Different Concentrations Of Mitomycin Research Articles

Cytotoxic and genotoxic effects of mitomycin C toward human endothelial cells

Mitomycin C is the most used for in vitro mutagenesis modeling alkylating agent belonging to the single-site mutagens. In the presented study, the in vitro cytotoxic and genotoxic effects of mitomycin C in endothelial cells of different arteries differ in the level of atherogenesis were studied. MTT colorimetric assay was used for assessment of cytotoxicity of different concentrations of mitomycin C, cytokinesis-block micronucleus assay - for estimating of genotoxic effects in human coronary and internal thoracic artery endothelial cells exposed to mutagen. After 6-h cultivation no decrease in the viability of cell cultures exposed to all studied concentrations of mitomycin C was observed; an increasing time of mutagenic load to 24 hours resulted in a significant (p

Establishment of STO Cell Lines Expressing Green Fluorescent Protein and Mouse Leukemia Inhibitory Factor

To establish the STO cell lines expressing green fluorescent protein (GFP) and mouse leukemia inhibitory factor (LIF) , and try to culture the mouse embryonic stem cells (mESCs) by using the established STO-GFP-mLIF cells as the feeder layer. The lentiviral particles containing GFP and mLIF and puromycin-resistance gene were constructed and transduced into STO cell lines. The cell lines stably expressing GFP and mLIF genes were screened out. The expression level of the inserted exogenous LIF gene was tested by Western blot and ELISA. The STO-GFP-mLIF cells were treated with different concentrations of mitomycin C (5, 10, 15, 20 µg/ml) for different time (1.5, 2.5, 3, 3.5 hours) to prepare feeder layers and the cell proliferation level on feeder layer was observed. Mouse embryonic stem cells were cultured on mitomycin C-treated feeder layer and the growth of cell colonies was observed. The expression level of LIF protein in STO-GFP-mLIF cells was up-regulated, as compared with STO cells (P＜0.05). It was confirmed that the optimal concentration and time for inhibiting the proliferetion of STO-GFP-mLIF cells by mitomycin C were 10 µg/ml and 3 hours respectively. The observation also found that the embryonic stem cells could develop into typic "birdnest" shaped stem cell colony on mitomycin C-treated feeder layer. The stable STO cell lines effectively expressing green fluorescent protein and mouse leukemia inhibitory factor have been established successfully, which can maintain the undifferentiated state of mouse embryonic stem cells.

Mass spectrometry-based Shiga toxin identification: A clinical validation

After we published our preliminary study on the use of liquid chromatography-tandem mass spectrometry (LC-MS/MS) and curated E. coli toxin databases on the identification of E. coli Shiga toxins (Stxs) in the Journal of Proteomics in year 2018, we were encouraged to further refine the method and test clinical isolates. In this study, different concentrations of mitomycin C (MMC) and ciprofloxacin (CF), two common antibiotic/chemotherapy agents capable of stimulating Stx production, were first tested and compared on three reference strains and eight clinical isolates to observe the toxin induction and subsequent identification. Notably, no differences were observed between the two agents other than the concentrations applied. Seventeen more clinical isolates were then tested using fixed MMC and CF concentrations and sample amount. This study confirms that the majority of stx2-positive E. coli strains can be stimulated to produce sufficient toxin for confident identification. This does not occur with stx1-positive E. coli isolates, however, despite the fact that both Stxs can be identified for several isolates without MMC or CF stimulation. Biological significanceStxs, especially Stx2, are very important causes of severe food-borne disease, even death. This study confirms that receptor analogue-based affinity enrichment of Stxs, after MMC or CF treatment of E. coli, is useful for fast and accurate Stx2 identification through LC-MS/MS.

Comparison between Ologen implant and different concentrations of Mitomycin C as an adjuvant to trabeculectomy surgery.

