A novel bleb revision technique: lining with tenon's patch graft for treatment of large, ischemic, leaking blebs with severe conjunctival scarring after trabeculectomy.

PURPOSE: We report a new bleb lining technique with Tenon's patch graft for late-onset leakage from large ischemic bleb with severe conjunctival scarring and impractical conjunctival mobilization after trabeculectomy. STUDY DESIGN: Retrospective case series. METHODS: This study includes six cases with late-onset leakage from large ischemic blebs. Small Tenon's tissue is dissected from the incisional site or a previously made inferior incision for Tenon's anesthesia. A passage is created from the small incision to the leaking area of the bleb using a bleb knife or micro scissors. The Tenon's tissue, stained with indocyanine green, is inserted under the ischemic bleb's conjunctiva. A transconjunctival compression suture is placed across the leaking point to fix the Tenon patch graft positionally. RESULTS: In all cases, bleb leakage was completely sealed immediately after surgery. In 4 cases, the closure of the bleb leakage was maintained after surgery during the follow-up period (6-17 months). In two cases, bleb leakage recurred from different leaking points 7 or 9.5 months after the surgery; however, repeated tenon's patch lining revisions successfully closed these leakages. The intraocular pressure at the final visit was 5-13 mmHg (median, 10 mmHg) without glaucoma medication or additional glaucoma surgery. CONCLUSION: Tenon's patch-lining technique is a promising method for bleb leakage with large ischemic bleb and impractical conjunctival mobilization.

Relationship between Inter-Eye Asymmetries in Corneal Hysteresis and Visual Field Severity in Patients with Primary Open-Angle Glaucoma.

This study investigated the influence of asymmetric corneal hysteresis (CH) on asymmetric visual field impairment between right and left eyes in patients with primary open-angle glaucoma (POAG) without a history of intraocular surgery. CH, corneal resistance factor (CRF), and corneal compensated intraocular pressure (IOPcc) were measured using the Ocular Response Analyzer. Differences between the eyes (right eye-left eye: DIFRL) and CH-based and in target parameters (higher CH eye-lower CH eye: DIFCH) were calculated in the same patient. In 242 phakic eyes of 121 patients, older age (p < 0.001), lower CH (p = 0.001), and lower CRF (p = 0.007) were significantly associated with worse standard automated perimetry (SAP) 24-2 mean deviation (MD). The DIFsRL in axial length (p = 0.003), IOPcc (p = 0.028), and CH (p = 0.001) were significantly associated with the DIFRL in SAP24-2 MD, but not in central corneal thickness (CCT), Goldmann applanation tonometry (GAT) measurement, and CRF. When dividing the patients into two groups based on the median of the CH DIFsCH (0.46), the DIFsCH in CRF (p < 0.001), IOPcc (p < 0.001), CCT (p = 0.004), SAP24-2 MD (p < 0.001), and SAP10-2 MD (p = 0.010) were significantly different between the groups. Large inter-eye asymmetry in CH is an important explanatory factor for disease worsening in patients with POAG.

Formulation of Biopharmaceutical Dry Powder Inhaler Using the Void Forming Index (VFI) to Detect and Avoid Powder Caking in Dry Powder Inhaler Formulations.

It is mandatory to detect the powder cohesiveness of biopharmaceutical dry powder inhaler (Bio-DPI) formulations and their effect on their performance. Normally, Bio-DPI formulations consist of highly cohesive components with higher drug amounts than small molecules. Herein, a formulation study of a high-drug-ratio Bio-DPI was performed, detecting the risk of powder caking in DPI formulations. The Bio-DPI formulation was manufactured via the spray-dry method followed by mixing with excipients. Powder caking was detected through the void forming index (VFI), which was calculated using pressure drop measured by inverse gas chromatography (iGC). Since VFI can be used to evaluate the structural changes induced by powder caking over time with less than 1 g of sample, VFI is considered suitalbe to apply for DPI formulation screening. The risk of powder caking was detected in spray dryed particles at more than 45% relative humidity (RH) humidity condition, mannitol (as a carrier particle) and magnesium stearate (as a lubricant) were added to the formulations. With formulation screening, addition of more than 40% of mannitol was suggested to reduce the risk of powder caking. Selected DPI formulation remained higher emitted ratio (95.6%), than spray dried particle (52.5%) at 25 °C 65% RH condition for 1-month storage. In conclusion, VFI measurement is useful for selecting the DPI formulation by mitigating powder caking risk with limited samples.

