Transconjunctival application of mitomycin C in combination with laser sclerostomy ab interno: a long-term morphological study of the postoperative healing process

Withaferin A effectively targets soluble vimentin in the glaucoma filtration surgical model of fibrosis

Withaferin A (WFA) is a natural product that binds to soluble forms of the type III intermediate filament (IF) vimentin. Currently, it is unknown under what pathophysiological contexts vimentin is druggable, as cytoskeltal vimentin-IFs are abundantly expressed. To investigate druggability of vimentin, we exploited rabbit Tenon's capsule fibroblast (RbTCF) cell cultures and the rabbit glaucoma filtration surgical (GFS) model of fibrosis. WFA potently caused G₀/G₁ cell cycle inhibition (IC₅₀ 25 nM) in RbTCFs, downregulating ubiquitin E3 ligase skp2 and inducing p27(Kip1) expression. Transforming growth factor (TGF)-ß-induced myofibroblast transformation caused development of cell spheroids with numerous elongated invadopodia, which WFA blocked potently by downregulating soluble vimentin and α-smooth muscle actin (SMA) expression. In the pilot proof-of-concept study using the GFS model, subconjunctival injections of a low WFA dose reduced skp2 expression in Tenon's capsule and increased p27(Kip1) expression without significant alteration to vimentin-IFs. This treatment maintains significant nanomolar WFA concentrations in anterior segment tissues that correspond to WFA's cell cycle targeting activity. A ten-fold higher WFA dose caused potent downregulation of soluble vimentin and skp2 expression, but as found in cell cultures, no further increase in p27(Kip1) expression was observed. Instead, this high WFA dose potently induced vimentin-IF disruption and downregulated α-SMA expression that mimicked WFA activity in TGF-ß-treated RbTCFs that blocked cell contractile activity at submicromolar concentrations. These findings illuminate that localized WFA injection to ocular tissues exerts pharmacological control over the skp2-p27(Kip1) pathway by targeting of soluble vimentin in a model of surgical fibrosis.

Effect of mitomocin C in eosinophilic nasal polyposis, in vivo: concentration of IL5 and GM-CSF, RT-PCR

Eosinophilic nasosinusal polyposis is a chronic inflammatory infection with elevated infiltration of eosinophils, which presents high rate of recurrence after surgical treatment. The continuous inflammatory process that leads to the formation of polyps requires constant clinical treatment. Contributing to the maintenance of eosinophilia are cytokines IL5 (interleukin-5) and GM-CSF (granulocyte macrophages colony-stimulating factor), which show up in elevated concentrations. These oligoproteins diminish the rate of apoptosis and prolong the survival of eosinophils.

Aim

By diminishing these cytokines, the action of Mitomycin C (MMC), an antineoplasic drug which inhibits the synthesis of DNA, was studied. In a recent study the power of this drug to cause apoptosis in eosinophils, in vitro, of nasal polyps was verified.

Methodology

A biopsy of the nasal polyps was undertaken in 15 patients carriers of eosinophilic nasosinusal polyposis 24 hours after applying 0.5 mg/ml of MMC during five minutes. RT-PCR (reverse transcription of polymerase chain reaction) for IL5 and GM-CSF was the method used to obtain the results.

Results

The comparison of the results of GM-CSF pre- and post-application of MMC, when the paired T-test was used, showed p=0.041 and for IL5 we found p<0.001.

Conclusion

Topic use of MMC in patients with eosinophilic nasosinusal polyposis shows statistically significant reduction for GM-CSF and significant and important reduction for IL5.

Tratamento cirúrgico da otite média com efusão: tubo de ventilação versus aplicação tópica de mitomicina C

O uso do tubo de ventilação (TV) da orelha média, tratamento cirúrgico eleito da otite média com efusão (OME), não é isento de complicações, promovendo ainda limitação social pela necessidade de abandono dos banhos de imersão. A mitomicina C (MMC) é um antineoblástico, cuja aplicação tópica retarda a fibrose e previne a estenose cicatricial. Em cobaias, retardou o fechamento de timpanotomias, permitindo maior tempo de aeração da orelha média, à semelhança dos tubos de ventilação. FORMA DE ESTUDO: Clínico prospectivo. OBJETIVO: Comparar a eficácia entre timpanotomia, aspirado da efusão e inserção de tubo de ventilação (grupo TV) versus timpanotomia, aspirado da efusão e aplicação tópica de mitomicina C (grupo MMC). Comparar o tempo de manutenção da timpanotomia e a incidência de complicações nos dois grupos. RESULTADOS: O grupo MMC apresentou eficácia significativamente menor (52% versus 80%) que o grupo TV (p= 0,34). A presença de timpanometria tipo "B" e a ausência de comprometimento do óstio faríngeo tubário pelo tecido adenóide no pré-operatório representaram fatores de mau prognóstico. A aplicação tópica de MMC nas bordas da timpanotomia proporcionou um tempo de abertura da membrana timpânica por duas a três semanas. No grupo TV, a otorréia foi observada em 13,3% dos pacientes. No grupo MMC, apesar da menor eficácia, nenhum paciente apresentou complicações nem sofreu prolongada proibição dos banhos de imersão. CONCLUSÃO: Apesar de concluirmos que o TV apresenta maior eficácia, novos estudos utilizando maior concentração, maior tempo de aplicação ou o uso seriado de MMC no tratamento da otite média com efusão devem ser realizados.

