Evaluation of a human capsular bag model for secondary cataract determination after intraocular lens implantation

PURPOSE

To investigate the effect of different intraocular lenses (IOLs) on lens epithelial cells (LECs) and on human capsular bags in vitro and to evaluate the transferability of this model to clinical situations.

METHODS

Sham cataract surgery, including IOL-into-the-bag implantation, was performed on 38 donor eyes after removal of the cornea. The capsular bag including the IOL was removed, pinned on a culture dish, covered with medium, and incubated. Two different IOLs were compared per pair of donor eyes. In each pair of donor eyes, the two different IOLs to be compared were implanted individually into capsular bags. The time required for complete coverage of the posterior capsule by a confluent monolayer of LECs was documented. The following IOLs were compared: three-piece acrylic IOLs of different sizes and single-piece polymethylmethacrylate (PMMA) versus acrylic IOLs.

RESULTS

A complete monolayer of LECs on the posterior capsule was observed to form at times varying from 8 days (PMMA IOLs) to more than 60 days (three-piece hydrophobic acrylic IOLs). A significant difference between PMMA IOLs and hydrophobic acrylic IOLs was found.

CONCLUSIONS

The human capsular bag model employed allows short-term evaluation of secondary cataract formation for different IOLs. This model's correlation with clinical results is good.

[Non-contact donor cornea trephination with a flying spot excimer laser system]

BACKGROUND

One of the most common complications after mechanical penetrating keratoplasty is the occurrence of irregular astigmatism. We developed a method to prepare donor grafts for transplantation applying excimer laser techniques. The quality of the cut edges and exposure time were evaluated.

MATERIALS AND METHODS

The beam of an experimental excimer laser (OPTex, Lambda Physik) was homogenized and guided by an optical system including lenses and scanner mirrors. A special software was used to conduct the laser beam in a circular mode over the surface of the cornea. Corneas from porcine eyes were stabilized in an artificial anterior chamber. Twenty in vitro explants were trephinated applying our method and subsequently investigated by electron microscopy and histology.

RESULTS

All experiments provided regular and smooth cut edges. The average exposure time until perforation was 10.5 min (SD 2.7 min), the diameter of the grafts was 8.0 mm.

CONCLUSION

The experiments showed the possibility of non-contact trephination and generation of smooth cut edges with a rotating focussed excimer laser beam in a porcine cornea model. A major advantage of the system is the possibility of customized "tailored" grafts.

[Ocular toxocariasis. Diagnostic and therapeutic options]

BACKGROUND

The diagnosis of ocular toxocariasis can be difficult and the aim of this study was to evaluate the benefit of ELISA testing of vitreous body fluid.

PATIENTS AND METHODS

We present five consecutively treated patients with ocular symptoms of toxocariasis, three of these patients presenting with epiretinal membranes and subretinal granulomas were vitrectomized. Vitreous and body fluid and serum were tested for toxocara antibodies by ELISA. Moreover vitreous body fluid of 10 patients with epiretinal membranes of other origins were examined by the same ELISA.

RESULTS

In all three operated patients toxocara antibodies were detected in the vitreous fluid but ELISA testing of serum samples was negative in two of the three patients. Visual acuity increased or remained stable in the operated patients. The ELISA test was negative in all vitreous fluid samples of the control group.

CONCLUSIONS

ELISA testing of vitreous body fluid can prove the presence of toxocara infection when no systemic signs of infection are present and no antibodies are detectable in the serum. Well-timed vitrectomy is a suitable therapy for vitreo-retinal complications in ocular toxocariasis to improve prognosis and to confirm the diagnosis.

Effekt von Suramin auf Proliferation und Migration von Linsenepithelzellen in vitro

BACKGROUND

New approaches for the treatment of secondary cataract focus on a pharmacological therapy to prevent posterior capsule opacification. In this study we investigated the effect of the naphthylurea suramin in vitro in a cell culture model.

MATERIAL AND METHODS

Cell proliferation was measured using a proliferation assay and cell migration with a migration assay. Analyses of suramin toxicity were carried out using trypan blue staining.

RESULTS

A significant dose-dependent effect of suramin on the inhibition of LEC proliferation and migration was found even after short (1 or 2 h) incubation times ( p<0.01). Cell lysis reflecting a cytotoxic effect of suramin was not found even with high concentrations. However, preincubation of lens capsules with suramin did not prevent LECs from migrating compared to control cultures.

CONCLUSION

These results demonstrate the efficiency of suramin in vitro to inhibit migration of HLEC which can be explained by blocking growth factor-mediated effects on the cells. However, further investigations on the pharmacokinetic properties of suramin and possible side-effects on other intraocular tissues must follow.