Comparisons of Aluminum and Silica Elution from Various Glass Vials.

To understand the risk of particle formation in glass vials, we investigated the correlation between vial surface condition and alminum (Al) or silicon (Si) elution using various suppliers' vials with or without surface treatment. The elution of Si, which can also be an indicator of Al elution, consists of two phases; the first phase is influenced by roughness of the glass surface at the time of filling, and the second phase is dependent on the fundamental elution rate from the glass tube. When vials were filled with citrate buffer at pH 7, vials with varied surface conditions showed the most obvious differences in Al and Si elution. Sulfur-treated vials showed slightly lower Al and Si elution than the non-treated vials. It is considered that this effect of the sulfur treatment on elution is due to the surface being smoothed during heat treatment after the washing process. Different from the sulfur treatment, silicon dioxide (SiO2)-coated vials hardly showed any Al elution as long as the surface was fully coated with the SiO2 layer. It was found that the protective effect of the SiO2 layer against Al elution is more effective in a vial filled with a solution having a lower pH, due to the lower Si dissolving rate occurring at a lower pH. As shown above, pre-measuring the Si and Al present in a citrate buffer at pH 7 placed within a glass container can be a useful tool for selecting the appropriate container for liquid drugs.

Aluminum elution and precipitation in glass vials: effect of pH and buffer species.

Inorganic extractables from glass vials may cause particle formation in the drug solution. In this study, the ability of eluting Al ion from borosilicate glass vials, and tendencies of precipitation containing Al were investigated using various pHs of phosphate, citrate, acetate and histidine buffer. Through heating, all of the buffers showed that Si and Al were eluted from glass vials in ratios almost the same as the composition of borosilicate glass, and the amounts of Al and Si from various buffer solutions at pH 7 were in the following order: citrate > phosphate > acetate > histidine. In addition, during storage after heating, the Al concentration at certain pHs of phosphate and acetate buffer solution decreased, suggesting the formation of particles containing Al. In citrate buffer, Al did not decrease in spite of the high elution amount. Considering that the solubility profile of aluminum oxide and the Al eluting profile of borosilicate glass were different, it is speculated that Al ion may be forced to leach into the buffer solution according to Si elution on the surface of glass vials. When Al ions were added to the buffer solutions, phosphate, acetate and histidine buffer showed a decrease of Al concentration during storage at a neutral range of pHs, indicating the formation of particles containing Al. In conclusion, it is suggested that phosphate buffer solution has higher possibility of forming particles containing Al than other buffer solutions.

Effects of phosphate buffer in parenteral drugs on particle formation from glass vials.

The characteristics of inorganic particles generated in glass vials filled with phosphate buffer solutions were investigated. During storage, particles were visually detected in the phosphate buffer solution in particular glass vials which pass compendial tests of containers for injectable drugs. These particles were considered to be different from ordinal glass delamination, which has been reported in a number of papers because the particles were mainly composed of Al, P and O, but not Si. The formation of the particles accelerated at higher storage temperatures. Among the surface treatments tested for the glass vials, sulfur treatment showed a protective effect on the particle formation in the vials, whereas the SiO(2) coating did not have any protective effects. It was found that the elution ratio of Al and Si in the solution stored in the glass vials after the heating was similar to the ratio of Al and Si in borosilicate glass. However, the Al concentration decreased during storage (5°C, 6 months), and consequently, particle formation was observed in the solution. Adding citrate, which is a chelating agent for Al, effectively suppressed the particle formation in the heated solution. When 50 ppb and higher concentrations of Al ion were added to the phosphate buffer solution, the formation of white particles containing Al, P and O was detected. It is suggested that a phosphate buffer solution in a borosilicate glass vial has the ability to form particles due to interactions with the Al that is eluted from the glass during storage.