Transconjunctival mitomycin-C in needle revisions of failing filtering blebs

PURPOSE

To report the efficacy and safety of transconjunctival mitomycin-C as an adjunct to needle revision of failing filtering blebs.

DESIGN

Retrospective, consecutive, noncomparative interventional case series.

PARTICIPANTS

Forty-one patients (42 eyes) undergoing bleb revisions by a single surgeon at a single institution from May 1997 to January 2001.

METHODS

The authors retrospectively reviewed charts of 42 eyes that underwent needle revision of the failing filtering bleb using transconjunctival application of mitomycin-C. Needling of the bleb was performed with a 25-gauge needle. The site of the needle puncture was sutured and followed by application of transconjunctival mitomycin-C (0.5 mg/ml) by means of a sponge left in contact with the conjunctival epithelium for 6 minutes. A group of patients received additional subconjunctival injections of 5-fluorouracil in the postoperative period. Success was defined as a reduction in intraocular pressure of 30% without the use of antiglaucoma medications and no further surgical procedures to control intraocular pressure.

MAIN OUTCOME MEASURES

Intraocular pressure, visual acuity, complications, number of glaucoma medications used at the final visit.

RESULTS

Mean preoperative intraocular pressure was 22.1 +/- 8.0 mmHg, which was reduced by 9.6 +/- 7.9 mmHg to a mean postoperative intraocular pressure of 12.5 +/- 6.1 mmHg. Mean follow-up was 17.6 +/- 13.5 months. Kaplan-Meier survival analysis showed a probability of continued success at 12 months of 76.1%, and at 24 months of 71.6%. The most common complication was hyphema in 7.1% of patients. Twenty-six eyes also received postoperative injections of 5-fluorouracil.

CONCLUSIONS

Transconjunctival mitomycin-C may enhance success of the needling procedure in failing filtering blebs.

Histopathology and ultrastructural examination of optic nerve sheath biopsies after optic nerve sheath decompression with and without mitomycin

PURPOSE

We chose to compare histologically and ultrastructurally changes in the optic nerve sheath after optic nerve sheath decompression, initially after a second surgery and after treatment with mitomycin-C. The mechanism by which optic nerve sheath decompression alleviates papilledema can be further understood in consideration of the results.

METHODS

Tissue was obtained by biopsy from 3 first-time surgical and 4 reoperative cases with and without mitomycin-C in patients with idiopathic intracranial hypertension. The sheaths were fixed in a mixture of 2% paraformaldehyde and 2% glutaraldehyde, osmicated and dehydrated in a series of ethanol, and finally embedded in epon. Tissue blocks were sectioned at 1 microm and stained with both PPD and toluidine blue. Thin sections were examined by transmission electron microscopy.

RESULTS

Normal meningeal tissue obtained at the time at optic nerve sheath decompression consisted mainly of collagen, closely packed and roughly parallel to the axis of the optic nerve. Collagen deposition seen in scar tissue after secondary optic nerve sheath decompression was extremely disorganized and irregular, with the individual fibers laid down seemingly at random. There was little sense of layering or of parallel arrays. Mitomycin-C appeared to influence collagen deposition in such a way that the collagen was more regularly packed and more closely resembled unoperated tissue.

CONCLUSIONS

The regular well-organized collagen packing seen in normal sheath tissue is disrupted and replaced by less organized but compact scar tissue after optic nerve sheath decompression. With mitomycin use, more regular collagen packing closely approximating that found in unoperated sheath occurs. This configuration of fibers lends support for the filtration mechanism of optic nerve sheath decompression in treating papilledema.

Impression cytology study of conjunctival epithelial phenotypes on the healing ocular surface after pterygium excision

PURPOSE

To compare the process of conjunctival epithelial regeneration after three types of pterygium excision procedures.

METHODS

Thirty-eight patients (45 eyes) with primary pterygium were randomly assigned to a bare-sclera procedure (group 1, 15 eyes of 12 patients), bare-sclera with intraoperative mitomycin C (MMC 0.02% for 30 seconds; group 2, 15 eyes of 14 patients), or pterygium excision with conjunctival autografting (group 3, 15 eyes of 12 patients). Controls were healthy fellow eyes and seven eyes of age- and sex-matched subjects. Impression cytology was performed preoperatively, at 1 and 2 weeks, and at 1, 3, 6, and 12 months after surgery. The nucleus-to-cytoplasm (N/C) ratio of nongoblet epithelial cells and goblet cell density (GCD) in the pterygial area were calculated and compared over time across treatment groups.

RESULTS

Pterygium excision wounds healed in a similar four-stage process in all groups, but at different rates and with different final results. The N/C ratio was highest at about 1 month postoperatively in groups 1 and 2 and at 2 weeks in group 3, before gradually returning to control levels. Preoperatively, the GCD in treated eyes was almost twice that in control eyes (p = 0.001) but fell to zero immediately postoperatively. Goblet cells first appeared (with the most rapidly increased density) in group 3, followed by group 1. At 12 months, the mean GCD in groups 1 and 3 were not significantly different from those in controls, whereas the mean GCD in group 2 was still less than that of control (p = 0.02).

CONCLUSIONS

Healing of conjunctiva is delayed by MMC and is promoted by autografting. Even 1 year after surgery, the ocular surface remains abnormal with respect to epithelial phenotypes in eyes treated by any of the three techniques.