Untargeted metabolomics in the aqueous humor reveals the involvement of TAAR pathway in glaucoma

Understanding the metabolic dysfunctions and underlying complex pathological mechanisms of neurodegeneration in glaucoma could help discover disease pathways, identify novel biomarkers, and rationalize newer therapeutics. Therefore, we aimed to investigate the local metabolomic alterations in the aqueous humor and plasma of primary glaucomatous patients. This study cohort comprised primary open-angle glaucoma (POAG), primary angle-closure glaucoma (PACG), and cataract control groups. Aqueous humor and plasma samples were collected from patients undergoing trabeculectomy or cataract surgery and subjected to high-resolution mass spectrometry (HRMS) analysis. Spectral information was processed, and the acquired data were subjected to uni-variate as well as multi-variate statistical analyses using MetaboAnalyst ver5.0. To further understand the localized metabolic abnormalities in glaucoma, metabolites affected in aqueous humor were distinguished from metabolites altered in plasma in this study. Nine and twelve metabolites were found to be significantly altered (p < 0.05, variable importance of projection >1 and log2 fold change ≥0.58/≤ -0.58) in the aqueous humor of PACG and POAG patients, respectively. The galactose and amino acid metabolic pathways were locally affected in the PACG and POAG groups, respectively. Based on the observation of the previous findings, gene expression profiles of trace amine-associated receptor-1 (TAAR-1) were studied in rat ocular tissues. The pharmacodynamics of TAAR-1 were explored in rabbits using topical administration of its agonist, β-phenyl-ethylamine (β-PEA). TAAR-1 was expressed in the rat's iris-ciliary body, optic nerve, lens, and cornea. β-PEA elicited a mydriatic response in rabbit eyes, without altering intraocular pressure. Targeted analysis of β-PEA levels in the aqueous humor of POAG patients showed an insignificant elevation. This study provides new insights regarding alterations in both localized and systemic metabolites in primary glaucomatous patients. This study also demonstrated the propensity of β-PEA to cause an adrenergic response through the TAAR-1 pathway.

Variants in myelin regulatory factor (MYRF) cause autosomal dominant and syndromic nanophthalmos in humans and retinal degeneration in mice

Nanophthalmos is a rare, potentially devastating eye condition characterized by small eyes with relatively normal anatomy, a high hyperopic refractive error, and frequent association with angle closure glaucoma and vision loss. The condition constitutes the extreme of hyperopia or farsightedness, a common refractive error that is associated with strabismus and amblyopia in children. NNO1 was the first mapped nanophthalmos locus. We used combined pooled exome sequencing and strong linkage data in the large family used to map this locus to identify a canonical splice site alteration upstream of the last exon of the gene encoding myelin regulatory factor (MYRF c.3376-1G>A), a membrane bound transcription factor that undergoes autoproteolytic cleavage for nuclear localization. This variant produced a stable RNA transcript, leading to a frameshift mutation p.Gly1126Valfs*31 in the C-terminus of the protein. In addition, we identified an early truncating MYRF frameshift mutation, c.769dupC (p.S264QfsX74), in a patient with extreme axial hyperopia and syndromic features. Myrf conditional knockout mice (CKO) developed depigmentation of the retinal pigment epithelium (RPE) and retinal degeneration supporting a role of this gene in retinal and RPE development. Furthermore, we demonstrated the reduced expression of Tmem98, another known nanophthalmos gene, in Myrf CKO mice, and the physical interaction of MYRF with TMEM98. Our study establishes MYRF as a nanophthalmos gene and uncovers a new pathway for eye growth and development.

Oxidative and Anti-Oxidative Stress Markers in Chronic Glaucoma: A Systematic Review and Meta-Analysis

