Engineering of Ocriplasmin Variants by Bioinformatics Methods for the Reduction of Proteolytic and Autolytic Activities

BACKGROUND

Ocriplasmin has been developed for the induction of posterior vitreous detachment in patients with vitreomacular adhesion. At physiological pH, ocriplasmin is susceptible to autolytic and proteolytic degradation, limiting its activity duration. These undesirable properties of ocriplasmin can be reduced by site-directed mutagenesis, so that its enzymatic activities can be augmented. This study aimed to design ocriplasmin variants with improved biological/physicochemical characteristics via bioinformatics tools.

METHODS

This study was performed in Tabriz University of Medical Sciences, Tabriz, Iran, 2019. Through site-directed mutagenesis, three ocriplasmin variants were designed. Structural analysis was performed on the wild-type variant and the mutant variants using the Protein Interactions Calculator (PIC) server. The interactions between the S-2403 substrate and the ocriplasmin variants were studied by molecular docking simulations, and binding capability was evaluated by the calculation of free binding energy. The conformational features of protein-substrate complex systems for all the variants were evaluated using molecular dynamic simulations at 100 nanoseconds.

RESULTS

The structural analysis of ocriplasmin revealed that the substitution of threonine for alanine 59 significantly reduced proteolytic activity, while the substitution of glutamic acid for lysine 156 influenced autolytic function. The molecular docking simulation results indicated the appropriate binding of the substrate to the ocriplasmin variants with high-to-low affinities. The binding affinity of the wild-type variant for the substrate was higher than that between the mutant variants and the substrate. Simulation analyses, consisting of the root-mean-square deviation, the root-mean-square fluctuation, and the center-of-mass average distance showed a higher affinity of the substrate for the wild type than for the mutant variants.

CONCLUSION

The mutational analysis of ocriplasmin revealed that A59T and K156E mutagenesis could be used for the development of a new variant with higher therapeutic efficacy.

OCRIPLASMIN FOR VITREOMACULAR TRACTION IN CLINICAL PRACTICE: The INJECT Study

PURPOSE

Randomized clinical trials have demonstrated the safety and efficacy of ocriplasmin in patients with vitreomacular traction (VMT), including those with macular hole (MH). The INJECT study prospectively evaluated ocriplasmin in the setting of clinical practice.

METHODS

INJECT was a Phase 4, multicenter, prospective observational study. Patients were followed up for 12 months. Assessments included nonsurgical VMT resolution, nonsurgical MH closure, best-corrected visual acuity, occurrence of vitrectomy, and adverse events.

RESULTS

The efficacy population (N = 395) received an ocriplasmin injection and had optical coherence tomography-confirmed VMT at baseline. At Day 28, the rate of nonsurgical VMT resolution was 40.7% in the overall group, and the rate of nonsurgical MH closure was 36.0% in the VMT with MH group. At Month 12, the rate of ≥2-line best-corrected visual acuity gain (irrespective of vitrectomy) was 36.8% in the overall group and 59.6% in the VMT with MH group. The percentage of patients who underwent vitrectomy in the study eye was 29.1% in the overall group and 55.6% in the VMT with MH group. Photopsia (9.8%) and vitreous floaters (6.8%) were the most frequent adverse events.

CONCLUSION

The INJECT study showed that ocriplasmin is effective in a clinical setting in patients with VMT, with or without MH. No new safety signals were identified from this large and surgeon-selected patient group, although the significant limitations of the study design without an image reading center and scheduled study visit timings should be noted.

Engineered microparticles and nanoparticles for fibrinolysis

Fibrinolytic agents including plasmin and plasminogen activators improve outcomes in acute ischemic stroke and thrombosis by recanalizing occluded vessels. In the decades since their introduction into clinical practice, several limitations of have been identified in terms of both efficacy and bleeding risk associated with these agents. Engineered nanoparticles and microparticles address some of these limitations by improving circulation time, reducing inhibition and degradation in circulation, accelerating recanalization, improving targeting to thrombotic occlusions, and reducing off-target effects; however, many particle-based approaches have only been used in preclinical studies to date. This review covers four advances in coupling fibrinolytic agents with engineered particles: (a) modifications of plasminogen activators with macromolecules, (b) encapsulation of plasminogen activators and plasmin in polymer and liposomal particles, (c) triggered release of encapsulated fibrinolytic agents and mechanical disruption of clots with ultrasound, and (d) enhancing targeting with magnetic particles and magnetic fields. Technical challenges for the translation of these approaches to the clinic are discussed.

Intravitreal ocriplasmin for the treatment of vitreomacular traction and macular hole- A study of efficacy and safety based on NICE guidance

Purpose

To evaluate the real world clinical outcomes of intravitreal ocriplasmin in patients with vitreomacular traction (VMT) with and without full thickness macular holes (FTMH) treated according to NICE guidance.

Methods

Retrospective observational case series of 25 patients treated with a single intravitreal ocriplasmin injection between December 2013 and December 2015. Best corrected visual acuity and optical coherence tomography exams were performed to determine visual outcomes and anatomical VMT release and FTMH closure over time. Two patient groups were identified: ocular macular co-morbidity (OCM) and no OCM (nOCM), with follow-up at 4, 12, and 24 weeks.

Results

Twenty-five patients were identified that included 19 patients with VMT, and 6 patients with VMT plus FTMH. In the nOCM group of 22 patients, the release rate of VMT was 44%, 63%, and 69% at 4, 12 and 24 weeks respectively. In the “real-world” OCM group of 25 patients, the VMT release rate was 37%, 53%, and 58% at the same time-points. In both groups, the FTMH closure rate was 33%, 50%, and 67% at 4, 12, and 24 weeks. At mean follow-up of 30 weeks in the VMT group with nOCM, the mean LogMAR VA improved significantly from 0.44 to 0.28 (p = 0.0068, paired t-test). Three were no serious adverse events.

Conclusions

This study reports improved efficacy of intravitreal ocriplasmin for both VMT and FTMH, and is more favourable in patients with no ocular co-morbidity. We highlight the importance of careful patient selection and structured standard of care pathways to identify patients who will benefit from the positive visual and anatomical effects of intravitreal ocriplasmin.

Long-Term Results of Vitrectomy for Macular Holes after Failure of Vitreolysis

PURPOSE

Ocriplasmin injection may close some small-to-medium macular holes associated with vitreoretinal traction. If the treatment fails, does vitrectomy and gas injection yield the same results as primary surgery?

MATERIAL AND METHODS

We report a retrospective case series study of 3 eyes of 3 consecutive patients operated on a few months after initial intravitreal injection of ocriplasmin and enlargement of the macular hole. The minimal follow-up period after surgery was 18 months.

RESULTS

Surgery was uneventful in all cases. Vitrectomy, internal limiting membrane peeling, and gas injection allowed closing of the 3 macular holes with a progressive improvement in visual acuity over time. Before ocriplasmin injection, visual acuity ranged from 20/60 to 20/32, after failed ocriplasmin injection from 20/80 to 20/40, and at the final follow-up after 18 months from 20/32 to 20/25.

CONCLUSION

Vitrectomy with internal limiting membrane peeling leads to closure of macular holes even in cases of prior failure to close them by ocriplasmin injection.

Ocriplasmin for symptomatic vitreomacular adhesion

BACKGROUND

Symptomatic vitreomacular adhesion (sVMA) is a recognised cause of visual loss and by tradition has been managed by pars plana vitrectomy (PPV). A less invasive alternative to surgery in some people is enzymatic vitreolysis, using an intravitreal injection of ocriplasmin.