CONTEXT:Trabeculectomy is the most common surgical procedure for treatment of glaucoma. To improve success rates, adjuvants were utilized as Mitomycin C (MMC) and Ologen implant.AIMS:This study aims to establish efficacy and safety of Ologen implant versus MMC in trabeculectomy.SETTING AND DESIGN:A prospective, comparative clinical study was conducted at the Department of Ophthalmology, Assiut University, between December 2014 and April 2016.SUBJECTS AND METHODS:Patients with primary open-angle glaucoma (OAG), primary narrow-angle glaucoma and secondary OAG were assigned equally to trabeculectomy with Ologen, 0.4 mg/mL or 0.2 mg/mL MMC. The study outcome measures were reduction in intra-ocular pressure (IOP), success rates, survival analysis, and rate of complications.STATISTICAL ANALYSIS USED:SPSS software Version 17.0 (SPSS, Inc., IL, USA) was utilized.RESULTS:Thirty eyes were included in the study. Mean baseline IOP in Ologen, MMC 0.4 and MMC 0.2 groups were 27.43 ± 2.97, 28.4 ± 3.24, and 27.56 ± 2.69 mmHg, respectively. At week 24 follow-up, mean IOP in Ologen, MMC 0.4 and MMC 0.2 groups were 18.55 ± 3.18, 16.2 ± 3.22, and 16.93 ± 3.04 mmHg, respectively. No significant inter-group difference was noticed at any visits. Complete success was achieved in 10%, 40%, and 30%, whereas incomplete success in 70%, 50%, and 60%, respectively in Ologen, MMC 0.4 and MMC 0.2 groups. No treatment group difference was reported by Kaplan–Meier analysis. Shallow anterior chamber occurred more in Ologen and MMC 0.4 groups. A single case of serous choroidal effusion had occurred in MMC 0.4 group.CONCLUSION:Ologen implant is a promising alternative to MMC for improving the success rate of trabeculectomy.

Effects of differenta mitomycin C concentrations on laser-assisted subepithelial keratectomy.

The aim of the present study was to determine the effect of different concentrations of mitomycin C (MMC) administered intraoperatively during laser-assisted subepithelial keratectomy (LASEK) surgery. A total of 261 patients (496 eyes) were randomly divided into two groups: 0.04% MMC treatment group consisting of 133 patients (245 eyes) and the 0.02% MMC treatment group consisting of 128 patients (251 eyes). The MMC solutions were dropped intraoperatively onto the ablation region and the duration was dependent on the preoperative refractive power of the patient’s cornea: ≤−3.00 diopters (D), 30 sec; between −3.25 D and −6.00 D, 60 sec; between −6.25 D and −9.00 D, 90 sec and ≥−9.25 D, 110 sec. Postoperative observations included haze formation, visual acuity, changes in refractive power, corneal endothelial cell density and incidence of complications. The one year postoperative incidence of haze differed significantly between the groups (P<0.05). The one week and one year comparisons of postoperative visual acuity also differed significantly between the groups (P<0.05). Postoperative changes in corneal refractive power at one, six and 12 months following surgery significantly differed between the groups (P<0.05). No statistically significant difference was identified between the density of corneal endothelial cells prior to surgery and the density at one, six and 12 months following surgery (P>0.05). Thus, the intraoperative application of 0.04% MMC solution effectively inhibited haze formation and markedly improved the efficacy of LASEK surgery, when compared with that of 0.02% MMC.

Cytotoxicities and Anti-Fibrotic Effects of Pirfenidone and Mitomycin C on Human Fibroblasts