Chronic glaucoma is a multifactorial disease among which oxidative stress may play a major pathophysiological role. We conducted a systematic review and meta-analysis to evaluate the levels of oxidative and antioxidative stress markers in chronic glaucoma compared with a control group. The PubMed, Cochrane Library, Embase and Science Direct databases were searched for studies reporting oxidative and antioxidative stress markers in chronic glaucoma and in healthy controls using the following keywords: “oxidative stress” or “oxidant stress” or “nitrative stress” or “oxidative damage” or “nitrative damage” or “antioxidative stress” or “antioxidant stress” or “antinitrative stress” and “glaucoma”. We stratified our meta-analysis on the type of biomarkers, the type of glaucoma, and the origin of the sample (serum or aqueous humor). We included 22 case-control studies with a total of 2913 patients: 1614 with glaucoma and 1319 healthy controls. We included 12 studies in the meta-analysis on oxidative stress markers and 19 on antioxidative stress markers. We demonstrated an overall increase in oxidative stress markers in glaucoma (effect size = 1.64; 95%CI 1.20–2.09), ranging from an effect size of 1.29 in serum (95%CI 0.84–1.74) to 2.62 in aqueous humor (95%CI 1.60–3.65). Despite a decrease in antioxidative stress marker in serum (effect size = –0.41; 95%CI –0.72 to –0.11), some increased in aqueous humor (superoxide dismutase, effect size = 3.53; 95%CI 1.20–5.85 and glutathione peroxidase, effect size = 6.60; 95%CI 3.88–9.31). The differences in the serum levels of oxidative stress markers between glaucoma patients and controls were significantly higher in primary open angle glaucoma vs primary angle closed glaucoma (effect size = 12.7; 95%CI 8.78–16.6, P < 0.001), and higher in pseudo-exfoliative glaucoma vs primary angle closed glaucoma (effect size = 12.2; 95%CI 8.96–15.5, P < 0.001). In conclusion, oxidative stress increased in glaucoma, both in serum and aqueous humor. Malonyldialdehyde seemed the best biomarkers of oxidative stress in serum. The increase of some antioxidant markers could be a protective response of the eye against oxidative stress.

Targeted overexpression of TGF-α in the corneal epithelium of adult transgenic mice induces changes in anterior segment morphology and activates noncanonical Wnt signaling

PURPOSE

Transforming growth factor-alpha (TGF-α) transduces its signal through the epidermal growth factor receptor and is essential for corneal epithelial homeostasis. Previous studies have demonstrated that overexpression of TGF-α in the developing eye leads to anterior segment dysgenesis. However, the underlying mechanisms remain unclear. Here we examined the effects of TGF-α overexpression on adult ocular surface homeostasis.

METHODS

Binary Tet-On transgenic Krt12(rtTA)/tet-O-TGF-α mice were subjected to doxycycline (Dox) induction to overexpress TGF-α in the corneal epithelium. Intraocular pressure (IOP) was measured by noninvasive tonometry. The enucleated eyes of the experimental mice were subjected to histopathology, immunohistochemistry, and biochemistry examination.

RESULTS

Histologic and immunofluorescent examination showed that double-transgenic mice overexpressing TGF-α manifested peripheral anterior synechiae. Elevation of IOP, activation of glial cells, and loss of retinal ganglion cells were also observed. Quantitative real-time PCR revealed that the expressions of genes (RXRα, PITX2, and FOXC1) related to anterior segment dysgenesis were downregulated. Canonical Wnt signaling was suppressed, whereas noncanonical Wnt ligands (Wnt4 and Wnt5a) were upregulated. Increased myosin light chain phosphorylation suggested that noncanonical Wnt signaling is activated in affected eyes.

CONCLUSIONS

Overexpression of TGF-α in the corneal epithelium induces changes in anterior segment morphology. Corneal endothelial abnormalities are associated with the activation of the noncanonical Wnt and RhoA/ROCK signaling axis, indicating a potential application of RhoA/ROCK inhibitors as a therapeutic strategy for certain types of secondary angle-closure glaucoma.

The evaluation of the oxidative stress parameters in patients with primary angle-closure glaucoma

Objective

To clarify the presence of oxidative stress in patients with primary angle-closure glaucoma (PACG) and to investigate the relationship between oxidative stress and PACG.

Methods

Fifty patients with primary angle-closure glaucoma and fifty healthy controls of matched age and gender were included in the study prospectively. Serum samples were obtained to detect the oxidation degradation products malondialdehyde (MDA), conjugated diene (CD), 4-hydroxynonenal (4-HNE), advanced oxidation protein products (AOPP), protein carbonyl (PC), ischemia-modified albumin (IMA) and 8-hydroxydeoxyguanosin (8-OHdG).