OBJECTIVES

To assess the efficacy and safety of ocriplasmin compared to no treatment, sham or placebo for the treatment of sVMA.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2017, Issue 1), MEDLINE Ovid (1946 to 24 February 2017), Embase Ovid (1947 to 24 February 2017), PubMed (1946 to 24 February 2017), the ISRCTN registry (www.isrctn.com/editAdvancedSearch); searched 24 February 2017, ClinicalTrials.gov (www.clinicaltrials.gov); searched 24 February 2017 and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en); searched 24 February 2017. We did not use any date or language restrictions in the electronic searches for trials.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) of people with sVMA. The intervention was intravitreal ocriplasmin 125 μg injection, and this was compared to placebo or sham injection (control). Placebo was defined as a single intravitreal injection of 0.10 mL placebo with identical drug vehicle diluted with saline. A sham injection was defined as the syringe hub or blunt needle touching the conjunctiva to simulate an injection.

DATA COLLECTION AND ANALYSIS

Two authors independently selected relevant trials, assessed methodological quality and extracted data. We graded the certainty of the evidence using the GRADE approach.

MAIN RESULTS

This review included four RCTs conducted in Europe and the USA with a total of 932 eyes of 932 participants. Participants were 18 to 97 years of age, with evidence of focal vitreomacular adhesion (VMA) on optical coherence tomography (OCT) imaging, with a best corrected visual acuity (BCVA) of 20/25 or worse in the study eye and 20/400 or better in the fellow eye. The interventions compared were intravitreal ocriplasmin versus sham (two RCTs) or placebo (two RCTs) injection. Both sham and placebo injection were classified as the control group. The main outcome measures were assessed at 28 days and six months. Overall, we judged the studies to have a low or unclear risk of bias. All four RCTs were sponsored by the manufacturers of ocriplasmin.Compared with control, ocriplasmin treatment was more likely to result in VMA release within 28 days (risk ratio (RR) 3.46, 95% confidence interval (CI) 2.00 to 6.00; 859 eyes, 4 RCTs, high-certainty evidence). Approximately 97/1000 eyes will have VMA release within 28 days without treatment. An additional 237 eyes will have VMA release within 28 days for every 1000 eyes treated with ocriplasmin (95% CI 96 more to 482 more).Treatment with ocriplasmin was also more likely to result in macular hole closure (RR 2.87, 95% CI 1.50 to 5.51; 229 eyes, 3 RCTs, high-certainty evidence). Approximately 123/1000 eyes with macular holes will have closure with no treatment. An additional 231 eyes will have macular hole closure for every 1000 eyes treated with ocriplasmin (95% CI 62 more to 556 more).Eyes receiving ocriplasmin were also more likely to have complete posterior vitreous detachment (PVD) within 28 days (RR 2.94, 95% CI 1.39 to 6.24; 689 eyes, 3 RCTs, high-certainty evidence). Approximately 40/1000 eyes will have complete PVD within 28 days without treatment. An additional 78 eyes will have complete PVD within 28 days for every 1000 eyes treated with ocriplasmin (95% CI 16 more to 210 more).Eyes receiving ocriplasmin were more likely to achieve 3-line or greater improvement in BCVA at six months (RR 1.95, 95% CI 1.07 to 3.53; 674 eyes, 3 RCTs, moderate-certainty evidence). Approximately 61/1000 eyes will have a 3-line or greater improvement in BCVA at six months without treatment. An additional 58 eyes will have 3-line or greater improvement in BCVA at six months for every 1000 eyes treated with ocriplasmin (95% CI 9 more to 154 more).Receiving ocriplasmin also reduced the requirement for vitrectomy at six months (RR 0.67, 95% CI 0.50 to 0.91; 689 eyes, 3 RCTs, moderate-certainty evidence). Approximately 265/1000 eyes will require vitrectomy at six months without treatment and 87 fewer eyes will require vitrectomy for every 1000 eyes treated with ocriplasmin (95% CI 24 fewer to 132 fewer).Treatment with ocriplasmin resulted in a greater improvement in validated Visual Function Questionnaire form score at six months (mean improvement difference 2.7 points, 95% CI 0.8 to 4.6; 652 eyes, 2 RCTs, moderate-certainty evidence).Eyes receiving ocriplasmin were more likely to have an adverse event (RR 1.22, 95% CI 1.09 to 1.37, 909 eyes, 4 RCTs, moderate-certainty evidence). Approximately 571/1000 eyes will have an adverse event with sham or placebo injection and 106 more eyes will have an adverse event for every 1000 eyes treated with ocriplasmin (95% CI 52 more to 212 more).

AUTHORS' CONCLUSIONS

Evidence from a limited number of RCTs suggests that ocriplasmin is useful in the treatment of sVMA. However, up to 20% of eyes treated with ocriplasmin will still require additional treatment with PPV within six months. There were more ocular adverse events in eyes treated with ocriplasmin than control (sham or placebo injection) treatment. Many of these adverse events, particularly vitreous floaters and photopsia, are known to be associated with posterior vitreous detachment. At present however, there is minimal published long-term safety data on eyes treated with ocriplasmin. Further large RCTs comparing ocriplasmin with other management options for sVMA would be beneficial.

Assessment of intravitreal ocriplasmin treatment for vitreomacular traction in clinical practice

PURPOSE

To assess treatment effects following intravitreal injection of ocriplasmin for vitreomacular traction (VMT), with or without full-thickness macular hole (FTMH), in real-life setting.

METHODS

This is a monocentric, retrospective, consecutive series of 82 eyes from 82 patients who underwent ocriplasmin treatment between July 2013 and December 2016. We included 57 eyes with pure VMT, 17 eyes with small FTMHs, and eight eyes with medium FTMHs. Primary outcome measures were VMT release and MH closure rates. Secondary outcomes were visual acuity (VA), morphological changes, and subjective visual impairment after 1, 3, and 6 months and at last follow-up.

RESULTS

After a median follow-up of 10 months, VMT release was achieved by pharmacologic vitreolysis in 57% of all eyes, whereas the macular hole closure rate was 32%. In those presenting with five or more positive prognostic factors (PPF), eyes with pure VMT showed nonsurgical traction release in 88%, and FTMHs were released in 93%, with a closure rate of 20%. Small FTMHs closed in 41% and medium FTMHs in 13%. The mean change in VA (LogMAR) was -0.07 ± 0.24 (median - 0.10) in all eyes. Subretinal fluid accumulation and ellipsoid zone changes were seen in 31% and 37% of all eyes, respectively. They were more frequent in eyes with traction release, but were self-limited.

CONCLUSIONS

In a real-life setting, release of VMT by ocriplasmin injection can be achieved in the majority of eyes, relying on a strict patient selection. Closure of FTMHs rather correlates with hole diameter than with presence of PPF, and remains a rare finding in medium FTMHs.

Baseline Predictors of Vitreomacular Adhesion/Traction Resolution Following an Intravitreal Injection of Ocriplasmin

BACKGROUND AND OBJECTIVE

To determine factors predicting response to ocriplasmin (Jetrea; ThromboGenics, Iselin, NJ) response in patients with symptomatic vitreomacular adhesion (VMA).

PATIENTS AND METHODS

Combined analysis of two multicenter, prospective, randomized, double-masked trials of intravitreal ocriplasmin 125 µg injection versus placebo. Patients had vitreomacular traction with or without a full-thickness macular hole (FTMH). Multivariate logistic regression was used to determine factors influencing treatment response (complete VMA release [day 28] and non-surgical FTMH closure [month 6]).

