Intracameral bevacizumab and mitomycin C Trabeculectomy for eyes with neovascular glaucoma: a case series

The purpose of this study was to describe the surgical outcomes and safety of intracameral bevacizumab during trabeculectomy in eyes with neovascular glaucoma. Pilot study included four eyes (four patients) with refractory neovascular glaucoma submitted to fornix-based trabeculectomy with adjunctive use of bevacizumab in the anterior chamber during the procedure. Patients were previously treated with panretinal photocoagulation as standard therapy. Variables evaluated were intraocular pressure, bleb appearance, iris neovascularization, intraoperative/postoperative complications, and visual outcomes. No intraoperative complication was observed. The mean follow-up period was 12.75 (range, 12–15 months). All eyes showed significant intraocular pressure control postoperatively. Iris neovascularization reduced significantly within 1 month after surgery. Mild anterior chamber inflammation was observed during follow-up in all eyes. No significant postoperative complication was observed, and no patient presented visual acuity deterioration. Intracameral bevacizumab may be used as an adjunctive therapy during trabeculectomy in eyes with neovascular glaucoma.     

Interactions of surface-confined DNA with electroreduced mitomycin C comparison with acid-activated mitomycin C

The anticancer activity of the antineoplastic drug mitomycin C (MC) was investigated using transfer stripping cyclic voltammetry (TSCV) with single-stranded DNA-modified hanging mercury drop electrode (HMDE). Reductive activation of MC is necessary for drug covalent binding to DNA, and we have found that some potential-controlled interactions of MC with DNA occur at the electrode, i.e. MC can be activated by electroreduction. Acid and electroreductive MC activations were compared and different adducts were subsequently generated, suggesting that the drug can bind to DNA in more than one way. Under conditions of acid activated MC, a monofunctional adduct between C-1 of MC and N-7 of guanine was formed on the electrode surface, reduced at - 0.44 V (vs. SCE). However, when the DNA-modified electrode was immersed in a MC solution and potentials corresponding to the quinone moiety reduction (- 0.3 V or more negative vs. SCE) were applied, an intrastrand bifunctional adduct between C-1 and C-10 of MC and two N-7 of a pair of adjacent guanines in ssDNA were formed at the electrode, reduced at - 0.49 V, i.e. 50 mV more negative than the monoadduct. The results presented in this paper show for the first time electrochemical detection of DNA-MC adducts at the hanging mercury drop electrode.     

Interaction of the antitumor antibiotic mitomycin C with Z-DNA

Mitomycin C (MC), an antitumor antibiotic, alkylated Z-DNAs such as poly(dG-dC)/Co(NH3)3+(6), poly(dG-m5dC)/Mg2+ and brominated poly(dG-dC) upon reductive activation. Computer-generated energy-minimized molecular models indicated that monofunctional alkylation of Z-DNA at the N2-position of guanine by MC did not distort Z-DNA geometry, but bifunctional alkylation, leading to interstrand crosslinks between two N2-positions of guanine was sterically unfavorable. The above three Z-DNA's were exposed both to monofunctionally and bifunctionally activated MC in separate experiments and the resulting covalent MC-polynucleotide complexes were examined for conformation and for covalent MC-adducts, by circular dichroism (CD) spectroscopy and HPLC analysis of nuclease digests, respectively. Monofunctionally activated MC alkylated all three polynucleotides in their Z-forms, resulting in the same monofunctional N2-guanine adduct as that known to be formed with B-DNA. Upon bifunctional activation of MC, poly(dG-dC/Co(NH3)3+(6) reverted to the B-form and bifunctional (cross-link) adducts were detected, identical again with those formed with B-DNA. Poly(dG-m5dC), however, remained in the Z-form after the alkylation and only a monofunctional adduct could be detected. It was concluded that Z-DNA is subject to monofunctional alkylation by MC but cannot be cross-linked. The latter process occurs only when the Z-DNA is labile enough [as is in the case of poly(dG-dC)] to have some B-form in equilibrium at the site of the first formed monolinked adduct; the cross-linking then occurs at such local B-sites, pulling the overall B in equilibrium Z equilibrium irreversibly to the left. These results are in accord with the predictions from the above modeling. The irreversible "lock" by the MC cross-link on B-DNA may be exploited for probing Z-DNA intermediacy in various DNA functions.     