Purpose: The cytotoxicities and anti-fibrotic effects of mitomycin C and pirfenidone on human dermal fibroblast were evaluated. Methods: Initially, 24-hour cell cultures were exposed to transforming growth factor (TGF)-β1, different concentrations of mitomycin C, and pirfenidone solutions in order to evaluate cytotoxicity. Expressions of fibronectin, collagen type 1, α smooth muscle, and β-actin were evaluated by real-time reverse transcription-polymerase chain reaction (RT-PCR) and western blot in mitomycin C solutions at concentrations of 4 μg/mL and 20 μg/mL, and in pirfenidone solutions at 250 μg/mL and 500 μg/mL. Results: In comparison to cell cultures exposed to TGF-β1 solutions, cytotoxicities were increased in solutions of mitomycin C at 4 μg/mL, 20 μg/mL, 40 μg/mL and pirfenidone at 500 μg/mL, 750 μg/mL, 1,000 μg/mL (p < 0.05, Mann Whitney U-test). The results of real-time RT-PCR show that expressions of fibronectin, collagen type 1, and α smooth muscle were significantly more decreased in all concentrations of mitomycin C and pirfenidone compared to those in TGF-β1 solution. In western blot analysis, expressions of fibronectin and α smooth muscle were decreased in all concentrations of mitomycin C and pirfenidone compared to TGF-β1 solution. Conclusions: Both drugs have cytotoxicities and anti-fibrotic effects, but pirfenidone was found to have less cytotoxicity and mitomycin C was found to have more anti-fibrotic effects when compared to each other. J Korean Ophthalmol Soc 2014;55(7):1077-1083

Mitomycin C in Dacryocystorhinostomy

To establish primary cultures of human nasal mucosal fibroblasts (HNMFs) and to test the effect of varying concentrations of mitomycin C (MMC) and treatment durations on cellular proliferation and viability of the fibroblasts. Laboratory investigation. Nasal mucosa harvested from patients undergoing a dacryocystorhinostomy was used to establish primary cultures by explant culture method. Cells were expanded and frozen at every passage, and passage 3 cells were used for further experiments. The cells were then treated with different concentrations of mitomycin C (0.1-0.5 mg/ml) for different time periods (3, 5, and 10 minutes). Cell viability was checked by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay. Cellular proliferation index was determined with bromodeoxyuridine immunostaining. Apoptotic index was measured using annexin A5 affinity assay, propidium iodide staining, and 4',6-diamidino-2-phenylindole counterstaining. The actin cytoskeletons of fibroblasts were studied using phalloidin staining. The doubling time of cultured HNMFs is approximately 24 hours. Similarly, 0.4 mg/ml beyond 5 minutes and 0.5 mg/ml concentration at all time points were lethal and caused extensive cell death when compared with controls. A concentration of 0.2 mg/ml for 3 minutes of exposure prevented cell proliferation of HNMF cells by inducing cell cycle arrest, without causing extensive apoptosis. The minimum effective concentration appears to be 0.2 mg/ml for 3 minutes. This in vitro study could be the starting point for further clinical and histopathologic studies to validate its clinical usefulness.

Differentiation of human amniotic epithelial cells into corneal epithelial-like cells in vitro.

To explore the feasibility that human amniotic epithelial cells (hAECs) have the potential to differentiate into corneal epithelial-like cells under the microenvironment replicated by spontaneously immortalized human corneal epithelial cells (S-ihCECs). hAECs were isolated by enzyme digestion, and flow cytometry was used to analysis the expression of CD29/90/166/73/34 and HLA-DR. Recovered and cultured S-ihCECs, immunocytochemistry was used to detect the expression of CK3/12. The proliferation of S-ihCECs handled by different concentrations of mitomycin was detected by CCK-8. The proliferation of hAECs cultured by S-ihCECs culture media collected at different time was analyzed by CCK-8. After filtered out the optimal conditions, we collected S-ihCECs culture media for 5 days, then prepared conditioned medium to incubate hAECs, inverted phase contrast microscope and scanning electron microscope were used to observe the change of morphology in hAECs. Quantitative real-time reverse transcription-polymerase chain reaction (QRT-PCR) was carried out to evaluate the expression of Oct-4, NANOG, PAX6, and CK12 in the differentiation period. Immunocytochemistry and western bloting were used to detect the expression of CK3/12. The culture media collected every 12h, from 20µg/mL mitomycin pretreatment S-ihCECs could significantly promote the proliferation of hAECs. In the period of differentiation, the morphology of differentiated hAECs was obviously different compared with the control group, and the distinctive CK3/12 for corneal epithelial cells was detected. This study showed that hAECs can differentiate into corneal epithelial-like cells by in vitro replication of the corneal epithelial microenvironment, using the culture media collected from S-ihCECs, and it is possible that S-ihCECs culture media could be used in corneal tissue engineering.

