Efeito da mitomicina c no epitélio ciliar estudo experimental em coelhos com microscopia eletrônica de varredura e de transmissão

Purpose: To evaluate and correlate in the rabbit the possible changes caused by mitomycin C under the scleral flap in the ciliary epithelium with transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Methods: The eyes of 32 albino rabbits were studied and divided in 4 experimental groups. The right eye (RE) was intended for the experimental groups and the left eye (LE) for the controls. Group I (G1) was formed by 8 eyes that received 0,5 mg/ml of mitomycin C under the scleral flap and were examined after 15 days. Group II (G2) differed from G1 only in the time of the exam, after 30 days. Group III (G3) was formed by 8 eyes that received 0,2 mg/ml of mitomycin C under the scleral flap and were examined after 15 days. Group IV (G4) differed from group 3 just in the time of the exam, after 30 days. In each eye the internal ciliary epithelium were examined with TEM. Results: The following changes in the internal ciliary epithelium were observed in groups G2, G3, and G4 with TEM: discontinuous and irregular basement membrane, more irregular and electron-dense nucleous, enlargement among interdigitation, edematous mitochondria and myelin figures. These alterations were not found in all the animals of the groups. Group G 1 did not present alterations. Roughness in groups G 1, G2, G3 and G4 were observed with SEM. In groups G 1 and G2 continuity solutions were also observed. Conclusion: Mitomycin C in 0,2 mg/ml and 0,5 mg/ml concentrations caused changes in the internal ciliary epithelium 15 and 30 days after, with TEM and SEM. There was no correlation between dosage, time and with TEM and SEM.

Exposição de culturas de fibroblastos de pterígios primários e recidivados à mitomicina c e ao 5-fluorouracil

Purpose: To evaluate the proliferation of the fibroblasts from primary and recurrent pterygium in culture of cells, after the exposure to mitomycin C and to 5-fluorouracil. Methods: Cultures of fibroblasts from primary and recurrent pterygiuns had been carried through. The cells of the third passage were exposed to mitomycin C 0.4% during 3 minutes and to 5-fluorouracil 25mg/ml that was kept in the nutritional medium. After 3, 6, 12 and 18 days of the exposure, cell countings were made in hemocytometer, in triplicate, with a control not treated with the drugs for each day. The data were submitted to statistical analysis.Results: Mitomicyn C had homogeneous behavior in the primary and recurrent groups, which inhibited the cellular proliferation since the first counting day. However, with 5-fluorouracil, the proliferation inhibition was verified only after the third day of evaluation (in the second counting day) in the recurrent group, and since the first counting day in the primary group. At the end of the experimental period, 5-fluorouracil and mitomycin C were equally efficient in the inhibition of the fibroblasts from primary and recurrent pterygium proliferation. In the controls not exposed, the cell's numbers were increasing during the experimental time.Conclusion: Mitomycin and 5-fluorouracil are equally able to inhibit fibroblasts proliferation from primary and recurrent pterygium Tenon's capsule in cell culture.

Análise histopatológica e ultraestrutural do esôfago distal de ratos com lesão cáustica submetidos à aplicação tópica de mitomicina C

Pós-graduação em Bases Gerais da Cirurgia - FMB

Emprego da mitomicina C como agente antifibrótico na mioplastia do reto medial do bulbo do olho de coelhos (Oryctolagus cuniculus, Linnaeus, 1758) pela cápsula renal de eqüino ( Equus caballus, 1758)

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

Efeitos da administração tópica per-operatória da mitomicina C, em diferentes concentrações, sobre a cicatrização de mioplastias do reto dorsal do bulbo do olho de coelhos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Comparative Studies of the (Anti) Mutagenicity of Baccharis dracunculifolia and Artepillin C by the Bacterial Reverse Mutation Test

Baccharis dracunculifolia is a plant native from Brazil, commonly known as 'Alecrim-do-campo' and 'Vassoura' and used in alternative medicine for the treatment of inflammation, hepatic disorders and stomach ulcers. Previous studies reported that artepillin C (ArtC, 3-{4-hydroxy-3,5-di(3-methyl-2-butenyl)phenyl}-2(E)-propenoic acid), is the main compound of interest in the leaves. This study was undertaken to assess the mutagenic effect of the ethyl acetate extract of B. dracunculifolia leaves (Bd-EAE: 11.4-182.8 mu g/plate) and ArtC (0.69-10.99 mu g/plate) by the Ames test using Salmonella typhimurium strains TA98, TA97a, TA100 and TA102, and to compare the protective effects of Bd-EAE and ArtC against the mutagenicity of a variety of direct and indirect acting mutagens such as 4-nitro-O-phenylenediamine, sodium azide, mitomycin C, benzo[a]pyrene, aflatoxin B1, 2-aminoanthracene and 2-aminofluorene. The mutagenicity test showed that Bd-EAE and ArtC did not induce an increase in the number of revertant colonies indicating absence of mutagenic activity. ArtC showed a similar antimutagenic effect to that of Bd-EAE in some strains of S. typhimurium, demonstrating that the antimutagenic activity of Bd-EAE can be partially attributed to ArtC. The present results showed that the protective effect of whole plant extracts is due to the combined and synergistic effects of a complex mixture of phytochemicals, the total activity of which may result in health benefits.