Decomposition of ribosomal particles in Escherichia coli treated with mitomycin C

Exposure of cells of Escherichia coli to mitomycin C (5 mug/ml) resulted in a marked change in the sedimentation profiles of the cell-free extracts, indicating a specific decomposition of ribosomal particles. When the extracts were prepared in the presence of 0.01 m Mg(++) and analyzed by sucrose density gradient centrifugations, the 100S fraction disappeared rapidly from the treated cells. The 70S ribosomes were also degraded, but more slowly, with a concomitant accumulation of a fraction having a sedimentation coefficient of about 50S. However, decomposition of the 70S ribosomes was preceded by an almost complete loss of the 50S ribosomal subunits, as revealed by sedimentation analyses in the presence of 10(-4)m Mg(++). Synthesis of the ribosomes in the treated cells was also suppressed, being demonstrated by a lower incorporation of uracil-2-(14)C into the ribosomal fractions. However, the change in the ribosomal profile in the treated cells apparently resulted from the decomposition of pre-existing ribosomes, rather than from the inhibition of the net synthesis of ribosomes. Sedimentation analyses and chromatography of the nucleic acids extracted from the treated cells indicated extensive but delayed degradation of the ribosomal ribonucleic acid (RNA), but not of the soluble RNA or deoxyribonucleic acid fractions. Altered structure of the ribosomes in the treated cells was also indicated by their lower melting temperature, broadened thermal profile, higher electrophoretic mobility, and extreme sensitivity to ribonuclease treatment, compared with normal ribosomes. The synthesis of messenger RNA was inhibited progressively with time in the treated cells.     

Inhibition of DNA cross-linking by mitomycin C by peroxidase-mediated oxidation of mitomycin C hydroquinone.

Mitomycin C requires reductive activation to cross-link DNA and express anticancer activity. Reduction of mitomycin C (40 microm) by sodium borohydride (200 microm) in 20 mm Tris-HCl, 1 mm EDTA at 37 degrees C, pH 7.4, gives a 50-60% yield of the reactive intermediate mitomycin C hydroquinone. The hydroquinone decays with first order kinetics or pseudo first order kinetics with a t(12) of approximately 15 s under these conditions. The cross-linking of T7 DNA in this system followed matching kinetics, with the conversion of mitomycin C hydroquinone to leuco-aziridinomitosene appearing to be the rate-determining step. Several peroxidases were found to oxidize mitomycin C hydroquinone to mitomycin C and to block DNA cross-linking to various degrees. Concentrations of the various peroxidases that largely blocked DNA cross-linking, regenerated 10-70% mitomycin C from the reduced material. Thus, significant quantities of products other than mitomycin C were produced by the peroxidase-mediated oxidation of mitomycin C hydroquinone or products derived therefrom. Variations in the sensitivity of cells to mitomycin C have been attributed to differing levels of activating enzymes, export pumps, and DNA repair. Mitomycin C hydroquinone-oxidizing enzymes give rise to a new mechanism by which oxic/hypoxic toxicity differentials and resistance can occur.     

Alkylation of calf thymus DNA with reductively activated mitomycin C

Mitomycin C (MMC) was catalytically reduced in the presence of a nucleotide or calf thymus DNA. Reaction with 5'-guanylic acid (5'-GMP) gave 1,2-cis-2, 7-diamino-1-(5'-guanylyl) mitosene. Reaction with calf thymus DNA gave modified DNA, which on enzymatic hydrolysis gave two alkylated 5'-deoxyguanylic acid (MG-1 and MG-2) and an alkylated 5'-deoxyadenylic acid (MA). This is the first example of isolation of nucleotides from DNA modified by MMC.     