Results

The concentration of MDA and CD in PACG patients was significantly higher than those of the control subjects (P<0.05, P<0.01). The serum 4-HNE concentrations were increased in PACG patients, but the differences with those of the healthy controls were not statistically significant. Compared to normal subjects, there was significant higher in serum AOPP and PC in PACG patients (P<0.01). PACG patients had higher levels of 8-OHdG in serum with respect to the comparative group of normal subjects (P<0.01). When plasma IMA levels in the PACG group were compared with those in the control group, significant increases in IMA were observed in the former (P<0.05).

Conclusions

Our study demonstrated that IMA is a new biomarker available for assessing oxidative stress in PCAG. Oxidative stress is an important risk factor in the development of primary angle-closure glaucoma. Increased levels of oxidative stress products may be associated with primary angle-closure glaucoma.

[The blood-aqueous barrier changes after laser peripheral iridotomy or surgery peripheral iridectomy]

OBJECTIVE

To investigate the ocular blood-aqueous barrier (BAB) alteration after laser peripheral iridotomy (LPI) or surgery peripheral iridectomy (SPI) in patients with primary chronic angle-closure glaucoma (PCACG).

METHODS

This was a clinical randomized controlled trial. Sixty eyes of 60 subjects with early stage of PCACG were randomly received either LPI or SPI and followed up postoperatively at day 3, week 1, 2, 3, and 4. Aqueous flare in anterior chamber was measured by FC-2000 flare-cell photometry, intraocular pressure (IOP) measured by tonometer, central corneal endothelium cell counted by endothelioscopy, peripheral anterior synechiae (PAS) detected by gonioscopy. Data were analyzed by using two-way ANOVA for repeated measures, independent samples t-test, paired t-test, nonparametric test, and Spearman rank correlation test.

RESULTS

On follow-ups of pre-operative and post-operative 3 days, 1 week (w), 2w, 3w and 4w respectively, the mean aqueous flare values for LPI group were (5.47 ± 1.09), (11.96 ± 3.07), (8.08 ± 2.18), (5.68 ± 0.83), (5.80 ± 1.00), (5.69 ± 1.12) PC/ms, and for SPI group were (5.43 ± 1.13), (8.44 ± 3.22), (6.42 ± 1.77), (5.35 ± 0.71), (5.53 ± 1.26), (5.45 ± 1.23) PC/ms. During post-operative 1w the flare values in both LPI and SPI groups were significantly higher than that on pre-operation (t = -12.753, -8.101, P < 0.05; t = -5.971, -3.870;P < 0.05) and LPI group had a significantly higher mean flare value than SPI group (t = 4.329, 3.231;P < 0.05). The IOP spike in LPI group was significantly (χ(2) = 5.079, 4.022, P < 0.05) higher than that in SPI group at week 1 of post-operation. Increased IOP was positively correlated with BAB damage (r = 0.899, 0.833; P < 0.05). The numbers of medications required to maintain IOP ≤ 21 mm Hg (1 mm Hg = 0.133 kPa) at week 4 of post-operation in LPI was significantly (Z = -1.984, P < 0.05) more than that in SPI group. There were no significant differences in central corneal endothelium cell count at week 1 (t = -0.696, 0.008) and in extension of PAS at week 4 (Z = -1.270, -1.490) of post-operation when compared to pre-operation (P > 0.05). No obvious complications occurred in both groups.

CONCLUSIONS

Our results demonstrated that IOP spike in both of LPI and SPI is due, at least in part, to BAB damage, which appears to be more severe in LPI group and can recover within two weeks. PAS progression and central corneal endothelium cell loss are not aggravated in 1 month after operation.

Transgenic mice with ocular overexpression of an adrenomedullin receptor reflect human acute angle-closure glaucoma

