Myung Hun Kim

Long-Term Efficacy and Rotational Stability of AcrySof Toric Intraocular Lens Implantation in Cataract Surgery

Purpose To evaluate the long-term efficacy and rotational stability of the AcrySof toric intraocular lens (IOL) in correcting preoperative astigmatism in cataract patients. Methods This prospective observational study included 30 eyes from 24 consecutive patients who underwent implantation of an AcrySof toric IOL with micro-coaxial cataract surgery between May 2008 and September 2008. Outcomes of visual acuity, refractive and keratometric astigmatism, and IOL rotation after 1 day, 1 month, 3 months, and long-term (mean, 13.3±5.0 months) follow-up were evaluated. Results At final follow-up, 73.3% of eyes showed an uncorrected visual acuity of 20/25 or better. The postoperative keratometric value was not different from the preoperative value; mean refractive astigmatism was reduced to -0.28±0.38 diopter (D) from -1.28±0.48 D. The mean rotation of the toric IOL was 3.45±3.39 degrees at final follow-up. One eye (3.3%) exhibited IOL rotation of 10.3 degrees, the remaining eyes (96.7%) had IOL rotation of less than 10 degrees. Conclusions Early postoperative and long-term follow-up showed that implantation of the AcrySof toric IOL is an effective, safe, and predictable method for managing corneal astigmatism in cataract patients.

Incidence of severe ventricular arrhythmias during pulmonary artery catheterization in liver allograft recipients

Liver allograft recipients may develop a hyperdynamic circulation and cardiac electrophysiologic abnormalities. The incidence of severe ventricular arrhythmias in liver allograft recipients during pulmonary artery (PA) catheterization was determined. One hundred five liver allograft recipients were studied prospectively; 5 of the patients with preexisting valvular heart disease, ischemic heart disease, or arrhythmias were excluded. Severe ventricular arrhythmia, defined as 3 or more consecutive ventricular premature beats occurring at a rate of >100 per minute, was observed in 37.0% of the patients during insertion of the catheter and in 25.0% of the patients during removal of the catheter. Two patients developed ventricular tachycardia, and 2 developed ventricular fibrillation; the arrhythmias in these 4 patients did not respond to appropriate pharmacological treatment but resolved promptly after removal of the PA catheter. The catheter transit time from the right ventricle to the pulmonary capillary wedge position was longer in patients with severe ventricular arrhythmia than in those without this arrhythmia (91.6 ± 103.6 s versus 53.3 ± 18.4 s, P < 0.05). In conclusion, patients undergoing liver transplantation have a high risk of developing a ventricular arrhythmia during PA catheterization. Liver Transpl 13:1451–1454. 2007.

Drug-inorganic-polymer nanohybrid for transdermal delivery.

For transdermal drug delivery, we prepared a drug-inorganic nanohybrid (FB-LDH) by intercalating a transdermal model drug, flurbiprofen (FB), into the layered double hydroxides (LDHs) via coprecipitation reaction. The X-ray diffraction patterns and FT-IR spectra of the FB-LDH indicated that the FB molecules were successfully intercalated via electrostatic interaction within the LDH lattices. The in vitro drug release revealed that the Eudragit(®) S-100 in release media could facilitate the drug out-diffusion by effectively replacing the intercalated drug and also enlarging the lattice spacing of the FB-LDH. In this work, a hydrophobic gel suspension of the FB-LDH was suggested as a transdermal controlled delivery formulation, where the suspensions were mixed with varying amounts of Eudragit(®) S-100 aqueous solution. The Frantz diffusion cell experiments using mouse full-skins showed that a lag time and steady-state flux of the drug could be controlled from 12.8h and 3.28μgcm(-2)h(-1) to less than 1h and 14.57μgcm(-2)h(-1), respectively, by increasing the mass fraction of Eudragit(®) S-100 solution in gel suspensions from 0% to 20% (w/w), respectively. Therefore, we conclude gel formulation of the FB-LDH have a potential for transdermal controlled drug delivery.

Surgical suture assembled with polymeric drug-delivery sheet for sustained, local pain relief

Surgical suture is a strand of biocompatible material designed for wound closure, and therefore can be a medical device potentially suitable for local drug delivery to treat pain at the surgical site. However, the preparation methods previously introduced for drug-delivery sutures adversely influenced the mechanical strength of the suture itself - strength that is essential for successful wound closure. Thus, it is not easy to control drug delivery with sutures, and the drug-delivery surgical sutures available for clinical use are now limited to anti-infection roles. Here, we demonstrate a surgical suture enabled to provide controlled delivery of a pain-relief drug and, more importantly, we demonstrate how it can be fabricated to maintain the mechanical strength of the suture itself. For this purpose, we separately prepare a drug-delivery sheet composed of a biocompatible polymer and a pain-relief drug, which is then physically assembled with a type of surgical suture that is already in clinical use. In this way, the drug release profiles can be tailored for the period of therapeutic need by modifying only the drug-loaded polymer sheet without adversely influencing the mechanical strength of the suture. The drug-delivery sutures in this work can effectively relieve the pain at the surgical site in a sustained manner during the period of wound healing, while showing biocompatibility and mechanical properties comparable to those of the original surgical suture in clinical use.