A tumour-derived mutant allele of XRCC2 preferentially suppresses homologous recombination at DNA replication forks

Homologous recombination repair (HRR) is required for both the repair of DNA double strand breaks (DSBs) and the maintenance of the integrity of DNA replication forks. To determine the effect of a mutant allele of the RAD51 paralog XRCC2 (342delT) found in an HRR-defective tumour cell line, 342delT was introduced into HRR proficient cells containing a recombination reporter substrate. In one set of transfectants, expression of 342delT conferred sensitivity to thymidine and mitomycin C and suppressed HRR induced at the recombination reporter by thymidine but not by DSBs. In a second set of transfectants, the expression of 342delT was accompanied by a decreased level of the full-length XRCC2. These cells were defective in the induction of HRR by either thymidine or DSBs. Thus 342delT suppresses recombination induced by thymidine in a dominant negative manner while recombination induced by DSBs appears to depend upon the level of XRCC2 as well as the expression of the mutant XRCC2 allele. These results suggest that HRR pathways responding to stalled replication forks or DSBs are genetically distinguishable. They further suggest a critical role for XRCC2 in HRR at replication forks, possibly in the loading of RAD51 onto gapped DNA.

Response to chemotherapy is predictive in relation to longer overall survival in an individual patient combined-analysis with pleural mesothelioma

Background: There is currently no early predictive marker of survival for patients receiving chemotherapy for malignant pleural mesothelioma (MPM). Tumour response may be predictive for overall survival (OS), though this has not been explored. We have thus undertaken a combined-analysis of OS, from a 42 day landmark, of 526 patients receiving systemic therapy for MPM. We also validate published progression-free survival rates (PFSRs) and a progression-free survival (PFS) prognostic-index model. Methods: Analyses included nine MPM clinical trials incorporating six European Organisation for Research and Treatment of Cancer (EORTC) studies. Analysis of OS from landmark (from day 42 post-treatment) was considered regarding tumour response. PFSR analysis data included six non-EORTC MPM clinical trials. Prognostic index validation was performed on one non-EORTC data-set, with available survival data. Results: Median OS, from landmark, of patients with partial response (PR) was 12·8 months, stable disease (SD), 9·4 months and progressive disease (PD), 3·4 months. Both PR and SD were associated with longer OS from landmark compared with disease progression (both p < 0·0001). PFSRs for platinum-based combination therapies were consistent with published significant clinical activity ranges. Effective separation between PFS and OS curves provided a validation of the EORTC prognostic model, based on histology, stage and performance status. Conclusion: Response to chemotherapy is associated with significantly longer OS from landmark in patients with MPM. © 2012 Elsevier Ltd. All rights reserved.

Bone matters in lung cancer

Background: Bone metastases are a significant and undertreated clinical problem in patients with advanced lung cancer. Design: We reviewed the incidence of bone metastases and skeletal-related events (SREs) in patients with lung cancer and examined the burden on patients' lives and on health care systems. Available therapies to improve survival and lessen the impact of SREs on quality of life (QoL) were also investigated. Results: Bone metastases are common in lung cancer; however, owing to short survival times, data on the incidences of SREs are limited. As with other cancers, the costs associated with treating SREs in lung cancer are substantial. Bisphosphonates reduce the frequency of SREs and improve measures of pain and QoL in patients with lung cancer; however, nephrotoxicity is a common complication of therapy. Denosumab, a recently approved bone-targeted therapy, is superior to zoledronic acid in increasing the time to first on-study SRE in patients with solid tumours, including lung cancer. Additional roles of bone-targeted therapies beyond the prevention of SREs are under investigation. Conclusions: With increasing awareness of the consequences of SREs, bone-targeted therapies may play a greater role in the management of patients with lung cancer, with the aim of delaying disease progression and preserving QoL. © The Author 2012. Published by Oxford University Press on behalf of the European Society for Medical Oncology.