RESULTS

Younger age, presence of FTMH (odds ratio [OR] = 2.1; 95% confidence interval [CI], 1.1-3.7), VMA diameter of 1,500 µm or less (OR = 4.9; 95% CI, 2.0-12.4), phakic lens status (OR = 2.8; 95% CI, 1.5-5.2), and absence of epiretinal membrane (OR = 4.1; 95% CI, 2.2-7.9) predicted VMA resolution. FTMHs with apical diameter of 250 µm or less were more likely to close than larger holes (58.3% vs. 24.6%; P = .013). Both FTMH size groups had significantly greater chance of VMA resolution and FTMH closure versus controls.

CONCLUSION

Ocriplasmin is most effective in younger patients with focal VMA and without an epiretinal membrane. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:716-723.].

ELLIPSOID ZONE MAPPING AND OUTER RETINAL CHARACTERIZATION AFTER INTRAVITREAL OCRIPLASMIN

PURPOSE

To assess outer retinal architectural alterations after intravitreal ocriplasmin with a novel automated ellipsoid zone (EZ) mapping algorithm.

METHODS

A single-center, retrospective, consecutive case series of image analysis was performed. Quantitative assessment of EZ status imaged with spectral-domain optical coherence tomography was performed before and after single intravitreal injection of 0.125 mg of ocriplasmin (Jetrea, Thrombogenics). A novel EZ mapping algorithm was used to assess the EZ retinal pigment epithelium (RPE) central area, EZ-RPE macular volume, and en face EZ integrity based on the percentage of sampling areas with 20 μm or greater EZ-RPE thickness. Longitudinal assessment of these changes with custom optical coherence tomography reading software was completed. Clinical characteristics and outcomes were compared with these retinal changes.

RESULTS

Nineteen eyes were included in this study. The retinal volume between EZ and RPE was significantly reduced at 1 week after ocriplasmin (P = 0.0036). Seven of 19 patients (36.8%) complained of color abnormalities or brightness reduction after injection. All of these seven patients had increased subretinal fluid after ocriplasmin and EZ attenuation. The EZ-RPE volume was reduced at 1 week (P = 0.0036), 1 month (P = 0.015) after ocriplasmin, and restored by 3 months. The area with EZ-RPE thickness below 20 μm was increased at 1 week (P = 0.046) after ocriplasmin and recovered with time.

CONCLUSION

Mapping of EZ is feasible to assess EZ-RPE volume and overall EZ integrity with en face thickness mapping. Alterations in EZ occur in a significant proportion of eyes after ocriplasmin therapy. The EZ-RPE volume and the EZ-RPE central foveal area typically recover to baseline by 3 months. This effect appears to be panretinal and associated with subjective symptoms.

Results of the 2-Year Ocriplasmin for Treatment for Symptomatic Vitreomacular Adhesion Including Macular Hole (OASIS) Randomized Trial

PURPOSE

The Ocriplasmin for Treatment for Symptomatic Vitreomacular Adhesion Including Macular Hole (OASIS) trial was designed to evaluate the long-term efficacy and safety profile of ocriplasmin for the treatment of symptomatic vitreomacular adhesion (VMA)/vitreomacular traction, including full-thickness macular hole (FTMH).

DESIGN

Phase 3b, randomized, sham-controlled, double-masked, multicenter clinical trial.

PARTICIPANTS

Sample size was 220 subjects (146 ocriplasmin, 74 sham) randomized in a 2:1 ratio to receive intravitreal ocriplasmin 0.125 mg or sham injection.

METHODS

The trial involved 12 visits over 24-months. Inclusion criteria included presence of VMA and best-corrected visual acuity (BCVA) of 20/32 or worse in the study eye. Exclusion criteria included FTMH >400 μm, presence of epiretinal membrane (ERM), and aphakia in the study eye.

MAIN OUTCOME MEASURES

The primary efficacy end point was the proportion of subjects with pharmacologic VMA resolution at day 28. Secondary efficacy end points were assessed at month 24 and included proportion of subjects with BCVA gain from baseline, nonsurgical FTMH closure, vitrectomy, and Visual Function Questionnaire 25 (VFQ-25) outcomes.

RESULTS

The OASIS trial met its primary end point with pharmacologic VMA resolution at day 28 being significantly higher in the ocriplasmin group (41.7%) compared with the sham group (6.2%). The treatment effect was maintained until study end. In the ocriplasmin group, pharmacologic VMA resolution at day 28 was higher in subgroups with the following baseline characteristics compared with the complementary subgroups without them: presence of focal VMA, presence of FTMH, absence of ERM, and phakic lens status. In the ocriplasmin group, 50.5% of subjects had a ≥2-line improvement in BCVA from baseline compared with 39.1% of subjects in the sham group. The nonsurgical FTMH closure rate was 30.0% for the ocriplasmin group compared with 15.4% for the sham group. All other secondary end points also favored ocriplasmin over sham. Regarding safety, most adverse events were mild to moderate, had a short onset time, and were transient, with no new safety signals identified.

CONCLUSIONS

The OASIS trial demonstrates the long-term efficacy and safety of ocriplasmin, providing improved resolution of symptomatic VMA compared with previous phase 3 trials with no additional safety signals identified.

Review of economic studies and budget impact analysis of ocriplasmin as a treatment of vitreomacular traction

OBJECTIVE

To review the evidence on the cost-effectiveness of ocriplasmin as a treatment for vitreomacular traction (VMT), and to estimate the impact on the Spanish National Health System (NHS).

MATERIAL AND METHODS

1) Systematic review. The following databases were searched in January 2015: MEDLINE, PREMEDLINE, EMBASE, CRD, the Cochrane Library, and key websites. Selection criteria were: full economic evaluations that compared ocriplasmin with usual care ('watch and wait' and/or vitrectomy) in patients with VMT. The outcomes to extract were costs of the alternatives and the incremental cost-effectiveness ratio. Studies of budget impact analysis were also included. The methodological quality was assessed, and a narrative synthesis of the included studies was carried out. 2) Estimation of budget impact. The impact on the budget as a result of the introduction of ocriplasmin in the NHS was estimated, including data from different sources.

RESULTS

Six studies were identified, none of them performed in Spain. The two best studies concluded that ocriplasmin is cost-effective in their respective countries (Canada and United Kingdom), but only in patients with certain conditions (without epiretinal membrane, for example). The results of the budget impact analysis are different between countries. The analysis for Spain showed that the introduction of ocriplasmin would mean a saving over 1 million Euros for the NHS in 5 years.

CONCLUSIONS

The cost-effectiveness of ocriplasmin has not been demonstrated in Spain. However, good studies performed in other countries found that ocriplasmin is cost-effective in selected patients. Given the current prices in Spain, ocriplasmin could involve a saving for the Spanish NHS.

Rare Association of Klippel-Trenaunay Syndrome with Large Pulmonary Embolism and Asymmetrical Emphysematous Bullae

Klippel-Trenaunay syndrome is a rarely encountered congenital disease characterized by a triad of enlarged arteries and veins, limb hypertrophy and capillary malformations. We are presenting an interesting case of a 23-year male who had been previously diagnosed to have Klippel-Trenaunay syndrome. The patient presented with large pulmonary embolism after having undergone laser surgery for varicose veins. The diagnostic chest computed tomography (CT) performed also revealed the co-existence of severe destructive pulmonary parenchymal disease involving large areas of the pulmonary parenchyma and formation of large emphysematous bullae having an asymmetric involvement of the left lung field. The patient was managed with thrombolysis with a bolus fibrinolytic agent and subsequently underwent an inferior vena cava (IVC) filter implantation to prevent further episodes of embolism in the presence of a compromised lung. The association of Klippel-Trenaunay syndrome with recurrent pulmonary embolism and unexplained pulmonary parenchymal disease leading to almost complete destruction of large areas of lung fields is interesting and has never been previously described.