Inhibitory Effect of Mitomycin C on Proliferation of Primary Cultured Fibroblasts from Human Airway Granulation Tissues

Background: Airway granulation tissue and scar formation pose a challenge because of the high incidence of recurrence after treatment. As an emerging treatment modality, topical application of mitomycin C has potential value in delaying the recurrence of airway obstruction. Several animal and clinical studies have already proven its feasibility and efficacy. However, the ideal dosage has still not been determined. Objectives: To establish a novel method for culturing primary fibroblasts isolated from human airway granulation tissue, and to investigate the dose-effect of mitomycin C on the fibroblast proliferation in vitro, so as to provide an experimental reference for clinical practitioners. Methods: Granulation tissues were collected during the routine bronchoscopy at our department. The primary fibroblasts were obtained by culturing the explanted tissues. The cells were treated with different concentrations of mitomycin C (0.1, 0.2, 0.4, 0.8 and 1.6 mg/ml) for 5 min followed by additional 48-hour culture before an MTT assay was performed to measure cell viability. Results: MTT assay showed that mitomycin C reduced cell viability at all tested concentrations. The inhibitory ratios were 10.26, 26.77, 32.88, 64.91 and 80.45% for cells treated with mitomycin C at 0.1, 0.2, 0.4, 0.8 and 1.6 mg/ml, respectively. Conclusions: Explant culture is a reliable method for culturing primary fibroblasts from human airway granulation tissue, and mitomycin C can inhibit proliferation of the fibroblasts in vitro.

Electroporation enhances mitomycin C cytotoxicity on T24 bladder cancer cell line: A potential improvement of intravesical chemotherapy in bladder cancer

Intravesical mitomycin instillation combined with electric pulses is being used experimentally for the treatment of T1 bladder tumors, in patients unfit for surgery. Electroporation may enhance the uptake of chemotherapeutics by permeabilization of cell membranes. We investigated if electroporation improves the cytotoxicity of mitomycin. In two cell lines, T24 (bladder cancer cell line) and DC3F (Chinese hamster fibroblast), exposure to different concentrations of mitomycin (0.01–2000μM) was tested with and without electroporation (6 pulses of 1kV/cm, duration: 99μs, frequency: 1Hz). Cell viability was assessed by colorimetric assay (MTT). For both cell lines, mitomycin's IC_50 was approximately 1000μM in both pulsed and unpulsed cells. On T24 cells, electroporation and mitomycin caused (relative reduction) RR of survival of: 25%, 31% and 29%, by concentrations 0μM, 500μM and 1000μM respectively. For DC3F cells, the RRs of survival were: 28%, 29%, and 33%, by concentrations 0μM, 500μM and 1000μM respectively. In conclusion, electroporation and mitomycin together are about 30% more effective than mitomycin alone. The results help to elucidate the additive effect of mitomycin and electric pulses and support the use of this combination in the treatment of bladder cancer.

Characterization of Bacteriocins Produced by Lactobacillus brevis NM 24 and L.fermentum NM 332 Isolated from Green Olives in Iran

The aim of the study was to isolate and characterize bacteriocin producing Lactic Acid Bacteria (LAB) from local olive samples and to exploit their potential as biopreservative. The two lactobacillus strains namely L.brevis NM 24 and L.fermentum NM 332, exhibiting wide spectrum of activity against closely related strain were selected and screened for their bacteriocin producing ability. Cell free supernatant fluid collected from both the isolates was sensitive to the action to proteolytic enzymes, and complete loss of their antagonistic activity was seen. Several gram positive and gram negative pathogens such as Bacillus subtilis, Enterococcus faecalis, Escherichia coli, Listeria monocytogenes, and Staphylococcus aureus were inhibited by the inhibitory action of bacteriocins in study. The bacteriocinogenic potential in these strains appeared non-inducible and no increase in their titer was observed after exposure to different concentrations of Mitomycin C and UV light.The concentrated crude bacteriocin samples subjected to ammonium sulphate precipitation resulted in an increased activity and high protein yield. During ultrafiltration studies, bacteriocin NM 332 produced by L.fermentum NM 332, was able to pass through the cellulose membranes with 10 KDa and 30KDa molecular weight cut off indicating the presence of a small protein molecule. By non-denaturing gel a band of approximately 8 KDa for L.fermentum NM 332 and band corresponding to 37 KDa in L.brevis NM 24 was seen. Physicochemical characterization of the partially purified bacteriocin samples indicated heat (121°C for 60 min) and acidic pH stability (pH 2-6) of bacteriocin NM 24. Exposure to surfactants resulted in a significant increase in the bacteriocin titer of both the strains, except for Tween 20 which resulted in complete loss of activity. None of the strains showed presence of plasmids indicating chromosomal associated genes responsible for bacteriocin production. The bactericidal activity displayed by the bacteriocins in study was maintained during storage at -20 °C for more than three years.