Fc domain mediated self-association of an IgG1 monoclonal antibody under a low ionic strength condition.

Recently, we reported that IgG1 monoclonal antibody A (MAb A) underwent liquid-liquid phase separation and separated into light and heavy phases under a low ionic strength condition. The liquid-liquid phase separation was induced due to self-association of MAb A in the heavy phase when the initial concentration of MAb A was between the two critical concentrations [Nishi et al., Pharm. Res., 27, 1348-1360 (2010)]. Here, we determined the interaction site of MAb A by using proteolytic Fab and Fc fragments of MAb A. The mean hydrodynamic diameter of the Fc fragment increased in a low ionic strength buffer, and furthermore the SPR measurement detected interactions of the Fc fragment with both whole MAb A and the Fc fragment, whereas the Fab fragment interacted with neither whole MAb A nor the Fc fragment. No binding was detected under an isotonic ionic strength condition. Zeta potential of MAb A was significant positive below pH 5.5 and negative above pH 6.5. Between pH 5.5 and 6.5 where the phase separation is significantly induced, MAb A had only a small positive or negative net charge. The isothermal titration calorimetry dilution method revealed that dissociation of MAb A accompanied endothermic heat changes, suggesting that intermolecular interactions among MAb A molecules were attributed to the enthalpically driven process. These results suggest that liquid-liquid phase separation of MAb A is mediated by a weak electrostatic intermolecular interaction among MAb A molecules mainly at Fc portions.

Phase separation of an IgG1 antibody solution under a low ionic strength condition.

PURPOSE: Phase separation of monoclonal antibody A (MAb A) solution and its relation to protein self-association are studied. METHODS: A phase diagram of MAb A and its dependence on ionic strength and pH were investigated. The protein self-associations were characterized by dynamic light scattering (DLS), analytical ultracentrifugation analysis (AUC) and viscosity measurement. RESULTS: MAb A solution with a clear appearance in an isotonic ionic strength condition turned opalescent in a low ionic strength condition, followed by liquid-liquid phase separation (LLPS) into light and heavy phases. The protein concentrations of the two phases were dependent on the ionic strength and pH. The two phases became reversibly miscible when the ionic strength or temperature was increased. DLS and AUC showed that MAb A under a low ionic strength condition self-associates at a protein concentration above the critical concentration of 16.5 mg/mL. The viscosity of the heavy phase was high and dependent on the shear rate. These results indicate that attractive protein-protein interaction in the heavy phase induces LLPS. CONCLUSIONS: LLPS was induced in MAb A solution in a low ionic strength condition due to reversible protein self-association mediated mainly by attractive electrostatic interaction among the MAb A molecules in the heavy phase.

Relativistic quasidegenerate perturbation theory with four-component general multiconfiguration reference functions.

Relativistic quasidegenerate perturbation theory (QDPT) using general multiconfiguration (GMC) reference functions is developed and implemented. It is the relativistic counterpart of the nonrelativistic QDPT with GMC reference and thus retains all the advantages of the nonrelativistic GMC reference QDPT, such as applicability to any configuration space and small computational cost compared to the complete configuration-space case. The method is applied to the potential-energy curves of the ground states of I(2) and Sb(2) molecules, the excitation energies of CH(3)I, and the energies of the lowest terms of C, Si, and Ge atoms, and is shown to provide a balanced description of potential-energy curves and accurate transition energies for systems containing heavy elements and to provide much better results compared to the reference function (i.e., active space configuration interaction) level.