Isolation and characterization of the prokaryotic proteasome homolog HslVU (ClpQY) from Thermotoga maritima and the crystal structure of HslV

Heat-shock locus VU (HslVU) is an ATP-dependent proteolytic system and a prokaryotic homolog of the proteasome. It consists of HslV, the protease, and HslU, the ATPase and chaperone. We have cloned, sequenced and expressed both protein components from the hyperthermophile Thermotoga maritima. T. maritima HslU hydrolyzes a variety of nucleotides in a temperature-dependent manner, with the optimum lying between 75 and 80 degrees C. It is also nucleotide-unspecific for activation of HslV against amidolytic and caseinolytic activity. The Escherichia coli and T. maritima HslU proteins mutually stimulate HslV proteins from both sources, suggesting a conserved activation mechanism. The crystal structure of T. maritima HslV was determined and refined to 2.1-A resolution. The structure of the dodecameric enzyme is well conserved compared to those from E. coli and Haemophilus influenzae. A comparison of known HslV structures confirms the presence of a cation-binding site, although its exact role in the proteolytic mechanism of HslV remains unclear. Amongst factors responsible for the thermostability of T. maritima HslV, extensive ionic interactions/salt-bridge networks, which occur specifically in the T. maritima enzyme in comparison to its mesophilic counterparts, seem to play an important role.

Transkornealer-parakornealer Penetrationsweg f�r lokal applizierte Pharmaka am Auge

PURPOSE

Topically applied drugs can penetrate transcorneally or paracorneally (transsclerally). There are only few studies to demonstrate the relationship of both penetration routes. The immuno-modulator mycophenolate mofetil (MMF), ester and pro-drug of mycophenolic acid (MPA), is a promising substance for such studies.

MATERIAL AND METHODS

Rabbit eyes were treated with different preparations of MMF as a cyclodextrin complex (MM-CD) and as a suspension (MMF-SP) and MPA as a cyclodextrin complex (MPA-CD). The concentrations of both compounds were measured in the cornea, conjunctiva, aqueous humor, vitreous body and iris-ciliary body.

RESULTS

Only MPA is detectable in the cornea after application of MMF-CD and MMF-SP. In the aqueous humor high concentrations of MPA are detectable after 60 min. In the iris-ciliary body both MMF and MPA can be found.

CONCLUSION

The intraocularly detected mycophenolate mofetil represents the paracorneally penetrated fraction. After topical application of mycophenolate mofetil in suitable preparations high concentrations of the active substance can be achieved intraocularly. These favourable pharmacokinetic characteristics are promising for new therapeutic strategies in immune-mediated diseases of the anterior part of the eye.

The twofold difference in adult size between the red junglefowl and White Leghorn chickens is largely explained by a limited number of QTLs

A large intercross between the domestic White Leghorn chicken and the wild ancestor, the red junglefowl, has been used in a Quantitative Trait Loci (QTL) study of growth and egg production. The linkage map based on 105 marker loci was in good agreement with the chicken consensus map. The growth of the 851 F2 individuals was lower than both parental lines prior to 46 days of age and intermediate to the two parental lines thereafter. The QTL analysis of growth traits revealed 13 loci that showed genome-wide significance. The four major growth QTLs explained 50 and 80% of the difference in adult body weight between the founder populations for females and males, respectively. A major QTL for growth, located on chromosome 1 appears to have pleiotropic effects on feed consumption, egg production and behaviour. There was a strong positive correlation between adult body weight and average egg weight. However, three QTLs affecting average egg weight but not body weight were identified. An interesting observation was that the estimated effects for the four major growth QTLs all indicated a codominant inheritance.

Development of protein microarray technology to monitor biomarkers of rheumatoid arthritis disease

Most biological processes are mediated by complex networks of molecular interactions involving proteins. The analysis of protein expression in biological samples is especially important in the identification and monitoring of biomarkers for disease progression and therapeutic endpoints. In this paper, the development of a protein microarray format for multiplexed quantitative analysis of several potential markers for rheumatoid arthritis (RA) is described. Development of a high-performance protein microarray system depends on several key parameters such as surface chemistry, capture agents, immobilization technology, and methods used for signal detection and quantification. Several technical possibilities were investigated and compared: poly-L-lysine versus self-assembled monolayer of octadecyl phosphoric acid ester for surface chemistries; noncontact piezoelectric versus contact printing technology for antibody deposition; CCD camera capture versus fluorescent scanning for image detection; and the concentration of coating antibody. On the basis of reproducibility, signal-to-noise ratio, and sensitivity we have selected self-assembled monolayer, noncontact piezoelectric printer, and high-read-out fluorescence scanning for our microarray format. This format was used to perform multiplexed quantitative analysis of several potential markers of disease progression of rheumatoid arthritis: IL-1beta, IL-6, IL-8, MCP-1, and SAA. Some assays, such as MCP-1, provided a working range that covered physiologically relevant concentrations. Other assays, such as IL-6 and SAA, lacked sensitivity or were too sensitive for measuring biological concentrations, respectively. The results described demonstrate the applicability of protein microarrays to monitor RA markers; however, sandwich assay methodologies need to be further optimized to measure the appropriate biological ranges of these markers on one chip.