Effect of Needle Revision of Failed Filtering Blebs with Different Concentrations of Mitomycin C

Purpose: To investigate the efficacy and the risk factors for failure and complications of mitomycin C (MMC)-augmented needle revision (NR) of failed filtering blebs. Methods: Thirty eyes whose intraocular pressure (IOP) did not decrease after the cutting of scleral flap sutures were recruited. NR was performed with a 26-gauge needle under a slit-lamp. Immediately following NR, all eyes received a subconjunctival injection of 0.1 ml of 0.02 mg/ml (group A) or 0.1 mg/ml (group B) MMC at the adjacent conjunctiva. The mean follow-up period after the last needle revision was 13.2±4.2 months. Results: The mean IOP decreased from 25.7±10.6 mmHg before surgery to 13.7±2.5 mmHg at the last follow-up in group A and from 24.1±6.8 mmHg to 17.7±8.6 mmHg in group B (group A: p=0.001, group B: p=0.065). Subconjunctival hemorrhage, hyphema, and a shallow anterior chamber appeared in most cases. However, choridal detachment and avascular changes of the conjunctiva were observed in group B. Conclusions: IOP decreased in both groups A and B, but severe complications appeared only in group B. NR followed by a subconjunctival injection of 0.02 rather than 0.1 mg/ml is a safe and effective method. J Korean Ophthalmol Soc 49(6):951-957, 2008

Immobilization as a technical possibility for long-term storage of bacterial biosensors

For applications in field experiments, the recombinant strain Salmonella typhimurium TA1535 was immobilized to permit its immediate utilization after long storage periods. Salmonella typhimurium TA1535 cells contain the plasmid that has an inducible SOS promoter fused to a promoterless luxCDABFE operon from Photobacterium leiognathi. The induction of bioluminescence occurs in the presence of the DNA-damaging agent mitomycin C which stimulates the bacterial SOS response. Early stationary phase cells were immobilized at a cell concentration of 10(10) CFU/ml in microtiter plates and stored up to 6 weeks at 4 degrees C in a sealed container. Even after 4 weeks of storage, the bioluminescence kinetics and yield in response to different concentrations of mitomycin C were not significantly different from those of freshly prepared samples.

Long-Term Results of Trabeculectomy With Different Concentrations of Mitomycin C in Refractory Developmental Glaucoma

To evaluate the long-term results of trabeculectomy with two different concentrations of mitomycin C in refractory developmental glaucoma. A total of 48 eyes of 37 patients with previous failure of congenital glaucoma surgery underwent mitomycin C-augmented trabeculectomy. Data were analyzed retrospectively, and patients were divided into two groups. Group 1 consisted of 18 patients (25 eyes) who underwent trabeculectomy with a 0.4 mg/mL mitomycin C solution and group 2 consisted of 19 patients (23 eyes) who underwent trabeculectomy with a 0.2 mg/mL mitomycin C solution. Pre- and postoperative intraocular pressure (IOP), best-corrected visual acuity, bleb characteristics, success rate, and complications were compared for both groups. Mean time between primary surgery and mitomycin C-augmented trabeculectomy was 19.3 months (range, 11 months to 7 years). Mean preoperative IOP was 28.4 +/- 2.9 mm Hg in group 1 and 29.0 +/- 2.4 mm Hg in group 2. Final postoperative IOP was 17.0 +/- 1.6 for group 1 and 17.1 +/- 1.4 mm Hg for group 2. There were no significant differences between the groups for IOP, success rate, and complications (P > .05). The most common postoperative complication was shallow anterior chamber (11 [22.9%] of 48 eyes). A 0.4 or 0.2 mg/mL mitomycin C solution for 4 minutes may be used during trabeculectomy in refractory developmental glaucoma.