小梁切除术中应用丝裂霉素C 对角膜内皮细胞的影响

目的:观察小梁切除术中应用丝裂霉素C(MMC)对角膜内皮细胞的影响。方法:收集2010年9月2011年5月在我院行小梁切除术的青光眼患者60例(78眼),随机分为术中应用丝裂霉素C的36例(46眼)患者为A组,术中不用丝裂霉素C的24例(32眼)为B组,分别观察术前、术后1个月和术后3个月两组眼压(IOP)、角膜内皮细胞的密度(CD)、平均细胞面积(AVG)及细胞面积变异系数(CV),分析其数量的改变及两组间的差异。结果:A组术前眼压为(35.4±13.7)mmHg,B组术前眼压为(32.5±13.5)mmHg差异无统计学意义(P>0.05),A组术后1个月及术后3个月眼压分别为(15.7±3.7)mmHg、(17.0±3.2)mmHg,均低于B组的(19.4±3.7)mmHg、(20.2±2.1)mmHg,差异有统计学意义(P<0.05)。A组术前、术后1个月及术后3个月角膜内皮细胞密度分别为(2475±484)个/mm2、(2199±373)个/mm2、(2164±332)个/mm2;平均细胞面积分别为(431.4±67.6)μm2、(480.6±66.8)μm2、(463.8±46.2)μm2;细胞面积变异系数分别为(31.1±7.4)%、(34.4±6.3)%、(31.2±7.5)%;术后1个月及术后3个月各参数与术前比较,差异均有统计学意义(P<0.05)。B组术前、术后1个月及术后3个月角膜内皮细胞密度分别为(2342±94)个/mm2、(2185±215)个/mm2、(2074±218)个/mm2;平均细胞面积分别为(453.9±94.8)μm2、(516.3±100.8)μm2、(499.81±106.4)μm2;细胞面积变异系数分别为(30.2±3.0)%、(32.7±2.9)%、(31.4±4.3)%;除术后3个月角膜内皮细胞与术前比较有意义(P<0.05)外,余参数术后1个月及术后3个月与术前比较差异均无统计学意义(P>0.05)。术后1个月A组的角膜内皮细胞丢失率为10.4%高于B组的6.1%,差异有统计学意义(P<0.05);术后3个月A组的角膜内皮细胞丢失率为11.1%高于B组的10.0%,差异无统计学意义(P>0.05)。结论:小梁切除术中用丝裂霉素C的降压效果比不用丝裂霉素C的效果好,但短期内前者角膜内皮细胞的丢失率高于后者。     

Sequence-specific DNA damage induced by reduced mitomycin C and 7-N-(p-hydroxyphenyl)mitomycin C.

Mitomycin C reduced with sodium borohydride induced the DNA damage at deoxyguanosines preferentially in dinucleotide sequence G-T. The DNA damage produced strand breaks when subsequently heated. The DNA damage scarcely occurred when the end-labeled DNA was preincubated with ethidium bromide or actinomycin D before the addition of mitomycin C and the reducing agent. Fully reduced mitomycin C did not induce the DNA damage. The mitomycin C-inducing DNA damage seems to require the intercalation of the partially reduced mitomycin C of short life time, probably semiquinone radical, between DNA base pairs. The inhibitory effects of sodium chloride and radical scavengers suggested that the requirement of the covalent bond formation of mitomycin C to DNA and the involvement of oxygen radicals in the DNA damage. 7-N-(p-hydroxyphenyl)mitomycin C, which is reported to show a higher antitumor activity and a lower toxicity than mitomycin C, was readily reduced with dithiothreitol and induced the sequence-specific DNA damage, whereas mitomycin C was not.     