Glaucoma, frequently associated with high IOP (intra-ocular pressure), is a leading cause of blindness, characterized by a loss of retinal ganglion cells and the corresponding optic nerve fibres. In the present study, acutely and transiently elevated IOP, characteristic of acute angle-closure glaucoma in humans, was observed in CLR (calcitonin receptor-like receptor) transgenic mice between 1 and 3 months of age. Expression of CLR under the control of a smooth muscle alpha-actin promoter in these mice augmented signalling of the smooth-muscle-relaxing peptide adrenomedullin in the pupillary sphincter muscle and resulted in pupillary palsy. Elevated IOP was prevented in CLR transgenic mice when mated with hemizygote adrenomedullin-deficient mice with up to 50% lower plasma and organ adrenomedullin concentrations. This indicates that endogenous adrenomedullin of iris ciliary body origin causes pupillary palsy and angle closure in CLR transgenic mice overexpressing adrenomedullin receptors in the pupillary sphincter muscle. In human eyes, immunoreactive adrenomedullin has also been detected in the ciliary body. Furthermore, the CLR and RAMP2 (receptor-activity-modifying protein 2), constituting adrenomedullin receptor heterodimers, were identified in the human pupillary sphincter muscle. Thus, in humans, defective regulation of adrenomedullin action in the pupillary sphincter muscle, provoked in the present study in CLR transgenic mice, may cause acute and chronic atony and, thereby, contribute to the development of angle-closure glaucoma. The CLR transgenic mice used in the present study provide a model for acute angle-closure glaucoma.

Acute increase of intraocular pressure releases ATP into the anterior chamber

Throughout the body, mechanical perturbations are transduced into neurochemical signals by the release of ATP from non-neuronal cells. As an increased intraocular pressure (IOP) can initiate mechanical changes, we hypothesized that extracellular levels of ATP might be increased in the anterior chamber of human patients with primary acute angle closure glaucoma (PAACG). ATP levels in aqueous humor samples were determined using the luciferin-luciferase assay. Samples were obtained from 18 controls scheduled for cataract extraction and from 14 subjects with angle closure glaucoma during paracentesis. All subjects with angle closure glaucoma had remarkably elevated levels of ATP in their aqueous humor. The mean ATP concentration was ninefold higher for patients with angle closure glaucoma than for control. The concentration of ATP was correlated with IOP levels, further supporting a causal relationship. ATP levels were not influenced by the duration of the PAACG attack, suggesting the rate of ATP release was sustained. We conclude that increased IOP leads to increased levels of extracellular ATP in the anterior chamber. This elevated ATP may contribute to the extreme pain experienced by subjects with angle closure glaucoma, and may serve as a source of elevated adenosine in the anterior chamber.

Dynamic analysis of dark-light changes of the anterior chamber angle with anterior segment OCT

PURPOSE

To describe the use of anterior segment optical coherence tomography (OCT) in studying the dynamic dark-light changes of the anterior chamber angle.

METHODS

Thirty-seven normal subjects with open angles on dark-room gonioscopy and 18 subjects with narrow angles were analyzed. The dynamic dark-light changes of the anterior-chamber angle were captured with real-time video recording. The angle opening distance (AOD500) and trabecular iris space area (TISA500) of the nasal angle and the pupil diameter in each of the representative serial images were measured. Linear regression analysis was performed to investigate the association between AOD500/TISA500 and pupil diameter. Demographic and biometry measurements associated with the AOD difference (AOD500((light)) - AOD500((dark))) and TISA difference (TISA500((light)) - TISA500((dark))) were analyzed with univariate and multivariate regression models.

RESULTS

The AOD500/TISA500 measured in the light in the open-angle and the narrow-angle groups were 694 +/- 330 microm/0.24 +/- 0.10 mm(2) and 265 +/- 78 microm/0.10 +/- 0.03 mm(2), respectively. These values were significantly greater than the AOD500/TISA500 measured in the dark (492 +/- 265 microm/0.16 +/- 0.08 mm(2) and 119 +/- 82 microm/0.05 +/- 0.04 mm(2), respectively, all with P < 0.001). The ranges of the AOD/TISA difference were 13 to 817 microm/0.011 to 0.154 mm(2), with an average of 180 microm/0.073 mm(2). Multivariate regression analysis identified a positive correlation between anterior chamber depth and the AOD/TISA difference. Fifty eyes showed significant correlations between AOD/TISA and pupil diameter, whereas one eye showed no association. Four eyes in the narrow angle group developed appositional angle closure in the dark.

CONCLUSIONS

The dynamic dark-light changes of the anterior chamber angle can be imaged and analyzed with anterior segment OCT. Although the angle width generally decreased linearly with increasing pupil diameter, the differences of the angle width measured in the dark and in the light varied substantially among individuals.