Heritability of Myopia and Ocular Biometrics in Koreans: The Healthy Twin Study

PURPOSE To estimate the heritabilities of myopia and ocular biometrics among different family types among a Korean population. METHODS We studied 1508 adults in the Healthy Twin Study. Spherical equivalent, axial length, anterior chamber depth, and corneal astigmatism were measured by refraction, corneal topography, and A-scan ultrasonography. To see the degree of resemblance among different types of family relationships, intraclass correlation coefficients (ICC) were calculated. Variance-component methods were applied to estimate the genetic contributions to eye phenotypes as heritability based on the maximum likelihood estimation. Narrow sense heritability was calculated as the proportion of the total phenotypic variance explained by additive genetic effects, and linear and nonlinear effects of age, sex, and interactions between age and sex were adjusted. RESULTS A total of 240 monozygotic twin pairs, 45 dizygotic twin pairs, and 938 singleton adult family members who were first-degree relatives of twins in 345 families were included in the study. ICCs for spherical equivalent from monozygotic twins, pooled first-degree pairs, and spouse pairs were 0.83, 0.34, and 0.20, respectively. The ICCs of other ocular biometrics were also significantly higher in monozygotic twins compared with other relative pairs, with greater consistency and conformity. The estimated narrow sense heritability (95% confidence interval) was 0.78 (0.71-0.84) for spherical equivalent; 0.86 (0.82-0.90) for axial length; 0.83 (0.76-0.91) for anterior chamber depth; and 0.70 (0.63-0.77) for corneal astigmatism. CONCLUSIONS The estimated heritability of spherical equivalent and ocular biometrics in the Korean population suggests the compelling evidence that all traits are highly heritable.

Can Peripheral Venous Pressure Be an Alternative to Central Venous Pressure During Right Hepatectomy in Living Donors

The safety of living donors is a matter of cardinal importance in addition to obtaining optimal liver grafts to be transplanted. Central venous pressure (CVP) is known to have significant correlation with the amount of bleeding during parenchymal transection and many centers have adopted CVP monitoring for right hepatectomy. However, central line cannulation can induce some serious complications. Peripheral venous pressure (PVP) has been suggested as a comparable alternative to CVP. The aim of this study was to determine whether a clinically acceptable agreement or a reliable correlation between CVP and PVP exist and if CVP can be replaced by PVP in living liver donors. A central venous catheter was placed through the right internal jugular vein and a peripheral venous catheter was inserted at antecubital fossa in the right arm. CVP and PVP were recorded in 15‐minunte intervals in 50 adult living donors. The paired data were divided into 3 stages: preparenchymal transection, parenchymal transection, and postparenchymal transection. A total of 1,430 simultaneous measurements of CVP and PVP were recorded. Overall, the PVP, CVP, and bias were 7.0 ± 2.46, 5.9 ± 2.32, and 1.16 ± 1.12 mmHg, respectively. A total of 88.9% of all measurements were clinically within acceptable limits of bias (±2 mmHg). Regression analysis showed a high correlation coefficient between PVP and CVP (r = 0.893; P < 0.001) and the limits of agreement were −1.03 to 3.34 overall. In conclusion, frequencies of differences, bias, correlation coefficient, and limits of agreement between PVP and CVP remained relatively constant throughout the operation. Therefore, PVP measurement in the arm can be an alternative to predict CVP and further, obviate central venous catheter‐related complications in living liver donors. Liver Transpl 13:1414–1421, 2007.

A retrospective contralateral study comparing deep anterior lamellar keratoplasty with penetrating keratoplasty.

