Systemic treatments for noninfectious vitreous inflammation.

Vitreous inflammation, or vitritis, may result from many causes, including both infectious and noninfectious, including rheumatologic and autoimmune processes. Vitritis is commonly vision threatening and has serious sequelae. Treatment is frequently challenging, but, today, there are multiple methods of systemic treatment for vitritis. These categories include corticosteroids, antimetabolites, alkylating agents, T-cell inhibitors/calcineurin inhibitors, and biologic agents. These treatment categories were reviewed last year, but, even over the course of just a year, many therapies have made progress, as we have learned more about their indications and efficacy. We discuss here discoveries made over the past year on both existing and new drugs, as well as reviewing mechanisms of action, clinical dosages, specific conditions that are treated, adverse effects, and usual course of treatment for each class of therapy.

Drug delivery implants in the treatment of vitreous inflammation.

The eye is a model organ for the local delivery of therapeutics. This proves beneficial when treating vitreous inflammation and other ophthalmic pathologies. The chronicity of certain diseases, however, limits the effectiveness of locally administered drugs. To maintain such treatments often requires frequent office visits and can result in increased risk of infection and toxicity to the patient. This paper focuses on the implantable devices and particulate drug delivery systems that are currently being implemented and investigated to overcome these challenges. Implants currently on the market or undergoing clinical trials include those made of nonbiodegradable polymers, containing ganciclovir, fluocinolone acetonide, triamcinolone acetonide, and ranibizumab, and biodegradable polymers, containing dexamethasone, triamcinolone acetonide, and ranibizumab. Investigational intravitreal implants and particulate drug delivery systems, such as nanoparticles, microparticles, and liposomes, are also explored in this review article.

Serum levels of intravitreal bevacizumab after vitrectomy, lensectomy and non-surgical controls.

PURPOSE: To determine serum level differences of intravitreally-placed bevacizumab after vitrectomy and lensectomy-vitrectomy and to compare these with non-operated eyes in a rabbit model. METHODS: Five Dutch-belted rabbits underwent pars plana vitrectomy (PPV), five rabbits underwent pars plana lensectomy (PPL) and five rabbits served as non-surgical controls. Twelve days following the surgical procedures, each operated eye underwent an intravitreal injection consisting of 1.25 mg/0.05 mL bevacizumab. Serum levels from each rabbit were drawn on days 2, 4, 7, 10, 14, 21, 28 and 35 and were measured with ELISA immunoassay. RESULTS: The average peak serum concentration (Cmax) was highest for the PPL group (11.33 µg ± 3.48 mL), and was similar between the PPV (5.35 µg ± 2.69 mL) and non-surgical control groups (5.35 µg ± 0.69 mL). The average time to maximal plasma concentration (Tmax) in days was earliest for the PPL group (2.8 ± 0.47), followed by the PPV (5.6 ± 0.84) and non-surgical control groups (6.4 ± 0.71). The PPL group had higher serum levels than the other two groups until day 7 that was significant only at day 2 (p < 0.0001). After day 4, there were no significant differences or trends between any of the three groups. The half-life (T1/2) was fastest for the PPL group (1.41 ± 0.21 d) followed by the PPV (2.80 ± 3.35 d) and non-surgical control groups (6.69 ± 10.4 d). CONCLUSIONS: Serum bevacizumab levels were initially elevated following lensectomy and vitrectomy compared to non-surgical eyes following intravitreal injection. The half-life of bevacizumab was prolonged in non-surgical eyes presumably due to a slower release from the vitreous cavity.

The effect of intravitreal bevacizumab and ranibizumab on cutaneous tensile strength during wound healing.

PURPOSE: To investigate the effect of intravitreal bevacizumab and ranibizumab on wound tension and by histopathology during cutaneous wound healing in a rabbit model and to compare this effect to placebo intravitreal saline controls 1 and 2 weeks following intravitreal injection. METHODS: A total of 120 New Zealand white rabbits were randomly assigned to one of three treatment groups each consisting of 40 rabbits. Each group received intravitreal injections of bevacizumab, ranibizumab, or normal saline. Immediately afterwards, each rabbit underwent four 6 mm full-thickness dermatologic punch biopsies. Twenty rabbits from each agent group underwent wound harvesting on day 7 or day 14. The skin samples were stained for CD34 for vascular endothelial cells on day 7, and maximal wound tensile load was measured on days 7 and 14. Quantitative assessment of mean neovascularization (MNV) scores was obtained from 10 contiguous biopsy margin 400× fields of CD34-stained sections by two independent observers. RESULTS: Wound tension reading means (N) with standard error and adjusted P-values on day 7 were: saline placebos, 7.46 ± 0.87; bevacizumab, 4.50 ± 0.88 (P = 0.041); and ranibizumab, 4.67 ± 0.84 (P = 0.025). On day 14 these were: saline placebos, 7.34 ± 0.55; bevacizumab, 6.05 ± 0.54 (P = 0.18); and ranibizumab 7.99 ± 0.54 (P = 0.40). MNV scores in CD34 stained sections were: saline controls, 18.31 ± 0.43; bevacizumab, 11.02 ± 0.45 (P < 0.0001); and ranibizumab, 13.55 ± 0.43 (P < 0.0001). The interobserver correlation coefficient was 0.928. CONCLUSION: At day 7, both anti-vascular endothelial growth factor (anti-VEGF) agents had significantly suppressed MNV scores and exerted a significant reduction of cutaneous wound tensile strength compared with saline controls. At day 14, neither agent produced a significant effect on tensile wound strength. Since angiogenesis is an integral component of the proliferative phase of wound healing, we encourage clinicians to be aware of their patients' recent surgical history during intravitreal anti-VEGF therapy and to consider refraining from their use during the perioperative period.