Disease-related quantitation of TGF-beta3 in human aqueous humor

TGF-beta3 has been implicated in the pathology of ocular diseases, but its concentration in human aqueous humor has never been assessed. In this study, we established an enzyme-linked immunosorbent assay (ELISA) for TGF-beta3 and quantitated it in aqueous humor collected from patients with pseudoexfoliation syndrome (PE), primary open angle glaucoma, chronic angle closure glaucoma and cataract (as the control). To develop the TGF-beta3 ELISA, we screened antibodies to identify the best combination, validated the assay for aqueous humor, and optimized the procedure for preparing activated TGF-beta3. As a result, our ELISA was highly selective and reproducible. Using our ELISA, we discovered a significantly elevated concentration of TGF-beta3 in PE eyes. We also developed new TGF-beta1 and -beta2 ELISAs, and were able, for the first time, to quantitate all the TGF-beta isoforms in the aqueous humor from a single eye, to assess their proportional effects on the pathogenesis of ocular diseases.

Transforming growth factor-beta levels in human aqueous humor of glaucomatous, diabetic and uveitic eyes

Purpose

Transforming growth factor-β₂ is known to be present at elevated levels in the aqueous humor of patients with primary open angle glaucoma (POAG) and diabetes but not in uveitis-related secondary glaucoma. We investigated total TGF-β₂ levels and levels of the active form of TGF-β₂ in the aqueous humor of eyes with different types of glaucoma.

Methods

The concentration of the total and active form of TGF-β₂ was measured in 63 patients with primary open angle glaucoma, neovascular glaucoma complicated with diabetes (NVG), and secondary open angle glaucoma complicated with uveitis (SOAG) using a double antibody 'sandwich-indirect' ELISA method.

Results

The levels of total TGF-β₂ in the aqueous samples of POAG, NVG, and SOAG were elevated. The levels of active TGF-β₂ in the aqueous samples of POAG, and NVG were also elevated, whereas the level of active TGF-β₂ was within the normal range in the aqueous samples of SOAG.

Conclusions

These results suggest that the level of TGF-β₂ may play a role in the pathology of various types of glaucoma.

Iris and trabecular meshwork pigment changes after posterior chamber phakic intraocular lens implantation

PURPOSE

To evaluate the changes in laser iridotomies, intraocular pressure (IOP), angle structures, and pupil diameter after implantable contact lens (ICL) (Version 4 Staar Surgical) implantation in myopic Asian eyes.

SETTING

Department of Ophthalmology, Chung-Ang University Yongsan Hospital, Seoul, Korea.

METHODS

The ICL was implanted in 81 eyes of 43 patients with spherical equivalent greater than -6.00 diopters. Gonioscopy examination was performed 1 day after laser iridotomy and 6 and 12 months after ICL implantation. The changes in laser iridotomy sites, IOP, and pupil diameter were also evaluated.

RESULTS

Ten eyes (12.3%) had occlusion or narrowing of the laser iridotomy sites. The angle width was more than 30 degrees in all cases preoperatively but narrowed to less than 20 degrees in 16 eyes (19.8%) 6 months postoperatively. The mean pigment, measured by the semiquantitative method (grade 0 to 4), was 2.03 in the inferior angle, 0.18 in the nasal angle, 0.12 in the temporal angle, and 0.00 in the superior angle 12 months postoperatively. The pigment in all quadrants increased temporally as a result of the laser iridotomy or iris rubbing by the ICL; however, the pigments absorbed gradually and decreased to values before laser iridotomy 12 months postoperatively. There was a temporary increase in IOP from the instillation of steroid eyedrops 1 week and 1 month postoperatively; IOP returned to the preoperative level and remained there 12 months postoperatively. There was a significant decrease in pupil diameter 1 and 3 months postoperatively; the diameter returned to the preoperative size at 6 and 12 months. Pigment dispersion syndrome and pigmentary glaucoma were not seen.

CONCLUSION

Implantation of the ICL narrowed the angle width but did not increase trabecular pigmentation compared with values after laser iridotomy, indicating ICL implantation is safe regardless of the pigmentary changes in the trabecular meshwork.