小梁切除术中应用丝裂霉素C对角膜内皮细胞的影响

目的：观察小梁切除术中应用丝裂霉素C（MMC）对角膜内皮细胞的影响。方法：收集2010年9月2011年5月在我院行小梁切除术的青光眼患者60例（78眼）,随机分为术中应用丝裂霉素c的36例（46眼）患者为A组,术中不用丝裂霉素c的24例（32眼）为B组。分别观察术前、术后1个月和术后3个月两组眼压（10P）、角膜内皮细胞的密度（co）、平均细胞面积（AVG）及细胞面积变异系数（cv）,分析其数量的改变及两组间的差异。结果：A组术前眼压为（35．4±13．7）mmHg,B组术前眼压为（32．5±13．5）mmHg差异无统计学意义（P〉0．05）,A组术后1个月及术后3个月眼压分别为（15．7±3．7）mmHg、（17．0±3．2）mmHg,均低于B组的（19．4±3．7）mmHg、（20．2±2．1）mmHg,差异有统计学意义（P〈0．05）。A组术前、术后1个月及术后3个月角膜内皮细胞密度分别为（2475±484）个／mm2、（2199±373）个／mm2、（2164±332）个／mm2;平均细胞面积分别为（431．4±67．6）μm2、（480．6±66．8）μm2、（463．8±46．2）μm2;细胞面积变异系数分别为（31．1±7．4）％、（34．4±6．3）％、（31．2±7．5）％;术后1个月及术后3个月各参数与术前比较,差异均有统计学意义（P〈0．05）。B组术前、术后1个月及术后3个月角膜内皮细胞密度分别为（2342±94）个／mm2、（2185＋215）个／mm2、（2074218）个／mm2;平均细胞面积分别为（453．9土94．8）μm2、（516.3±100．8）μm2、（499．81＋106．4）μm2;细胞面积变异系数分别为（30．2土3．0）％、（32．7±2．9）％、（31．4±4．3）％;除术后3个月角膜内皮细胞与术前比较有意义（P〈0．05）外,余参数术后1个月及术后3个月与术前比较差异均无统计学意义（P〉0．05）。术后1个月A组的角膜内皮细胞丢失率为10．4％高于B组的6．1％,差异有统计学意义（P〈0．05）;术后3个月A组的角膜内皮细胞丢失率为11．1％高于B组的10．0％,差异无统计学意义（P〉0．05）。结论：小梁切除术中用丝裂霉素C的降压效果比不用丝裂霉素C的效果好,但短期内前者角膜内皮细胞的丢失率高于后者。     

Reductive activation of mitomycin C and mitomycin C metabolites catalyzed by NADPH-cytochrome P-450 reductase and xanthine oxidase

Under anaerobic conditions and with proper electron donors, NADPH-cytochrome P-450 reductase (EC 1.6.2.4) and xanthine oxidase (EC 1.2.3.2) similarly reductively metabolized mitomycin C. Reversed phase high performance liquid chromatography was used to separate, detect, and isolate several metabolites. Three metabolites were identified by mass spectrometry and thin layer chromatography as 1,2-cis- and trans-2,7-diamino-1-hydroxymitosene and 2,7-diaminomitosene. Three metabolites were phosphate-dependent, and two of them were identified to be 1,2-cis- and trans-2,7-diaminomitosene 1-phosphate. The amounts of the five identified metabolites generated during the reduction of mitomycin C varied with pH and nucleophile concentration. At pH 6.5, 2,7-diaminomitosene was essentially the only metabolite formed, whereas from pH 6.8 to 8.0, trans- and cis-2,7-diamino-1-hydroxymitosene increased in quantity as 2,7-diaminomitosene decreased. The disappearance of mitomycin C and the production of metabolites were enzyme and mitomycin C concentration-dependent. Substrate saturation was not reached for either enzyme up to 5 mM mitomycin C. Electron paramagnetic resonance studies demonstrated the formation of mitomycin C radical anion as an intermediate during enzymatic activation. Our results indicate that either enzyme catalyzed the initial activation of mitomycin C to a radical anion intermediate. Subsequent spontaneous reactions, including the elimination of methanol and the opening of the aziridine ring, generate one active center at C-1 which facilitates nucleophilic attack. Simultaneous generation of two reactive centers was not observed. All five primary metabolites were metabolized further by either flavoenzyme. The secondary metabolites exhibited similar changes in their absorbance spectra and were unlike the primary metabolites, suggesting that a second alkylating center other than C-1 was generated during secondary activation. We propose that secondary activation of monofunctionally bound mitomycin C is probably a main route for the bifunctional binding of mitomycin C to macromolecules and that the cytotoxic actions of mitomycin C result from multiple metabolic activations and reactions.     

