizamento e receberam, ao final do procedimento, injeção subconjuntivalde 0,2 mL de 5-FU (25 mg/mL). Foram anotados os dados do paciente como idade, sexo, profissão, características da lesão (primário ou recidivado, tamanho, carnoso ou involutivo) e feito seguimento pósoperatório, aos 7, 21, 60 e 180 dias. Os dados foram submetidos àavaliação estatística. Resultados: Não foram observados casos de complicaçãodecorrente do uso do 5-FU em injeção no intraoperatório do pterígio. A taxa de recidiva geral observada aos 180 dias de pós-operatório foi de 35,8%, sendo de 35,7% para os pterígios primários e de 36,4% para os recidivados. Conclusão: A aplicação do 5-FU no período intraoperatório sob a forma de infiltração subconjuntival é segura. Entretanto, ainda resulta em altas taxas de recidiva e novos estudos devem serrealizados a fim de conhecer a concentração/dose ideal que permitirámenores chances de recidiva da lesão.

Purpose: To investigate the safety and efficacy of intraoperative infiltration of 5-fluorouracil (5-FU) as an adjuvant drug in pterygium treatment. Methods: Of 125 consecutive patients, 125 eyes with primary and recurrent pterygium underwent pterygium excision with intraoperative 5-FU (25 mg/mL) infiltration. The superior and inferior conjunctiva was approximated to cover the scleral bed and 0.2 mL 5-FU wasinjected at the end of the surgical procedure. The gender, occupation, pterygium characteristics and the follow-up at 7, 21, 60 e 180 days after surgery were evaluated and the data were statistically analyzed. Results: With follow-up of 180 days the patients had no serious complications observed duringor after surgery. The relapse rate was 35.8% and occurred in primary (35.7%) and recurrent (36.4%) lesions with no statistical difference. Conclusions: This study suggests that intraoperative infiltration of 5-FU is safe. However the high recurrence rate indicated that other studies would be necessary to show the concentration/dose to better prevent it.

Exposição de fibroblastos da cápsula de Tenon normal de portadores de pterígio ao 5-fluorouracil e à mitomicina C / Exposure of normal Tenon's capsule fibroblasts from pterygium to 5-fluorouracil and mitomycin C

OBJETIVO: Avaliar a atividade proliferativa dos fibroblastos da cápsula de Tenon normal, proveniente de portadores de pterígios primários e recidivados. MÉTODOS: Foi realizado estudo prospectivo, aleatório, avaliando-se fragmentos da cápsula de Tenon normal, removidos de 20 portadores de pterígios primários e 21, recidivados. A taxa de proliferação foi avaliada em fibroblastos de terceira passagem, quando as culturas foram expostas a agentes antimitóticos: mitomicina C e 5-fluorouracil. Os dados obtidos foram submetidos à análise estatística. RESULTADOS: Dentre os 41 espécimes cultivados, apenas 1 de pterígio primário e 2 de recidivado proliferaram. Quando expostos a mitomicina C e ao 5-fluorouracil não houve diferença estatisticamente significativa quanto a inibição de proliferação celular. CONCLUSÃO: Desta forma, in vitro, ambos os antimitóticos estudados têm a mesma eficácia na inibição da proliferação sobre os fibroblastos de cápsulas de Tenon normal.

PURPOSE: To evaluate the fibroblast proliferation activity of normal Tenon's capsule from primary and recurrent patients with pterygium. METHODS: A randomized prospective study was performed with 41 normal Tenon's capsule fragments from 21 primary and 20 recurrent patients with pterygium. The sample was collected from the inferior cul-de-sac. Proliferation rate from fibroblasts were evaluated after mitomycin C and 5-fluorouracil exposition. Data were submitted to statistical analysis. RESULTS: Of the 41 cultivated normal Tenon's capsules, only 1 from primary and 2 from recurrent pterygium patients proliferated. After antimitotic exposition, the proliferation rate was similar with both drugs. CONCLUSION: Mitomycin and 5-fluorouracil promote similar inhibition regarding proliferation of normal Tenon's fibroblast cultures.