Clusterin deficiency in eyes with pseudoexfoliation syndrome may be implicated in the aggregation and deposition of pseudoexfoliative material

PURPOSE

To determine the role of the extracellular chaperone clusterin in the pathophysiology of pseudoexfoliation (PEX) syndrome/glaucoma, which is characterized by the stable deposition of abnormal extracellular fibrillar material in anterior segment tissues.

METHODS

Real-time PCR, in situ hybridization, and immunohistochemistry were applied to analyze the mRNA and protein expression of clusterin in PEX eyes of patients without and with glaucoma and to compare them with eyes of patients with primary open-angle glaucoma and angle-closure glaucoma and with normal control eyes. Aqueous levels of clusterin were determined by Western blot analysis. Real-time PCR and Western blot analysis were used to study the effect of TGF-beta1, which is significantly increased in the aqueous humor of PEX eyes, on clusterin expression by nonpigmented ciliary epithelial cells in vitro.

RESULTS

Clusterin mRNA was ubiquitously expressed in most ocular cells and tissues, particularly in the epithelium of ciliary processes, whereas the protein was mostly located to extracellular structures, such as ocular basement membranes and stromal fibers. Real-time PCR and in situ hybridization displayed significant downregulation of clusterin mRNA in all anterior segment tissues of PEX eyes, irrespective of the presence or type of glaucoma, compared with normal and glaucomatous control eyes, whereas posterior segment tissues did not show any differential expression. A generally decreased immunoreactivity, but a prominent binding of clusterin to all PEX deposits, could be observed in ocular tissues of PEX eyes. Clusterin levels in aqueous humor were significantly reduced in eyes of patients with PEX syndrome compared with normal and glaucomatous control eyes. The expression of clusterin mRNA and protein in nonpigmented ciliary epithelial cells was significantly downregulated by TGF-beta1 in vitro.

CONCLUSIONS

Considering the known role of clusterin as a highly efficient extracellular chaperone, its deficiency in the anterior segment of PEX eyes may promote the stress-induced aggregation and stable deposition of the pathologic extracellular matrix product characteristic of PEX syndrome.

Videoendoscope-Guided Fluorescein-Assisted Vitrectomy for Phakic Malignant Glaucoma

Malignant glaucoma is a rare secondary glaucoma classically occurring after intraocular surgery in eyes with primary angle closure. Pars plana vitrectomy is reserved for the treatment of malignant glaucoma when medical and laser treatment fail. The primary aim of surgery is the removal of the anterior vitreous to reduce resistance to aqueous flow into the anterior chamber. In phakic eyes, conventional pars plana vitrectomy without lens extraction is frequently unsuccessful because of difficulty visualizing the normally transparent anterior vitreous, combined with the technical challenge of removing the anterior vitreous without damaging the crystalline lens. We describe a technique of intraocular, videoendoscope-guided, fluorescein-assisted pars plana vitrectomy that enables direct visualization and thorough removal of the anterior vitreous without the need for lens extraction in prepresbyopic patients without cataract.

Selective Upregulation of the A3 Adenosine Receptor in Eyes with Pseudoexfoliation Syndrome and Glaucoma

PURPOSE

Adenosine is increasingly released in metabolic stress conditions, like hypoxia or ischemia, and regulates many physiologic processes, such as aqueous humor secretion and intraocular pressure, via activation of four adenosine receptors. In the current study, the role of the adenosine system in the pathophysiology of pseudoexfoliation (PEX) syndrome, which is typically associated with anterior chamber hypoxia and elevated intraocular pressure, was examined.

METHODS

RT-PCR, Northern hybridization, in situ hybridization, and immunohistochemistry were applied to analyze the mRNA and protein expression of the adenosine receptor subtypes A1, A2A, A2B, and A3 in anterior segment tissues of PEX eyes, without and with glaucoma, in comparison to eyes with primary open-angle or angle-closure glaucoma and normal control eyes. Real-time PCR was used to study the effect of hypoxia and oxidative stress on adenosine receptor expression by nonpigmented ciliary epithelial cells in vitro. Levels of adenosine and its catabolites inosine, hypoxanthine, and xanthine were measured in cell culture supernatants and aqueous humor samples by HPLC.