Anatomic and pharmacokinetic properties of intravitreal bevacizumab and ranibizumab after vitrectomy and lensectomy.

PURPOSE: To determine the anatomic characteristics and pharmacokinetic properties of intravitreally placed bevacizumab and ranibizumab after pars plana lensectomy or pars plana vitrectomy and to compare these with nonoperated control eyes in a rabbit model. METHODS: Three groups of six Dutch-belted rabbits each underwent pars plana vitrectomy, pars plana lensectomy, or served as nonsurgical controls. Twelve days after surgery, 3 rabbits from each group underwent intravitreal injection in one eye with 1.25 mg/0.05 mL I-124-bevacizumab or 0.5 mg/0.05 mL I-124-ranibizumab. Serial imaging with integrated positron emission and computed tomography (PET/CT) were obtained on Days 0, 2, 5, 7, 14, 21, 28, and 35. Measured radioactivity emission in becquerels/milliliter was used to calculate the half-lives for each agent. RESULTS: The intravitreally placed radiolabeled agents were contained within the vitreous cavity for the duration of the study. The average clearance half-lives with standard error for bevacizumab and ranibizumab after correction for radioactive decay were, respectively, 4.22 ± 0.07 days and 2.81 ± 0.05 days in unoperated eyes, 2.30 ± 0.09 days (P < 0.0001) and 2.13 ± 0.05 days (P < 0.0001) after vitrectomy, and 2.08 ± 0.07 days (P = 0.0001) and 1.79 ± 0.05 days (P < 0.0001) after lensectomy. CONCLUSION: Intravitreal retention was longer for bevacizumab than ranibizumab within all study groups and was significantly reduced after vitrectomy and lensectomy for both agents. Consideration for more frequent intravitreal anti-vascular endothelial growth factor dosing regimens may be made for patients whose treated eyes have undergone previous vitrectomy or who are aphakic.

Robot-assisted versus laparoscopic gastric bypass: comparison of short-term outcomes.

BACKGROUND: Roux-en-Y gastric bypass is an effective treatment for severe obesity and obesity-related comorbidities. Presently, gastric bypass is performed most often laparoscopically, although a robotic-assisted procedure is the preferred approach for an increasing number of bariatric surgeons. METHODS: This retrospective study compared the results of 100 Roux-en-Y gastric bypass operations using the da Vinci robot and 100 laparoscopic Roux-en-Y gastric bypasses performed laparoscopically. Short-term outcomes were determined by evaluating mortality, length of stay, length of operation, return to the operating room within 90 days of operation, conversions to open procedure, leaks, strictures, transfusions, and hospital readmissions. RESULTS: There was no mortality, pulmonary embolus, or conversion to open procedure in either group. Both the laparoscopic and robotic operative times decreased progressively, although the robotic operation time was longer (mean, 144 versus 87 min, P < 0.001). The length of stay was shorter for the robotic-assisted group (37 versus 52 h, P < 0.001), and 60% of these patients were discharged after one night's stay (P < 0.001). There were fewer transfusions (P = 0.005) and readmissions (P = .560) in the robotic group. The stricture rate was higher in the first 50 robotic procedures (17 mm gastrotomy) but resolved in the second 50 procedures (21 mm gastrotomy). There was no difference in the rate of leak and return to the operating room between groups (both P > 0.05). CONCLUSIONS: These results indicate that Roux-en-Y gastric bypass can be performed safely with robotic assistance, even during the first 100 cases.

Systemic treatment of vitreous inflammation.

Non infectious vitreous inflammation is often vision threatening and can be associated with potentially life-threatening systemic conditions. Treatment is often challenging as it involves systemic medications that can be associated with adverse effects. The classes of drugs are ever expanding and include corticosteroids, antimetabolites, alkylating agents, T-cell and calcineurin agents, biologic agents, and interferons. Each class of systemic therapy for non-infectious vitreous inflammation is reviewed. We discuss the mechanisms of action, usual clinical dosages, the specific conditions that are treated, the adverse effects, and usual course of treatment for each class of therapy.