Action of mitomycin C on mouse spermatogonia

The induction of chromosome aberrations in mouse spermatogonia and bone marrow cells by treatment with Mitomycin (MC) was tested. The following dosages were used: 3.5; 1.75; 0.35; and 0.035 mg/kg body weight. Chromatid interchanges and terminal deletions were induced in both tissues. Regarding the chromosome damage, spermatogonia seemed to be more sensitive to the test substance than bone marrow cells.The aberrations observed were considered to represent the cause of dominant lethals induced in spermatocytes after treatment with MC by others. The squash technique adapted for examination of mitoses of mouse spermatogonia proved to be a useful tool in testing potential chemical mutagens.     

Comparative cytogenetic study after treatment of mouse spermatogonia with mitomycin C

Male (101 × C₃H)F₁ hybrid mice, 10–12 weeks old, were injected i.p. with single doses of 2.5, 3.75 or 5.0 mg/kg of mitomycin C (MC). Spermatogonia were sample for mitotic chromosome analyses 6, 18 or 24 h after treatment. Spermatocytes were sample for meiotic chromosome analyses 50 or 60 days after treatment.The maximal yield of chromatid-type aberrations induced in spermatogonia was found 24 h after treatment with 5.0 mg/kg of MC. More than 50% of the cells carried at least one chromatid exchange. The majority (90%) of these were whole-arm exchanges derived from breaks in the centromeric heterochromatin.No translocation multivalents were found in spermatocytes analysed 50 or 60 days after treatment. The discrepancy between the presence of many symmetrical exchanges in spermatogonia and the absence of translocation multivalents in primary spermatocytes may be result of insensitivity of the stem cell spermatogonia against exchange induction by MC or of complete germinal selection against induced translocations before and/or during early meiosis. However, the possibility of missing translocations due to whole-arm exchanges in acrocentric chromosomes during the analysis of diakineses-metaphases I is also discussed.It is emphasized that comparisons of chromatid exchange frequencies in spermatogonia with the yield of translocation multivalents in spermatocytes descended from these spermatogonia as opposed to those from stem cells might provide an estimate of pre-diakinesis germinal selection against chromatid exchanges or the resulting translocations. This estimate is important for the quantitative evaluation of the genetic risk from environmental mutagens.     

Efficacy of mitomycin C against alveolar Echinococcus

Mitomycin C was tested against the metacestode stage of Echinococcus multilocularis in jirds. The efficacy of 61-76% was achieved within 1 month of treatment with a total dose of 0.04, 0.08 or 0.3 mg.     

Genetic variants associated with primary open angle glaucoma in Indian population

Glaucoma is a very common disorder of the eye wherein the disturbance of the structural or functional integrity of the optic nerve causes characteristic atrophic changes in the optic nerve, which may lead to specific visual field defects over time. Primary open angle glaucoma (POAG) is most frequent among the three principle glaucoma subtypes. With well-established role of genes like Myocilin (MYOC), Optineurin (OPTN) and WD repeat Domain 36, (WDR36), at least 29 genetic loci have been found till date to be linked to POAG. Moreover, association studies have found 66 loci with 76 genes associated to POAG till date with conflicting results. This particular study is to summarize the current knowledge regarding the change in glaucoma prevalence worldwide and in India from 1993 onwards and compiles all the studied genes that are involved in POAG pathogenesis in Indian population.     

Reactivity of mitomycin C with synthetic polyribonucleotides containing guanine or guanine analogs

The guanine residues in nucleic acids are believed to be the major covalent binding site of the antibiotic mitomycin C. To identify the specific functional group in guanine which reacts with mitomycin C, reactions were run between the antibiotic and poly(G) analogs in which guanine was blocked at the N-7 or O-6 position, or lacked the 2-amino group. Binding ratios were affected to a small extent in the two former cases, but binding was significantly decreased in the absence of the 2-amino group. These results indicate that the most likely binding site of mitomycin C in synthetic polyribonucleotides is the 2-amino group of guanine residues.