RESULTS

All four adenosine receptor subtypes (A2A > A1 > A2B > A3) were coexpressed but differently distributed in the ciliary epithelium of control eyes, with the A3 receptor being localized to the basolateral membrane infoldings of the nonpigmented epithelial cells. A selective, approximately 10-fold upregulation of A3 receptor mRNA and protein was consistently found in the nonpigmented ciliary epithelium of all PEX eyes, with and without glaucoma, compared with the normal and glaucomatous control eyes. Significant upregulation of A3 receptor message in nonpigmented epithelial cells was induced by both hypoxia and oxidative stress in vitro, together with increased levels of inosine, hypoxanthine, and xanthine in the supernatants. Levels of adenosine and its catabolites, however, were not significantly elevated in the aqueous humor of patients with PEX.

CONCLUSIONS

Considering the known role of the A3 adenosine receptor in modulating aqueous humor secretion, its selective, probably hypoxia-induced upregulation in the ciliary epithelium may not only confer cytoprotection but also influence aqueous humor dynamics and may be accessible to therapeutic intervention in patients with PEX.

Altered transcripts expression of matrix metalloproteinases and their tissue inhibitors in tenon capsule of patients with glaucoma

PURPOSE

To determine the transcripts expression of matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) in Tenon capsule of patients with primary glaucoma and non-glaucomatous patients who serve as the control.

PATIENTS AND METHODS

Specimens of Tenon capsule were obtained intraoperatively and evaluated with the reverse transcriptase-polymerase chain reaction method. The transcripts levels of MMP-1, MMP-2, MMP-9, TIMP-1, and TIMP-2 relative to that of glyceraldehyde phosphate dehydrogenase were determined.

RESULTS

The transcripts levels of MMP-1, MMP-2, MMP-9, TIMP-1, and TIMP-2 were not correlated with age in the control group. There were differences in the transcripts expression of MMP-2 (P < 0.001), MMP-9 (P = 0.017), TIMP-1 (P < 0.001), and TIMP-2 (P = 0.001) among the control, primary open angle glaucoma, and primary angle-closure glaucoma groups (Kruscal-Wallis H test). Comparing with the controls, open angle glaucoma had decreased transcripts levels of MMP-2 (P = 0.001) and TIMP-1 (P = 0.006) while angle-closure glaucoma had decreased transcripts levels of MMP-2 (P < 0.001), MMP-9 (P = 0.004), TIMP-1 (P < 0.001), and TIMP-2 (P < 0.001) (Mann-Whitney U tests).

CONCLUSION

The transcripts expression of certain MMPs and TIMPs is altered in Tenon capsule of glaucoma patients, which might result from long-term application of topical glaucoma medications.

Neuronal Nitric Oxide Synthase (nNOS) Positive Retinal Amacrine Cells are Altered in the DBA/2NNia Mouse, a Murine Model for Angle-Closure Glaucoma

PURPOSE

To characterize retinal amacrine cell changes in eyes of DBA/2NNia (DBA) mice that develop an inherited angle-closure glaucoma.

METHODS

DBA and non-glaucomatous C57BL/6J mice of different age groups (2 to 23 months of age) were studied and compared. Morphologic investigations included NADPH-diaphorase staining of retinal whole mounts and fluorescence immunohistochemistry of cryosections with antibodies against neuronal nitric oxide synthase (nNOS), tyrosin hydroxylase (TH), gamma aminobutyric acid (GABA), and vesicular acetylcholine transporter (VAChT).

RESULTS

Immunohistochemistry of amacrine cell subpopulations in the retinae of DBA mice revealed no significant staining differences in the two mouse strains at all ages using antibodies against TH, GABA, and VAChT. However, staining with nNOS and NADPH diaphorase revealed significant differences between the DBA strain and the C57BL/6J mice. With the onset of elevated IOP and glaucoma beginning at around 6 months in the DBA mice, the total number of NOS positive amacrine cells continuously decreased from 1000 cells at 6 months of age down to 480 cells in animals older than 20 months of age, but did not decline in age-matched C57 mouse retinas.

CONCLUSION

We previously described a parafoveal loss of nNOS positive amacrine cells in the monkey glaucoma model. The fact that there is also a significant decrease of nNOS amacrine cells in the glaucomatous mouse eye indicates a specific response of nNOS positive amacrine cells in glaucomatous retinopathy.