Platinum-based chemotherapy in metastatic breast cancer : current status

Cisplatin and carboplatin are active in previously untreated patients with metastatic breast cancer (MBC) with mean response rates (RRs) of 50 and 32%, respectively. In pretreated patients the RR to cisplatin/carboplatin monotherapy declines markedly to <10%. Cisplatin and carboplatin have been combined with many other cytotoxics. In first-line setting high activity has been observed in combination with taxanes or vinorelbine (RRs consistently ∼60%). It appears that these newer combinations are superior to older regimens with etoposide (RRs 30 to 50%) or 5-fluorouracil (RRs 40 to 60%). Cisplatin-/carboplatin-based regimens with infusional 5-FU and epirubicin/paclitaxel/vinorelbine achieve high RRs of around 60 to 80%. However these regimens are difficult to administer in all patients because they require central venous access for continuous 5-FU infusion. In pretreated MBC the combinations of cisplatin-taxane/vinorelbine/gemcitabine or carboplatin-docetaxel/vinorelbine yield RRs of 40 to 50%, which are higher than those achieved with platinum-etoposide/5-FU. In locally advanced disease cisplatin-based regimens achieve very high RRs (>80%). This would suggest that in chemotherapy-naïve patients platinum-based therapy might have an important role to play. Additionally the synergy demonstrated between platinum compounds, taxanes and herceptin, in preclinical and clinical studies is of immense importance and the results of the two ongoing Breast Cancer International Research Group randomized phase III studies are eagerly awaited. These studies may help clarify the role of platinum compounds in the treatment of metastatic and possibly early breast cancer. © 2003 Elsevier Ltd. All rights reserved.

Platinum-based chemotherapy in metastatic breast cancer : the Leicester (UK) experience

Aims: After failure of anthracycline- and taxane-based chemotherapy in metastatic breast cancer, treatment options until recently were limited. Until the introduction of capecitabine and vinorelbine, no standard regimen was available. We conducted a retrospective study to determine the efficacy and toxicity of platinum-based chemotherapy in metastatic breast cancer. Materials and methods: Forty-two women with metastatic breast cancer previously treated with anthracyclines (93%) and/or taxanes (36%) received mitomycin-vinblastine-cisplatin (MVP) (n = 23), or cisplatin-etoposide (PE) (n = 19), as first-, second- and third-line treatment at a tertiary referral centre between 1997 and 2002. Chemotherapy was given every 3 weeks as follows: mitomycin-C (8 mg/m 2) (cycles 1, 2, 4, 6), vinblastine (6 mg/m 2), and cisplatin (50 mg/m 2) all on day 1; and cisplatin (75 mg/m 2) and etoposide (100 mg/m 2) on day 1 and (100 mg/m 2) orally twice a day on days 2-3. Results: The response rate for 40 evaluable patients (MVP: n = 23; PE: n = 17) was 18% (95% confidence interval [CI]: 9-32%). The response rate to MVP was 13% (95% CI: 5-32%, one complete and two partial responses) and to PE 24% (10-47%, four partial responses). Disease stabilised in 43% (26-63%) and 47% (26-69%) of women treated with MVP and PE, respectively. After a median follow-up of 18 months, 37 women (MVP: n = 19; PE: n = 18) died from their disease. Median (range) progression-free survival and overall survival were 6 months (0.4-18.7) and 9.9 months (1.3-40.8), respectively. Median progression-free survival for the MVP and PE groups was 5.5 and 6.2 months (Log-rank, P = 0.82), and median overall survival was 10.2 and 9.4 months (Log-rank, P = 0.46), respectively. The main toxicity was myelosuppression. Grades 3-4 neutropenia was more common in women treated with PE than in women treated with MVP (74% vs 30%; P = 0.012), but the incidence of neutropenic sepsis, relative to the number of chemotherapy cycles, was low (7% overall). The toxicity-related hospitalisation rate was 1.2 admissions per six cycles of chemotherapy. No treatment-related deaths occurred. MVP and PE chemotherapy have modest activity and are safe in women with metastatic breast cancer. © 2005 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Management of endocrine resistant breast cancer

Metastatic breast cancer (MBC) may present de novo but more commonly develops in women initially presenting with early breast cancer despite the widespread use of adjuvant hormonal and cytotoxic chemotherapy. MBC is incurable. Hormone sensitive MBC eventually becomes resistant to endocrine therapy in most women. Anthracyclines are the agents of choice in the treatment of endocrine resistant MBC. With the widespread use of anthracyclines in the adjuvant setting, taxanes have become the agents of choice for many patients. Recently capecitabine has become established as a standard of care for patients pretreated with anthracyclines and taxanes. However, a range of agents have activity as third line treatment. These include gemcitabine, vinorelbine and platinum analogues. The sequential use of non-cross resistant single agents rather than combination therapy is preferable in most women with MBC. Even though combination therapy can improve response rates and increase progression free interval, there is no robust evidence to indicate an advantage in terms of overall survival. Moreover, combination therapy is associated with a higher toxicity rate and poor quality of life. There is no role for dose-intense therapy, high dose therapy or maintenance chemotherapy outside the context of a clinical trial. The introduction of trastuzumab, monoclonal antibody targeting growth factor receptors, has improved the therapeutic options for women with tumours overexpressing HER2/neu. DNA micro-array profiles of tumours can potentially help to individualise therapy in future. Molecular targeted therapy has the potential to revolutionise the management of MBC.