Tumour necrosis factor alpha and interleukin 6 gene expression in keratocytes from patients with rheumatoid corneal ulcerations

BACKGROUND/AIMS

Ultrastructural alterations in the stroma adjacent to corneal perforations have previously been reported in patients with longstanding rheumatoid arthritis. Since patients with rheumatoid arthritis often present upregulation of proinflammatory cytokines in serum and in synovial fluid, it was of interest to analyse the gene expression of these cytokines-for example, tumour necrosis factor alpha (TNF-alpha) and interleukin 6 (IL-6), in corneal samples from patients with corneal ulcerations and/or perforations associated with rheumatoid arthritis.

METHODS

Corneal samples from seven patients with corneal ulcerations and/or perforations associated with rheumatoid arthritis were collected in 4% paraformaldehyde in "RNAse-free" conditions. Paraffin sections were fixed on silan coated slides and further analysed by systematic non-radioactive in situ hybridisation, using specific gene probes for TNF-alpha and IL-6 labelled with digoxigenin (DIG). Detection of hybrids was carried out by using a commercially available DIG detection system.

RESULTS

Whereas an extended TNF-alpha gene expression could be clearly observed in the keratocytes surrounding the corneal ulcerations and/or perforations from five of the seven analysed patients, all seven patients presented clearly positive results for an extended IL-6 gene expression in the analysed tissue samples.

CONCLUSIONS

Alterations in corneal cells surrounding ulcerations and/or perforations in patients with rheumatoid arthritis may occur with implication for inflammatory processes. Upregulation of the proinflammatory cytokines TNF-alpha and IL-6 may modify the production of metalloproteinases in the corresponding cells resulting in collagenolytic corneal damage.

Genetic relations of yolk proportion and chick weight with production traits in a White Leghorn line

1. The main purpose of this study was to estimate genetic correlations between yolk proportion, chick weight and production traits using an animal model. 2. Direct-direct genetic correlations were estimated between yolk proportion and age at first egg (-0.34), body weight at 20 (0.10), 40 (0.58) and 60 (0.52) weeks of age, egg number (0.56), egg mass (0.59), feed intake (0.64) and feed conversion (-0.25). 3. Maternal-direct genetic correlations were estimated between chick weight and age at first egg (0.40), body weight at 20 (0.57), 40 (0.66) and 60 (0.56) weeks of age, egg number (-0.50), egg mass (0.21), feed intake (0.45) and feed conversion (0.17), respectively. 4. In conclusion, the results suggest that selection on a higher yolk proportion would not have any unfavourable effects on egg production. Maternal-direct genetic correlations between chick weight and production traits resembled direct-direct genetic correlations between egg weight and production traits found in other studies.

[Antiviral therapy adjustment in corneal recipients using antibody testing in the aqueous humor]

INTRODUCTION

In corneal recipients with herpes infection, acyclovir given for 1 year postoperatively prevents viral reactivation and improves graft outcome. The indication for prophylactic antiviral therapy relies on the preoperative diagnosis of herpes. However, many patients present with corneal scars featuring sequelae of herpes without a proven history of herpes. Here we report the results of a prospective study of anti-herpes simplex virus (anti-HSV) and varicella zoster virus (VZV) antibody testing in the aqueous humor at the time of corneal transplantation to refine the indication of the antiviral treatment.

MATERIAL AND METHODS

The study involved 33 keratitis corneal graft recipients, 21 of whom had documented herpes keratitis. A control group was made with 11 cataract patients. An anterior chamber puncture was performed just before surgery. The micro-ELISA test was done on both aqueous humor and serum, and local anti-HSV or VZV antibody synthesis was acknowledged if the ratio of antibody concentrations was above 4.

RESULTS

Local antibody synthesis to HSV was detected in 22 cases, to VZV in 9 cases, to both HSV and VZV in 6 cases, and no synthesis in 8 cases. The sensitivity of the test was 65% in patients with a documented history of herpes (14 cases out of 21). Among non-herpetic patients, the test was positive in 9 patients, who thus benefited from postoperative antiviral therapy. No viral reactivation was encountered after a minimum follow-up of 1 year.

CONCLUSIONS

Antibody testing in the aqueous humor at the time of keratoplasty is a convenient, inexpensive diagnostic tool in corneal recipients. It provides useful information before prescribing a long and expensive postoperative antiviral therapy.