Treatment outcomes and spectral-domain optical coherence tomography findings of eyes with symptomatic vitreomacular adhesion treated with intravitreal ocriplasmin

PURPOSE

To determine treatment outcomes of intravitreal ocriplasmin in symptomatic vitreomacular adhesion.

DESIGN

Retrospective interventional case series.

METHODS

setting: Private practice. study population: Thirty-five eyes (35 subjects) with symptomatic vitreomacular adhesion. intervention/observation: Intravitreal ocriplasmin injection from February to November 2013. main outcome measure: Vitreomacular adhesion resolution rate. Secondary endpoints included postinjection visual acuity and rates of outer retinal attenuation and full-thickness macular hole (MH) closure.

RESULTS

The 35 subjects included were of mean age 69 years, 66% female, and 71% phakic. Eleven subjects (31%) had macular comorbidities. Average adhesion diameter was 571 μm, with mean 7.9 months duration of symptoms. Nine subjects (26%) had epiretinal membrane and 6 (17%) had MH (mean diameter 186 μm). Mean preinjection logarithm of the minimal angle of resolution visual acuity was 0.46, and improved to 0.33 at final follow-up. Fifteen eyes (43%) achieved adhesion release at mean 10 days post injection. One of 6 MH (17%) closed. Transient outer retinal attenuation occurred in 10 of 35 cases (29%), with 8 of 10 (80%) achieving adhesion release. One subject (3%) developed a retinal detachment. Adhesion resolution was more likely in patients with younger age (P = .04), absence of comorbidities (P = .02), small adhesion diameter (P = .005), short adhesion duration (P = .03), and transient outer retinal attenuation (P = .008).

CONCLUSIONS

Intravitreal ocriplasmin efficacy in the private practice setting, while including patients with macular comorbidities, is similar to that of previous studies. Transient toxicity to the outer retina occurs frequently-typically with adhesion resolution-necessitating careful postinjection spectral-domain optical coherence tomography monitoring.

Acute vision loss after ocriplasmin use

PURPOSE

There have been reports in the literature of transient vision loss after ocriplasmin injection and ellipsoid layer disruption on spectral domain optical coherence tomography. The authors report a patient with transient vision loss and more prolonged ellipsoid layer dysfunction.

PATIENT

The authors present a 55-year-old woman with vitreomacular traction and a small foveal schisis who received ocriplasmin injection and experienced sudden transient vision loss. Spectral domain optical coherence tomography imaging revealed significantly increased schisis, new subretinal cavity, and prolonged ellipsoid layer disruption at 9 months.

DISCUSSION

Previous reports suggested that acute vision loss after ocriplasmin injection may be due to ellipsoid layer disruption. This case showed vision loss, which may due to increased foveal schisis and a new subretinal cavity on spectral domain optical coherence tomography imaging. There was little correlation between ellipsoid layer loss and visual function.

[Research update of ocriplasmin for symptomatic vitreomacular adhesion]

Ocriplasmin is a recombinant truncated form of human serine protease plasmin with proteolytic activity to induce vitreous liquefaction and weaken vitreomacular adhesion, thereby facilitating posterior vitreous detachment and acting as a potential alternative to replace the more traumatic vitrectomy which can result in incomplete vitreoretinal separation. Intravitreal ocriplasmin for symptomatic vitreomacular adhesion has been systematically evaluated in clinical trials. Ocriplasmin at the recommended dose of a single 125 µg intravitreal injection has recently been approved for the treatment of symptomatic VMA in the USA and EU. This review is aiming to highlight the research update of ocriplasmin.

Bilateral vitreomacular traction resolved with a single intravitreal ocriplasmin injection

A 74-year-old woman was referred by her ophthalmologist for evaluation of blurred vision in both eyes over the course of several months, presenting with a best corrected visual acuity (BCVA) of 20/150 in the right eye and 20/50 in the left eye. Optical coherence tomography showed vitreomacular traction (VMT) bilaterally with a full-thickness macular hole in the right eye; a single intravitreal injection of 125 μg ocriplasmin was administered in the right eye. One week after the injection, BCVA in the right eye improved to 20/60 with release of VMT, and at 3 weeks bilateral release of VMT was observed.

[Progression of pharmacologic vitreolysis research]

It is now well recognized that vitreomacular adhesion (VMA) plays an important role in the pathogenesis of various retinopathy. Traction released through pars plana vitrectomy was used before, but it is limited by some problems such as incomplete vitreoretinal separation, vitreous remnant and other operative complications. While another new method-Pharmacologic Vitreolysis provided us a new method for persistent pathologic VMA treatment. This review aims to introduce the vitreous molecular structure, principles of posterior vitreous detachment and progression of pharmacologic vitreolysis method study.

Catheter-directed thrombolysis with microplasmin for acute peripheral arterial occlusion (PAO): an exploratory study

AIM

We performed an open-label, dose-ascending, single-centre, Phase IIa study to explore the safety and efficacy of catheter-directed thrombolysis (CDT) with microplasmin for infrainguinal arterial or bypass occlusions.

METHODS

Patients who presented with acute occlusions were subsequently treated with an intrathrombus infusion of five ascending doses of microplasmin: 0.3 mg/kg/h for 4 hours; 0.45 mg/kg/h for 4 hours; 0.6 mg/kg/h for 4 hours; 0.9 mg/kg/h for 4 hours or 0.6 mg/kg/h for 6 hours. Repeat angiograms were obtained to assess the degree of clot lysis. The primary outcome was complete thrombolysis defined as >95% thrombus volume reduction at the end of the microplasmin infusion. Safety evaluation included bleedings, adverse events and coagulation biomarkers.

RESULTS

Complete thrombolysis was obtained in 3 of the 19 treated patients at the end of microplasmin infusion. Thrombus volume reduction between 50% and 95% was achieved with all dosing regimens. Clinically significant distal embolization occurred in 8 patients. One major and two non-major bleedings occurred. Microplasmin depleted α2-anti-plasmin and decreased fibrinogen.

CONCLUSION

Intrathrombus infusion of microplasmin for 4 or 6 hours resulted in significant clot lysis. Distal embolization appeared the most important limitation.

Safety of catheter-delivered plasmin in patients with acute lower extremity arterial or bypass graft occlusion: phase I results

BACKGROUND

Current treatment of acute peripheral artery or bypass graft occlusion utilizes catheter-directed thrombolysis of a plasminogen activator (PA). Plasmin is a direct-acting thrombolytic with a striking safety advantage over PA in preclinical models.

OBJECTIVES

To report the first use of purified plasmin for acute lower extremity arterial or bypass graft thrombosis in a phase I dose-escalation study of a catheter-delivered agent.

METHODS

Eighty-three patients with non-embolic occlusion of infrainguinal native arteries or bypass grafts were enrolled (safety population) into seven sequential dose cohorts to receive 25-175 mg of plasmin by intrathrombus infusion over 5 h. Arteriograms were performed at baseline, 2 h, and 5 h, and subjects were monitored for 30 days for clinical outcomes and laboratory parameters of systemic fibrinolysis.