Purpose: This study was conducted to compare endothelial cell (EC) loss, visual outcomes, and complications after deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK) in the contralateral eyes of the same patients. Methods: A retrospective cohort study was undertaken at the Samsung Medical Center, Seoul Korea. We reviewed the records of 8 patients (16 eyes) who underwent PK in one eye and DALK in the contralateral eye. The DALK procedures were performed according to the Anwar and Teichmann big-bubble technique. EC loss, visual acuity, refractive status, and complications were evaluated to compare these techniques. Results: EC density was significantly higher after DALK compared with PK (at 12 months: 2045.8 ± 664.8 vs. 1732.6 ± 793.2, P = 0.044; at 24 months: 1900.3 ± 352.2 vs. 1416.2 ± 456.1, P = 0.013). The mean postoperative refractive astigmatism was −3.46 ± 2.57 diopters in the DALK-operated eyes versus −3.38 ± 2.48 diopters in the PK-operated eyes (P = 0.780), and the mean postoperative best-corrected visual acuity was 0.14 and 0.13 logarithm of the minimum angle of resolution, respectively (P = 0.870). There were no significant differences in the uncorrected visual acuity, best-corrected visual acuity, and refractive error between the DALK-operated and PK-operated eyes throughout the follow-up period. Rejection episodes were reported in 2 PK-operated eyes. No graft failures occurred. Conclusions: Over the 2-year follow-up after DALK, EC loss was significantly lower, whereas the visual outcomes were comparable with those of the PK-operated eyes. No endothelial rejection occurred in the DALK-operated eyes. DALK is an effective alternative surgical procedure for corneal stromal pathologies.

Bioabsorbable bone plates enabled with local, sustained delivery of alendronate for bone regeneration.

We prepared a bone plate enabled with the local, sustained release of alendronate, which is a drug known to inhibit osteoclast-mediated bone resorption and also expedite the bone-remodeling activity of osteoblasts. For this, we coated a bone plate already in clinical use (PLT-1031, Inion, Finland) with a blend of alendronate and a biocompatible polymer, azidobenzoic acid-modified chitosan (i.e., Az-CH) photo-crosslinked by UV irradiation. As we performed the in vitro drug release study, the drug was released from the coating at an average rate of 4.03μg/day for 63days in a sustained manner. To examine the effect on bone regeneration, the plate was fixed on an 8mm cranial critical size defect in living rats and the newly formed bone volume was quantitatively evaluated by micro-computed tomography (micro-CT) at scheduled times over 8weeks. At week 8, the group implanted with the plate enabled with sustained delivery of alendronate showed a significantly higher volume of newly formed bone (52.78±6.84%) than the groups implanted with the plates without drug (23.6±3.81%) (p<0.05). The plate enabled with alendronate delivery also exhibited good biocompatibility on H&E staining, which was comparable to the Inion plate already in clinical use. Therefore, we suggest that a bone plate enabled with local, sustained delivery of alendronate can be a promising system with the combined functionality of bone fixation and its expedited repair.

Acute suppression of TGF-ß with local, sustained release of tranilast against the formation of fibrous capsules around silicone implants

We propose the acute, local suppression of transforming growth factor beta (TGF-ß), a major profibrotic cytokine, to reduce fibrosis around silicone implants. To this end, we prepared silicone implants that were able to release tranilast, a TGF-ß inhibitor, in a sustained manner for 5 days or 15 days. We performed histologic and immunohistochemical analyses for 12 weeks after the implantation of the implants in living rats. The capsule thicknesses and collagen densities significantly decreased compared with those around the non-treated silicone implants. Notably, early suppression of TGF-ß affected the fibrogenesis that actually occurs at the late stage of wound healing. This change may be ascribed to the decrease in monocyte recruitment mediated by early TGF-ß during the acute inflammatory reaction. Thus, a significant decrease in differentiated macrophages was observed along with a decrease in the quantity of TGF-ß and fibroblasts during the subsequent inflammation stage; these changes led to a diminished fibrotic capsule formation.

Mucoadhesive microparticles with a nanostructured surface for enhanced bioavailability of glaucoma drug.

Topical drug administration to the eye is limited by low drug bioavailability due to its rapid clearance from the preocular surface. Thus, multiple daily administrations are often needed, but patient compliance is low, hence a high chance of unsatisfactory treatment of ocular diseases. To resolve this, we propose mucoadhesive microparticles with a nanostructured surface as potential carriers for delivery of brimonidine, an ocular drug for glaucoma treatment. For sustained drug delivery, the microparticles were composed mainly of a diffusion-wall material, poly(lactic-co-glycolic acid) and a mucoadhesive polymer, polyethylene glycol, was used as an additive. Due to their nanostructured surface, the microparticles with a mucoadhesive material exhibited a 13-fold increase in specific surface area and could thus adhere better to the mucous layer on the eye, as compared with the conventional spherical microparticles. When loaded with brimonidine, the mucoadhesive microparticles with a nanostructured surface increased both drug bioavailability and its activity period by a factor of more than 2 over Alphagan P, a marketed eye drop of brimonidine.