Mutagenic activity of ambient oxygen and mitomycin C in Fanconi's anaemia cells.

Cellular evidence suggests that Fanconi's anaemia (FA) might be a condition of increased oxygen sensitivity. In order to test this hypothesis, a common shuttle vector assay with the plasmid pZ189 was utilized. We transfected intact, circular plasmid into FA and control lymphoblast and fibroblast host cells maintained at 5 and 20% O2 (v/v). In parallel experiments, host cells were exposed to different concentrations of mitomycin C (MMC), a cross-linking agent towards which FA cells are known to be hypersensitive. Baseline mutation frequencies at 20% oxygen were significantly higher in plasmids passaged through FA lymphoblasts or FA fibroblasts in comparison with passage through the corresponding control cells. Lowering the oxygen concentration during the 48 h transfection period to 5% resulted in a significant decrease of mutation frequencies in plasmids passaged through FA cells. Sequence analysis of plasmids recovered from FA lymphoblasts revealed a mutation hot spot (22% of point mutations with G:C to A:T base substitutions) at base 117 of the supF tRNA gene. This hot spot was present only at 20% oxygen. 59% of the base changes at the hot spot and 39% of the changes elsewhere in the supF gene were C to T transitions (the corresponding figures are 0 and 27% at 5% oxygen), the most common type of base change induced by oxygen. The mutation spectrum observed suggests a role for 8-hydroxydeoxyguanosine in G:C to A:T base substitutions: at 20% oxygen, FA cells displayed 4 times as many G:C to T:A transversions than FA cells kept at 5% O2. In MMC treated cells the decrease in plasmid survival is dose dependent and more pronounced in FA than control cells. Mutation analysis shows similar rates of deletions for both control and FA cells. However, FA cells generate a specific type of deletion whose breakpoint involves an indirect repeat that corresponds to a heptamer signal sequence commonly seen at recombination sites. Together our data provide compelling evidence that the genetic defect in FA causes oxygen sensitivity and recombinational types of DNA lesions following exposure to MMC.

Effects of mitomycin C on the rat retina

To evaluate the retinal toxicity of mitomycin C injection in the rat eye, we conducted an electroretinographic study and a histopathologic study. Three different concentrations of mitomycin C (0.2, 0.3 and 0.4 mg/ml) were injected into either the vitreous cavity or the anterior chamber of the experimental eyes. A full-field electroretinogram was recorded before injection and 2, 4 and 7 days after injection. The retinas of all eyes were examined by light and electron microscopy. We found no evidence of electroretinographic and histologic changes 2 and 7 days after injection of 0.4 mg/ml of mitomycin C into the anterior chamber. However, profound electroretinographic changes did follow injection of the drug into the vitreous. These were absent with the 0.2-mg/ml solution at 7 days, mild with the 0.3-mg/ml solution at 7 days and profound with the 0.4-mg/ml solution as early as 2 days. Intravitreal injection of 0.4 mg/ml, however, showed selective degeneration of Müller cell process at day 2, retinal pigment epithelium changes at day 4 and irregular arrangement of the outer nuclear layer and photoreceptors at day 7. Intravitreal injection of mitomycin C in a concentration comparable to the one used clinically could cause retinal disorders, both functionally and histologically.