RESULTS

Major bleeding occurred in four patients (4.8%), and minor bleeding alone in 13 (15.7%), with no trend towards more bleeding at higher dosages of plasmin. There was a trend towards lower plasma concentrations of fibrinogen, α(2) -antiplasmin and α(2) -macroglobulin with increasing doses of plasmin, but the nadir fibrinogen concentration was > 350 mg dL(-1) at the highest plasmin dose. Individual nadir values were above 200 mg dL(-1) in 82 of 83 subjects, and were not different in patients with or without bleeding. Thrombolysis (≥ 50%) occurred in 79% of subjects receiving 125-175 mg of plasmin, as compared with 50% who received 25-100 mg.

CONCLUSIONS

Catheter-delivered plasmin can be safely administered to patients with acute lower extremity arterial occlusion at dosages of 25-175 mg.

[The research of thrombolytic and hemolysis effect from Eupolyphage fibrinolyric protein and its inhibitory effect on S180 ascites tumor of mice]

OBJECTIVE

Eupolyphage fibrinolyric protein (EFP) was isolated and purified from Eupolyphage sineses, and its thrombolytic effect, hemolysis effect and inhibitory effect on S180 ascites tumor were investigated.

METHODS

EFP was isolated and purified by ammonium precipitation and DEAE ion exchange chromatography. It's thrombolytic and hemolysis effect were determined. MTT method and Colony-forming method were used to determine the inhibitory effect on S180 ascites tumor.

RESULTS

the EFP was proved to have the effect of Thrombolytic and Hemolysis, and both increased dose-dependently, however at a lower concentration, the EFP had no hemocytolysis. The EFP was also proved the effect of inhibitory on cell proliferation and Colony-forming on S180 ascites tumor of Mice.

CONCLUSION

EFP has a strong thrombolytic activity and weak hemolytic, and has inhibitory effect on S180 ascites tumor of mice.

Pharmacologic vitreodynamics and molecular flux

Several enzymatic agents, such as autologous plasmin enzyme and recombinant microplasmin, are able to cause vitreous liquefaction and a complete posterior vitreous detachment (PVD). Advancements in research have helped to explain the complex interactions that occur in the vitreous cavity after a PVD is created. The development of a PVD is a dynamic process that is thought to have a larger impact on the vitreous cavity milieu than just a separation of the posterior cortical vitreous from the retina. Pharmacologic vitreodynamics attempts to explain the mechanical and biochemical changes that occur at the vitreoretinal junction after a PVD is formed. The flow of molecules into and out of the vitreous cavity and across the vitreoretinal junction is thought to be influenced by the presence or absence of a PVD. A microplasmin-induced PVD has been shown to alter the vitreous levels of several molecules, and a PVD may have a protective role in multiple diseases. Significant progress has been made in the field of pharmacologic vitreodynamics. As we improve our understanding of the molecular flux in the vitreous cavity, pharmacologic vitreodynamics will likely become more important as it may allow for improved manipulation of intravitreal molecules.

Objective of pharmacologic vitreolysis

The goal of pharmacologic vitreolysis is to cleave the vitreoretinal junction, thereby inducing posterior vitreous detachment (PVD), and to liquefy the vitreous gel. There are several reasons to pursue a pharmacologic approach: (1) Mechanical vitrectomy is incomplete. Both at the posterior pole and in the retinal periphery, remnants of the cortical vitreous are left behind at the internal limiting membrane of the retina, causing vitreoretinal traction and (re)proliferation of cells, and leading to surgical failure. (2) Pharmacologic vitreolysis offers complete PVD without mechanical manipulation at the vitreoretinal interface, such as ILM peeling, thereby minimizing the risk of iatrogenic damage to the macula. (3) An intravitreal injection resulting in complete PVD is a less traumatic approach than vitrectomy, and it might be beneficial as prophylactic treatment regime in retinal diseases characterized by fibrocellular and fibrovascular proliferation at the vitreoretinal interface, such as diabetic macular edema and proliferative retinopathy, in order to prevent advanced stages of disease. (4) Cleaving the cortical hyaloid completely from the retina changes the molecular flux across the vitreoretinal interface and improves oxygen supply to the retina, a major mechanism of action which might significantly interfere with biochemical pathways of retinal hypoxia, leading to an overexpression of vasoactive substances such as vascular endothelial growth factor.

Microplasmin-assisted vitrectomy

Microplasmin (Thrombogenics Ltd., Leuven, Belgium) is a recombinant molecule consisting of the catalytic domain of human plasmin. It is highly characterized, and supplied in a stabilized form, simplifying storage and administration. Microplasmin shares the same catalytic properties like human plasmin, but it is much more stable compared to plasmin. It has been shown previously that both plasmin and microplasmin are capable of inducing PVD. This chapter focuses on one of the most promising current concepts of pharmacologic vitreolysis, i.e. microplasmin-assisted vitrectomy. We report on the preclinical work of plasmin and microplasmin which lead to the clinical investigation of microplasmin in different clinical trials, the so-called MIVI trials.

A first-in-human phase I trial of locally delivered human plasmin for hemodialysis graft occlusion

BACKGROUND

Hemodialysis (HD) grafts often fail because of stenosis at the venous anastomosis and thrombotic occlusion. Percutaneous management relies on thrombolysis with plasminogen activators, mechanical removal of thrombus, and angioplasty of the stenotic lesion.

OBJECTIVES

This report describes a phase I trial using Plasmin (Human) TAL 05-00018, a direct-acting fibrinolytic agent, to evaluate safety and, secondarily, to establish effective thrombolytic dosing.

PATIENTS/METHODS

Six cohorts of five patients with acute HD graft occlusion documented by angiography were treated with escalating dosages of plasmin (1, 2, 4, 8, 12, and 24 mg) infused over 30 min via criss-crossed pulse-spray catheters within the graft. The primary efficacy endpoint was > or =50% thrombolysis, as determined by comparison of pre-plasmin and 30-min post-plasmin fistulograms.

RESULTS

Of 31 subjects who received study drug (safety population), one withdrew and 30 completed the trial (evaluable for efficacy). There was no significant change in plasma alpha-2 antiplasmin or fibrinogen concentration, major bleeding did not occur, and there were no deaths. Serious adverse events in four patients were not related to the study drug. There was a dose-response relationship for the primary efficacy endpoint, all five subjects receiving 24 mg achieving >75% lysis.

CONCLUSIONS

This first phase I study of Plasmin (Human) TAL 05-00018, infused into thrombosed HD grafts, documents safety at dosages of 1-24 mg and an effective thrombolytic dosage of 24 mg. The results establish a foundation for further clinical study of catheter-based plasmin administration in thrombotic disorders.

[Comprehensive prophylaxis for deep venous thrombosis after proximal femur fractures in geriatric patients]

OBJECTIVE

To evaluate the efficacy and safety of comprehensive prophylaxis for deep venous thrombosis (DVT) after proximal femur fractures in geriatric patients.

METHODS

From July 2003 to May 2006, 157 geriatric patients with proximal femur fractures treated with operation were divided into prophylaxis group and control group randomly. There were 82 patients (34 males, 48 females, aged 65-97 years) in prophylaxis group, 30 with femoral neck fracture and 52 with intertrochanteric fracture of femur. There were 75 patients (33 males, 42 females, aged 65-94 years) in control group, 28 with femoral neck fracture and 47 with intertrochanteric fracture of femur. In the prophylaxis group, comprehensive prophylaxis for DVT which included Aspirin, fibrinolytic enzyme, passive and active circumduction of the foot and ankle, CPM management was applied. In the control group, no thromboproxylaxis was taken. All patients in the both groups received color doppler flow imaging (CDFI) examination before operation and on the 7thand 14th days after operation.