Intravitreal devices for the treatment of vitreous inflammation.

The eye is a well-suited organ for local delivery of therapeutics to treat vitreous inflammation as well as other pathologic conditions that induce visual loss. Several conditions are particularly challenging to treat and often require chronic courses of therapy. The use of implantable intravitreal devices for drug delivery is an emerging field in the treatment of vitreous inflammation as well as other ophthalmologic diseases. There are unique challenges in the design of these devices which include implants, polymers, and micro- and nanoparticles. This paper reviews current and investigational drug delivery systems for treating vitreous inflammation as well as other pathologic conditions that induce visual loss. The use of nonbiodegradable devices such as polyvinyl alcohol-ethylene vinyl acetate polymers and polysulfone capillary fibers, and biodegradable devices such as polylactic acid, polyglycolic acid, and polylactic-co-glycolic acid, polycaprolactones, and polyanhydrides are reviewed. Clinically used implantable devices for therapeutic agents including ganciclovir, fluocinolone acetonide, triamcinolone acetonide, and dexamethasone are described. Finally, recently developed investigational particulate drug delivery systems in the form of liposomes, microspheres, and nanoparticles are examined.

The catalytic function of the Rev1 dCMP transferase is required in a lesion-specific manner for translesion synthesis and base damage-induced mutagenesis.

The Rev1-Polzeta pathway is believed to be the major mechanism of translesion DNA synthesis and base damage-induced mutagenesis in eukaryotes. While it is widely believed that Rev1 plays a non-catalytic function in translesion synthesis, the role of its dCMP transferase activity remains uncertain. To determine the relevance of its catalytic function in translesion synthesis, we separated the Rev1 dCMP transferase activity from its non-catalytic function in yeast. This was achieved by mutating two conserved amino acid residues in the catalytic domain of Rev1, i.e. D467A/E468A, where its catalytic function was abolished but its non-catalytic function remained intact. In this mutant strain, whereas translesion synthesis and mutagenesis of UV radiation were fully functional, those of a site-specific 1,N(6)-ethenoadenine were severely deficient. Specifically, the predominant A-->G mutations resulting from C insertion opposite the lesion were abolished. Therefore, translesion synthesis and mutagenesis of 1,N(6)-ethenoadenine require the catalytic function of the Rev1 dCMP transferase, in contrast to those of UV lesions, which only require the non-catalytic function of Rev1. These results show that the catalytic function of the Rev1 dCMP transferase is required in a lesion-specific manner for translesion synthesis and base damage-induced mutagenesis.

Poleta, Polzeta and Rev1 together are required for G to T transversion mutations induced by the (+)- and (-)-trans-anti-BPDE-N2-dG DNA adducts in yeast cells.

Benzo[a]pyrene is an important environmental mutagen and carcinogen. Its metabolism in cells yields the mutagenic, key ultimate carcinogen 7R,8S,9S,10R-anti-benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide, (+)-anti-BPDE, which reacts via its 10-position with N2-dG in DNA to form the adduct (+)-trans-anti-BPDE-N2-dG. To gain molecular insights into BPDE-induced mutagenesis, we examined in vivo translesion synthesis and mutagenesis in yeast cells of a site-specific 10S (+)-trans-anti-BPDE-N(2)-dG adduct and the stereoisomeric 10R (-)-trans-anti-BPDE-N2-dG adduct. In wild-type cells, bypass products consisted of 76% C, 14% A and 7% G insertions opposite (+)-trans-anti-BPDE-N2-dG; and 89% C, 4% A and 4% G insertions opposite (-)-trans-anti-BPDE-N2-dG. Translesion synthesis was reduced by approximately 26-37% in rad30 mutant cells lacking Poleta, but more deficient in rev1 and almost totally deficient in rev3 (lacking Polzeta) mutants. C insertion opposite the lesion was reduced by approximately 24-33% in rad30 mutant cells, further reduced in rev1 mutant, and mostly disappeared in the rev3 mutant strain. The insertion of A was largely abolished in cells lacking either Poleta, Polzeta or Rev1. The insertion of G was not detected in either rev1 or rev3 mutant cells. The rad30 rev3 double mutant exhibited a similar phenotype as the single rev3 mutant with respect to translesion synthesis and mutagenesis. These results show that while the Polzeta pathway is generally required for translesion synthesis and mutagenesis of the (+)- and (-)-trans-anti-BPDE-N2-dG DNA adducts, Poleta, Polzeta and Rev1 together are required for G-->T transversion mutations, a major type of mutagenesis induced by these lesions. Based on biochemical and genetic results, we present mechanistic models of translesion synthesis of these two DNA adducts, involving both the one-polymerase one-step and two-polymerase two-step models.