Intraocular toxicity to ciliary nerves after extraocular application of Mitomycin C in rabbits

Prolonged postoperative hypotony is a severe complication frequently associated with trabeculectomies performed with a single perioperative application of Mitomycin C. We performed an animal experiment using 8 pigmented rabbits applying different concentrations of Mitomycin C, ranging from 0.05 to 1.0 mg/ml, under the conjunctiva on the intact sclera for 5 minutes. The eyes were examined by light and electron microscopy after 4 weeks. The nerves within the ciliary body in areas adjacent to the region of treatment showed toxic effects related to the concentrations of Mitomycin C applied. In cases where small concentrations were used, only the unmyelinated nerves were damaged with the myelinated remaining intact. In eyes treated with high concentrations, both groups of nerves exhibited severe signs of destruction. This effect is likely to compromise the production of aqueous humor in rabbits, and possibly also in humans.

Effects of Intraoperative 5-Fluorouracil or Mitomycin C on Glaucoma Filtration Surgery in the Rabbit

To establish the effects of single intraoperative exposures to either 5-fluorouracil (5-FU) or two different concentrations of mitomycin C (MMC) on filtration surgery in the rabbit. A prospective, randomized, masked-observer, placebo-controlled study was performed to compare the effects on filtration surgery in rabbits of a single 5-minute intraoperative exposure to 5-FU (50 mg/ml), MMC (0.2 mg/ml), or MMC (0.4 mg/ml) with control eyes treated with distilled water. Intraocular pressures (IOPs) remained lower for longer and bleb survival was increased (P < 0.05) with all three treatments compared with control eyes. The effect of 5-FU was more transient than MMC. Bleb survival was prolonged in the following order: MMC 0.4 > MMC 0.2 > 5-FU 50 mg/ml. At 30 days, blebs were present in 100% of eyes treated with MMC 0.4 mg/ml, 60% of eyes treated with MMC 0.2 mg/ml, and 0% of eyes treated with 5-FU 50 mg/ml or distilled water. The blebs in the eyes treated with MMC were thinner, and significant complications (endophthalmitis, transient corneal opacification and neovascularization, and a presumed bleb leak) only occurred in the eyes treated with MMC 0.4 mg/ml. The authors' results suggest that 5-FU and MMC at these concentrations, delivered as a single intraoperative dose, prolong the survival of filtration surgery for different lengths of time in the rabbit, which is a model that normally exhibits aggressive healing and rapid failure of filtration surgery. The implications of these potentially titratable effects for filtration surgery in different categories of patients are discussed.

Sister chromatid exchanges and chromosomal aberrations induced by mitomycin C in mouse lymphocytes carrying a leukemogenic virus.

The induction of chromosomal damage (sister chromatid exchanges (SCEs), chromosomal aberrations, and micronuclei) in T lymphocytes from mouse spleen was analyzed after treatment in vivo with different concentrations of mitomycin C (MMC). Lymphocytes were derived from BALB/Mo mice, which carry an endogenous type C retrovirus (Moloney murine leukemia virus, M-MuLV), and from BALB/c mice (controls, M-MuLV-free). Chromosomal damage was determined in vitro on lymphocytes stimulated with concanavalin A (Con A) and incubated for two generation cycles with bromodeoxyuridine (BUdR). The baseline frequency of SCEs was significantly higher in untreated BALB/Mo than in BALB/c lymphocytes. The frequencies of SCEs were significantly increased by increasing doses of MMC in both BALB/c and BALB/Mo T lymphocytes. Treatment with a low dose of MMC (0.3 mg/kg) produced an additive effect on SCE frequency in BALB/Mo lymphocytes, which was gradually suppressed by increasing the MMC concentration (3-5 mg/kg). Indeed, the levels of SCEs became significantly lower in BALB/Mo than in BALB/c lymphocytes at the highest MMC concentration tested (10 mg/kg), indicating that a negative synergistic effect was eventually produced. Chromosomal aberrations (breaks and total aberrations) were significantly increased by the highest MMC doses (5-10 mg/kg) and were more frequent in BALB/Mo than in BALB/c lymphocytes at 10 mg/kg MMC. The frequencies of micronuclei were increased by all MMC doses and were significantly higher in BALB/Mo than in BALB/c lymphocytes at 10 mg/kg MMC. These results are referred to interferences of M-MuLV and MMC with the function of enzymes, such as DNA topoisomerases, involved in the mechanism of SCE production.