RESULTS

CDFI found 2 cases of DVT in the prophylaxis group 7 and 14 days after operation respectively, while 21 and 15 cases of DVT in the control group respectively. The incidence of DVT was 48.0% in the control group compared with 4.9% in the prophylaxis group and the reduction was significant (P < 0.01). One patient gave up the intervention due to Melena 3 days after operation in the prophylaxis group. In the control group, 1 patient died 8 days after operation and another died 11 days after operation. Both died of acute pulmonary embolism confirmed by autopsy.

CONCLUSION

The comprehensive prophylaxis can significantly decrease the incidence of DVT in geriatric patients after proximal femur fractures. There is no significant adverse effect during the intervention.

Autologous plasmin-assisted vitrectomy for stage 5 retinopathy of prematurity: a preliminary trial

PURPOSE

To evaluate the efficacy of autologous plasmin (AP)-assisted vitrectomy for stage 5 retinopathy of prematurity (ROP).

DESIGN

Interventional case series.

METHODS

Six consecutive eyes of four children with stage 5 ROP were treated. The patients' ages at the surgery ranged from five to eight months after birth. Four eyes showed closed-closed configuration and two eyes showed open-open configuration. After lensectomy and dissection of the anterior proliferative membrane, 0.03 to 0.22 International Unit (IU) of AP was administrated into the vitreous cavity. After 15 to 30 minutes of incubation, the proliferative membrane was treated.

RESULTS

The proliferative membrane was removed successfully without iatrogenic retinal break. Complete reattachment of the posterior pole retina was achieved in all six eyes (100%). No obvious complication was observed in the follow-up period, which ranged from 11 to 14 months.

CONCLUSIONS

These results suggest the benefit of AP in the vitrectomy for treatment of stage 5 ROP.

Pharmacologic vitreolysis

At present, surgical separation of the vitreous from the retina (posterior vitreous detachment, PVD) is achieved by mechanical means only. However, with this technique, complete removal of the cortical vitreous from the internal limiting membrane of the retina is not feasible. As incomplete PVD and an attached vitreous cortex are associated with the progression of common retinal diseases including diabetic retinopathy and maculopathy, central retinal vein occlusion and proliferative vitreoretinopathy, induction of complete PVD is a major issue both in vitreoretinal surgery and in medical retina. This chapter focuses on current concepts of pharmacologic vitreolysis. Agents capable of altering the molecular organization of the vitreous are introduced and discussed in terms of PVD induction and liquefaction of the vitreous gel.

Use of autologous plasmin during vitrectomy for diabetic maculopathy

PURPOSE

To evaluate the efficacy of autologous plasmin enzyme as an adjunct to vitrectomy in diabetic macular edema.

METHODS

Plasmin derived from autologous blood was injected intravitreally into seven eyes 15 min before vitreous surgery. The development and progression of a posterior vitreous detachment (PVD) was followed, and the time required for vitreous removal was measured. Both pre- and postoperative visual acuities and optical coherence tomography (OCT)-determined macular thickness were measured.

RESULTS

In the seven eyes in which plasmin was used, a PVD developed approximately 5 min after the injection and was confirmed to extend to the far periphery. In all cases, the removal of the vitreous was completed in a shorter time and no complications were observed. A restoration of the shape of the macula was observed in all cases. The visual acuity improved by two or more lines in four eyes, and remained unchanged in the remaining three eyes.

CONCLUSIONS

Autologous plasmin alone will create a full PVD, and eliminates the need for a mechanical creation of a PVD. Thus, plasmin is a safe and effective adjunct to vitreous surgery for the treatment of diabetic maculopathy.

Causes and treatment of vitreous hemorrhage

Vitreous hemorrhage is common, with varied clinical manifestations and causes. The most common causes include proliferative diabetic retinopathy, vitreous detachment with or without retinal breaks, and trauma. Less common causes include vascular occlusive disease, retinal arterial macroaneurysm, hemoglobinopathies, age-related macular degeneration, intraocular tumors, and others. The natural history depends on the underlying cause, and is generally more favorable in eyes without underlying disease. Treatment is directed at the underlying cause, such as laser photo-coagulation for proliferative diabetic retinopathy or for retinal breaks. Occasionally, hemorrhage does not resolve spontaneously and vitrectomy surgery is necessary and beneficial. New strategies for the treatment of vitreous hemorrhage, such as pharmacologic vitreous liquefaction, may be important in the future.

Effects of plasmin on sperm-oocyte interactions during in vitro fertilization in the pig

The present study was undertaken to examine the effect of plasmin on sperm viability and sperm-oocyte interaction during in vitro fertilization in the pig. Porcine sperm, which were washed in Dulbecco's PBS were re-suspended and incubated in fertilization medium (mTBM; modified Tris-buffered medium) containing 0, 0.1, 1.0, 10.0 or 100.0ng/mL of plasmin. Sperm viability was not affected by plasmin treatment. Addition of plasmin in doses ranging from 0.1 to 100.0ng/mL for 2, 4 or 6h to washed boar sperm resulted in enhancement of acrosome reaction (AR) compared with untreated cells. The concentration of 0.1ng/mL plasmin (95+/-18 sperm/oocyte) had no effect on sperm binding, whereas 1.0ng/mL (123+/-21 sperm/oocyte), 10.0ng/mL (124+/-16 sperm/oocyte) and 100.0ng/mL (124+/-15 sperm/oocyte) of plasmin increased sperm binding compared with the control (83+/-15 sperm/oocyte). The zona pellucida solubility (zona dissolution time) was less in medium with 1.0ng/mL (123+/-24s), 10.0ng/mL (99+/-15s) or 100.0ng/mL (95+/-19s) plasmin compared with control (176+/-27s). When pig oocytes and sperm were co-incubated in various concentrations of plasmin for 6h, the penetration rate was greater in medium with 1.0ng/mL plasmin (77.5+/-3.1%) compared with the control. However, there were no differences in the polyspermic rates and mean number of sperm (MNS)/oocyte between the groups treated with plasmin and control. These results suggest that plasmin might play a role in events related to fertilization.

Efficacy of autologous plasmin for idiopathic macular hole surgery

PURPOSE

To determine whether a single intravitreal injection of autologous plasmin or a combination of plasmin and intraocular gas without peeling the internal limiting membrane (ILM) will close idiopathic macular holes.

METHODS

Eight eyes of seven patients with an idiopathic macular hole were studied. The degree of posterior vitreous detachment (PVD), vitreal liquefaction, closure of the macular hole, visual acuity, and complications following intravitreal plasmin or plasmin with gas were investigated. The removed ILM was examined by electron microscopy.

RESULTS

A PVD was created in seven out of eight eyes exposed to plasmin or plasmin with gas, however, the macular hole was not closed by either. Closure occurred in two eyes using conventional vitrectomy after the plasmin with gas injection, but peeling the ILM was required in the remaining six eyes. Vitreal fibers and glial cells were not observed on the vitreal surface of the extracted ILM.

CONCLUSIONS

A PVD was created safely and reliably although closure of the macular hole did not occur with either plasmin or with plasmin and gas injection. However, vitreous surgery became easier, and it required a shorter time to close the macular hole with intravitreal plasmin.

Mechanismen zur Beeinflussung der Zellphysiologie als Wundheilungskonzept

AIM

Recent knowledge about repair mechanisms in different types of tissue is the basic of actual therapeutic efforts. Center of several experimental and clinical approaches is the influencing of angiogenesis with an also distinct meaning concerning wound healing. Therefore, application of growth factors, gene transfer, and employment of genetically manipulated cells often aim at angiogenesis. Nevertheless, manipulation of angiogenesis also leads to secondary problems such as hyperpermeability followed by impairment of local wound milieu. Our study was done to identify mechanisms to protect from disturbances of endothelial barrier function.