Nanofiber orientation and surface functionalization modulate human mesenchymal stem cell behavior in vitro

Electrospun nanofiber meshes have emerged as a new generation of scaffold membranes possessing a number of features suitable for tissue regeneration. One of these features is the flexibility to modify their structure and composition to orchestrate specific cellular responses. In this study, we investigated the effects of nanofiber orientation and surface functionalization on human mesenchymal stem cell (hMSC) migration and osteogenic differentiation. We used an in vitro model to examine hMSC migration into a cell-free zone on nanofiber meshes and mitomycin C treatment to assess the contribution of proliferation to the observed migration. Poly (ɛ-caprolactone) meshes with oriented topography were created by electrospinning aligned nanofibers on a rotating mandrel, while randomly oriented controls were collected on a stationary collector. Both aligned and random meshes were coated with a triple-helical, type I collagen-mimetic peptide, containing the glycine-phenylalanine-hydroxyproline-glycine-glutamate-arginine (GFOGER) motif. Our results indicate that nanofiber GFOGER peptide functionalization and orientation modulate cellular behavior, individually, and in combination. GFOGER significantly enhanced the migration, proliferation, and osteogenic differentiation of hMSCs on nanofiber meshes. Aligned nanofiber meshes displayed increased cell migration along the direction of fiber orientation compared to random meshes; however, fiber alignment did not influence osteogenic differentiation. Compared to each other, GFOGER coating resulted in a higher proliferation-driven cell migration, whereas fiber orientation appeared to generate a larger direct migratory effect. This study demonstrates that peptide surface modification and topographical cues associated with fiber alignment can be used to direct cellular behavior on nanofiber mesh scaffolds, which may be exploited for tissue regeneration.

Evidence for the role of Mycobacteriumtuberculosis RecG helicase in DNA repair and recombination

In order to survive and replicate in a variety of stressful conditions during its life cycle, Mycobacteriumtuberculosis must possess mechanisms to safeguard the integrity of the genome. Although DNA repair and recombination related genes are thought to play key roles in the repair of damaged DNA in all organisms, so far only a few of them have been functionally characterized in the tubercle bacillus. In this study, we show that M.tuberculosis RecG (MtRecG) expression was induced in response to different genotoxic agents. Strikingly, expression of MtRecG in Escherichiacoli recG mutant strain provided protection against mitomycin C, methyl methane sulfonate and UV induced cell death. Purified MtRecG exhibited higher binding affinity for the Holliday junction (HJ) compared with a number of canonical recombinational DNA repair intermediates. Notably, although MtRecG binds at the core of the mobile and immobile HJs, and with higher binding affinity for the immobile HJ, branch migration was evident only in the case of the mobile HJ. Furthermore, immobile HJs stimulate MtRecG ATPase activity less efficiently than mobile HJs. In addition to HJ substrates, MtRecG exhibited binding affinity for a variety of branched DNA structures including three-way junctions, replication forks, flap structures, forked duplex and a D-loop structure, but demonstrated strong unwinding activity on replication fork and flap DNA structures. Together, these results support that MtRecG plays an important role in processes related to DNA metabolism under normal as well as stress conditions.

Trans-dichlorooxovandium (IV) complex as a novel photoinducible DNA interstrand crosslinker for cancer therapy

Although DNA interstrand crosslinking (ICL) agents such as mitomycin C, cisplatin and psoralen serve as potent anticancer drugs, these agents are known to have dose-limiting toxic effects on normal cells. Moreover, tumor resistance to these agents has been reported. Here, we show that trans-dichlorooxovanadium (IV) complex of pyrenyl terpyridine (VDC) is a novel photoinducible DNA crosslinking agent. By a combination of in vitro and ex vivo experiments including plasmid-based assays, we find that VDC forms monoadducts on the DNA and can be activated by UV-A and visible light to generate DNA interstrand crosslinks. VDC efficiently activates Fanconi anemia (FA) pathway of DNA interstrand crosslink repair. Strikingly, photoinduction of VDC induces prolonged activation of cell cycle checkpoint and a high degree of cell death in homologous recombination (HR)/ICL repair defective cells. Moreover, VDC specifically targets cells that express pathological RAD51C mutants. These data imply that VDC can be potentially used for cancer therapy and suggest that tumors arising in patients with gene mutations in FA and HR repair pathway can be specifically targeted by a photoactivatable VDC.