METHOD

In a first experimental investigation on cultured endothelial cells, the influence of plasma-transglutaminase (Factor XIII) to endothelial barrier function was studied. In a second step, the influence of Factor XIII on wound healing properties was investigated in patients with a chronic venous ulceration.

RESULTS

Activated Factor XIII (FXIIIA*) led to a dose-dependent reduction of endothelial cell permeability of 30 % compared to control with a maximum effect using 1 to 5 U/mL. Clinical investigation revealed a nearly complete reduction of wound secretion.

CONCLUSION

Experimental studies revealed that activated Factor XIII stabilizes endothelial barrier under basic conditions as well as under conditions of induced hyperpermeability. Clinical study revealed that Factor XIII also distinctly reduces wound secretion. Therefore, plasma-transglutaminase may offer a new therapeutic option to treat the local or generalized leakage-syndrome.

Intravitreal plasmin injection activates endogenous matrix metalloproteinase-2 in rabbit and human vitreous

PURPOSE

To investigate the effect of exogenous plasmin administration on the activity of endogenous matrix metalloproteinase-2 (MMP-2) in rabbit and human vitreous.

DESIGN

Experimental animal study and interventional case series.

METHODS

Human plasmin was injected into rabbit eyes. The active/pro-MMP-2 ratio in vitreous samples was calculated using the gelatin zymography. Scanning electron microscopy (SEM) was performed to observe the retinal surface. To evaluate the time course of MMP-2 activity, vitreous samples were collected after the injection of 0.5 IU of plasmin, and the active/pro-MMP-2 ratio was calculated in the same manner. Immunohistochemical analysis was performed to confirm the presence of MT1-MMP in the rabbit eye. Human vitreous samples obtained from vitreous surgeries were also used for similar studies.

RESULTS

The active/pro-MMP-2 ratios in the vitreous after the injection of 0.25 IU or 0.5 IU of plasmin were significantly higher than that of the control (P < .05). SEM demonstrated that plasmin-treated eyes showed a smooth retinal surface that was dose-dependent. Time course evaluation of the active/pro-MMP-2 ratio in the vitreous after the administration of 0.5 IU of plasmin found a significant difference between the 5 and 15 minutes data points compared with that seen for the control. Immunohistochemical study revealed the presence of MT1-MMP in the inner retina. In human samples, the active/pro-MMP-2 ratio after the plasmin injection was significantly higher than the ratio observed before injection.

CONCLUSIONS

Our results suggested that activation of endogenous MMP-2 by exogenous plasmin is associated with the induction of posterior vitreous detachment.

Modification by the tissue plasminogen activator-plasmin system of morphine-induced dopamine release and hyperlocomotion, but not anti-nociceptive effect in mice

The extracellular serine protease tissue plasminogen activator (tPA) that converts plasminogen into plasmin is abundantly expressed throughout the central nervous system. We have recently demonstrated that the tPA-plasmin system participates in the rewarding and locomotor-stimulating effects of morphine by acutely regulating morphine-induced dopamine release in the nucleus accumbens (NAc). In the present study, we examined the effects of microinjections of plasminogen activator inhibitor-1 (PAI-1), tPA or plasmin into the NAc on morphine-induced dopamine release, hyperlocomotion and anti-nociceptive effects in ICR mice. A single morphine treatment resulted in an increase in protein levels of PAI-1 in the NAc. Microinjection of PAI-1 into the NAc dose-dependently reduced morphine-induced dopamine release and hyperlocomotion. In contrast, microinjection of tPA into the NAc significantly potentiated morphine-induced dopamine release and hyperlocomotion without affecting basal levels. Furthermore, microinjection of plasmin enhanced morphine-induced dopamine release, but did not modify the hyperlocomotion induced by morphine. The intracerebroventricular injection of PAI-1, tPA and plasmin at high doses had no effect on the anti-nociceptive effects of morphine. These results suggest that the tPA-plasmin system is involved in the regulation of morphine-induced dopamine release and dopamine-dependent behaviors but not the anti-nociceptive effects of morphine.

[Treatment of bedsores--combination of therapies depended the experimental design method]

The treatment of bedsores is a particular problem in geriatric medicine. We selected standard drugs that may be effective for the decubitus ulcer, and investigated combination therapy to develop efficient treatment The subjects were 16 patients in whom the grade of the bedsore was evaluated as II to IV according to the Shea's depth classification. Treatment was performed while all patients were on air mats. We selected drugs and treatment methods based on the previously established experimental design of Taguchi. Based on this, we created and adapted 16 different component combination treatment programs in accordance with the L16 rectangular cross table. The following component factors were adopted: A: types of covering substances on the wound surface (Elase ointment, isodine sugar, isodine gel solcoseryl ointment); B: Isalopan powder; C: Spray of 10 ml physiological saline containing 500 microg of prostaglandin (concentration 0.005%); D: daily number of treatments; and F: presence or absence of tapping. We serially measured the wound surface area as an index of the speed of wound healing, and measured the interval (day) until the area decreased to one half of the original size (T1/2, half life). We analyzed data on one combination treatment each in 16 patients. Analysis of variance of the above factors showed significant F values for factors A, B, D and F. The contribution rates for factors A, B, D and F were 37.84%, 8.47%, 14.98% and 13.81%, respectively. The error term (e) was 16.37%. Optimal results were seen in the groups in which solcoseryl ointment had been applied twice a day. In this study, prostaglandin, which had been anticipated to be effective, did not show any effects. The error term (e) suggests the presence of other healing factors including individual differences. Concerning this point, it well be necessary to examine a larger number of patients in the future. With ointment treatment alone, without using an air mat, it was confirmed that bedsore area reduction was extremely unstable. Decompression of the affected part may be a basic prevention factor and essential treatment of bedsores.

Molecular biology of pharmacologic vitreolysis

PURPOSE

Pharmacologic vitreolysis is a promising new therapy to improve vitreoretinal surgery and, ultimately, prevent disease by mitigating the contribution of vitreous to retinopathy. The mechanism of action of the agents being developed for pharmacologic vitreolysis remains unclear. The experiments in this thesis test the hypothesis that pharmacologic vitreolysis agents break down vitreous macromolecules into smaller particles.

METHODS

Microplasmin, hyaluronidase, and collagenase were tested in solutions of hyaluronan (n = 15) and collagen (n = 15), explants of bovine vitreous (n = 15), dissected porcine vitreous (n = 9), and intact porcine eyes (n = 18). There were also 21 controls, totaling 93 specimens. Vitreous macromolecule sizes were determined with dynamic light scattering (DLS), performed at intervals from 10 minutes to 24 hours following injections.

RESULTS

Studies of DLS reproducibility showed a coefficient of variance of less than 3.3% in all but one specimen. Microplasmin decreased porcine vitreous macromolecule size in a dose-dependent manner (correlation coefficient r = 0.93), with an 85% reduction after a 30-minute exposure to the maximum dose. Hyaluronidase decreased vitreous macromolecule size in hyaluronan solutions by 50% at high (1,000 IU/mL, P < .001) doses and in bovine vitreous by 20%. Collagenase decreased macromolecule size in collagen solutions by 20% at both low (1 mg/mL, P < .001) and high (10 mg/mL, P < .001) doses, but not at all in bovine vitreous.

CONCLUSIONS

Pharmacologic vitreolysis can induce a significant decrease in vitreous macromolecule sizes, depending upon the pharmacologic agents and the experimental model. Broad-spectrum agents were more effective than substrate-specific enzymes. Defining the molecular biology of pharmacologic vitreolysis has implications for surgical developments and may impact upon the design of clinical trials to induce prophylactic posterior vitreous detachment.

Safety and efficacy of dispase and plasmin in pharmacologic vitreolysis

PURPOSE

To evaluate the safety and efficacy of dispase and plasmin when inducing posterior vitreous detachment (PVD) by intravitreous injection in rabbit eyes.

METHODS

Forty-eight young pigmented rabbits were randomized into six groups. Groups 1 and 5 received 0.025 U dispase in test eyes; group 2, 0.1 U dispase; groups 3 and 6, 1 U plasmin; and group 4, 4 U plasmin. All groups received PBS in control eyes. Groups 5 and 6 were euthanatized 15 minutes after surgery for ocular histologic examination. The remaining groups (groups 1-4) received indirect ophthalmoscope and biomicroscopy 15 and 30 minutes; 1, 2, and 8 hours; and 1, 3, and 7 days after surgery. Ultrasonography and electroretinogram were performed 1 hour and 1 and 7 days after surgery. The eyes then were examined by scanning and transmission electron microscopy.

RESULTS

Partial or complete PVDs were observed in the eyes that received dispase and plasmin, confirmed by the results of scanning electron microscopy. Light microscopy showed inflammation in both dispase- and plasmin-treated eyes of groups 5 and 6. However, whereas in plasmin-treated eyes the ERG and cell ultrastructure showed no significant changes, in dispase-treated eyes, the amplitudes of ERG showed a significant reduction from baseline and ultrastructural damage to the retina was detected by transmission electron microscopy. Cell damage, preretinal hemorrhage, and cataract were also observed in these eyes. No changes were observed in the control eyes.

CONCLUSIONS

Intravitreal injection of dispase at 0.025 U or more can induce PVD, but it is not safe. Plasmin (1-4 U) is safer, except for the potential risk of inducing intraocular inflammation.

Effect of plasmin on movement characteristics of ejaculated bull spermatozoa

Proteolytic enzymes appear to have an essential role in multiple phases of mammalian fertilization. Several observations suggest that the plasminogen activator/plasmin system might also play a role in mammalian fertilization. Movement characteristics of bovine sperm incubated with different concentrations of plasmin were investigated using a computer-assisted automated semen analysis system. Sperm were incubated up to 4h in a modified Tyrode's medium (control) and 0.1, 1, 10 and 100 mU/ml of plasmin. The percentage motile sperm was significantly higher at 0 h for sperm incubated in 1, 10, and 100 mU of plasmin. Relative to sperm incubated in control medium, lateral head displacement (ALH), curvilinear velocity, beat cross frequency, path velocity and straight line velocity (VSL) of sperm treated with 100 mU of plasmin for 0 h were increased. After 2h of incubation, sperm treated with 100 mU of plasmin showed an increase in ALH, but a decrease in VSL, straightness and linearity. The effect of plasmin on most motility parameters appears to be direct since all these parameters were affected at 0 h of incubation. Our results support the notion of hyperactivation of bovine spermatozoa following incubation with different concentrations of plasmin. The present work provides additional information to further characterize motility movement of bovine sperm associated with final preparation for fertilization.

[An experimental study on dissolving and detaching vitreoretinal interface with enzymes]

OBJECTIVE

To investigate the safety dosage of intravitreal injection of Plasmin, Hyaluronidase and their combination and to evaluate their efficacy in the formation of posterior vitreous detachment (PVD) through animal experiments.

METHODS

Eight rabbits each were randomly assigned to one of six groups and one eye of each rabbit were experimental eye, the other is control eye. The position of drug injection was in posterior 1/3 of vitreous before papillary. The drug-injection groups were assigned as following: the first group-Hyaluronidase 20 IU (0.1 ml BSS), the second group-Hyaluronidase 30 IU (0.1 ml BSS), the third group-Plasmin 1 IU (0.1 ml BSS), the forth group-Plasmin 2 IU (0.1 ml BSS), the fifth group-Plasmin 3 IU (0.1 ml BSS), the sixth group- Hyaluronidase 20 IU (0.05 ml BSS) combined with Plasmin 1 IU (0.05 ml BSS); the control eyes were injected with BSS (0.1 ml) at the same position. The experimental rabbits were followed for 2 weeks, and in this period all eyes were examined with slit-lamp biomicroscopy, +90 D preset lens, indirect ophthalmoscope, electroretinography, B-scan, and optical coherence tomography. After two weeks, the animals were killed and the eyes enucleated. Scan electron and light microscopy were performed.

RESULTS

Hyaluronidase concentration of 20 IU, Plasmin concentration of 1 IU and their combination didn't produce inflammatory response and retinal toxicity in the experimental eyes. 30 IU Hyaluronidase and 2 IU Plasmin both caused mild inflammatory response in the vitreous without retinal histological changes, while the latter caused a reversible decrease in the ERG b-wave. 3 IU of Plasmin caused severe inflammatory response with retinal histological and electroretinographic changes. In safety dosage neither Hyaluronidase nor Plasmin alone were successful in producing completely posterior vitreous detachment (PVD), but the latter can produce partial PVD. The combination of Plasmin (1 IU) and Hyaluronidase (20 IU) was effective on producing completely PVD without retinal toxicity.

CONCLUSION

20 IU of Hyaluronidase and 1 IU of Plasmin are safe to retina and others structures in the eyes without any toxicity. Posterior vitreous injection of Hyaluronidase (20 IU) combined with Plasmin (1 IU) can produce complete posterior vitreous detachment.

Ultrastructure of internal limiting membrane removed during plasmin-assisted vitrectomy from eyes with diabetic macular edema

PURPOSE

To study the effect of autologous plasmin enzyme (APE) on the adhesion of the vitreous cortex to the internal limiting membrane (ILM) in eyes with diabetic macular edema.

DESIGN

Nonrandomized, comparative, interventional case series.

PARTICIPANTS

Ten eyes of 10 patients with diabetic macular edema without a posterior vitreous detachment (PVD), which were treated with APE as an adjunct to conventional pars plana vitrectomy, and 10 eyes of 9 patients without a PVD, which underwent pars plana vitrectomy without APE, were studied.

METHODS

In the APE group, 0.4 IU of APE was injected into the midvitreous cavity in 9 eyes, and 0.8 IU of APE in 1 eye. Thirty minutes after plasmin injection, the eyes underwent pars plana vitrectomy with ILM peeling. All eyes in the control group had conventional vitreous surgery with ILM peeling. The removed ILMs were investigated for the presence of vitreous and for ultrastructural differences by transmission and scanning electron microscopy.

MAIN OUTCOME MEASURES

The status of the vitreous and induction of a PVD during surgery, and the presence of vitreous and ultrastructural differences of the removed ILM by transmission and scanning electron microscopy.

RESULTS

In APE-treated eyes, the degree of liquefaction of the vitreous was graded as high in 4 eyes. Spontaneous PVD occurred in 2 eyes, whereas core vitrectomy with a maximum vacuum of 100 mmHg induced a PVD in 2 additional eyes. In the control group, 8 eyes required suction with a maximum of 200 mmHg to induce the PVD. Scanning electron micrography of the removed ILM in the APE-treated eyes showed a smooth surface on the vitreous side in 8 eyes and only sparse collagen fibers in 2 eyes. Conversely, in the control group, dense vitreous fibers were found in 4 eyes, sparse collagen fibrils in 3 eyes, and a smooth retinal surface in 3 eyes.

CONCLUSIONS

These findings indicate that APE helps separate the vitreous hyaloid from the ILM surface and may be a useful adjunct to conventional vitreous surgery for diabetic macular edema.