Metabotropic glutamate receptors are differentially regulated under elevated intraocular pressure

Glaucoma is a leading cause of blindness, ultimatively resulting in the apoptotic death of retinal ganglion cells. However, molecular mechanisms involved in ganglion cell death are poorly understood. While the involvement of ionotropic glutamate receptors has been extensively studied, virtually nothing is known about its metabotropic counterparts. Here, we compared the retinal gene expression of metabotropic glutamate receptors (mGluR) in eyes with normal and elevated intraocular pressure (IOP) of DBA/2J mice, a model for secondary angle-closure glaucoma using RT-PCR and immunohistochemistry. Elevated IOP in DBA/2J mice significantly increased retinal gene expression of mGluR1a, mGluR2, mGluR4a, mGluR4b, mGluR6 and mGluR7a when compared to C57BL/6 control animals, while mGluR5a/b and mGluR8a were decreased and no difference was observed for mGluR3 and mGluR8b. Specific antibodies detected an increase of mGluR1a and mGluR5a/b in both synaptic layers and in the ganglion cell layer of the retina under elevated IOP. Because ganglion cell death in DBA/2J mice occurs most likely by apoptotic mechanisms, we demonstrated up-regulation of mGluRs in neurons undergoing apoptosis. In summary, we support the idea that the specific gene regulation of mGluRs is a part of the glaucoma-like pathological process that develops in the eyes of DBA/2J mice.

[The expression of Bcl-2, Bcl-xl, Bak and Bax proteins in axons of the optic nerve in closed-angle glaucoma]

PURPOSE

The aim of our study was the evaluation of Bcl-2, Bcl-xl, Bak and Bax immunoexpression in axons of the optic nerve with absolute glaucoma.

MATERIAL AND METHODS

This study was conducted on 19 patients with absolute glaucoma, suffered from severe ophthalmalgia, treated of necessity by enucleation in 1991-2003 in our Department of Ophthalmology. The samples were immuno-stained with antibodies for Bcl-2, Bak, Bax and Bcl-xl protein. The reactions were performed in Labelled Streptavidin Avidin Biotin (LSAB) technique. The evaluation of immuno-staining was calculated as the percentage of cells with positive reaction to the total number of cells encountered in 10 representative fields, by light microscopy using a x 20 objective lens. Scores were based on the following scale: (++), over 50% of the field showing positive immuno-staining, (+) 10-50% with positive immunostaining.

RESULTS

In our study proapoptotic Bak and Bax protein expression was stronger than antiapoptotic Bcl-2, Bcl-xl protein expression; Bak/Bcl-2 (p = 0.008), Bax/Bcl-2 (p = 0.0007), Bak/Bcl-xl (p = 0.0356), Bax/Bcl-xl (p = 0.0077).

CONCLUSIONS

The results of our study demonstrate high proapoptotic trends in axons of the optic nerve in the stage of absolute glaucoma.

[Nitric oxide level in aqueous humor in patients with glaucoma]

PURPOSE

There is increasing evidence suggesting, that nitric oxide may be implicated in the pathogenesis of glaucoma. The aim of the study was to evaluate nitric oxide level in aqueous humor of glaucoma patients.

MATERIAL AND METHODS

The examined group was constituted by 26 persons (13 women and 13 men), aged 60-86 (mean age 70) suffering from glaucoma. In 14 patients glaucoma was classified as POAG and in 12 as PACG. All patients have undergone trabeculectomia. The 14 patients was operated because of age-related cataract (8 women and 6 men), aged 47-82 (mean age 65), constituted a control group. All patients agreed to samples collection. Level of nitric oxide in anterior chamber fluid was assessed using commercial kits based on Griess reaction (R&D) according to manufacturer's instruction. Statistical analysis was performed using U Mann-Whitney test.

RESULTS

The mean level of nitric oxide in aqueous humor was not significantly different between glaucoma and cataract group (p=0.535). The level of NO in humor aqueous was statistically significantly lower in patients with primary open angle glaucoma than in patients with primary angle closure (p=0.022), and than in control group (p=0.053). No statistically significant differences in the level of nitric oxide in humor aqueous between PACG and cataract patients were observed (p=0.365).

Vitreous amino acid concentrations in patients with glaucoma undergoing vitrectomy

OBJECTIVE

To measure vitreous concentrations of glutamate and other amino acids in patients with glaucoma undergoing vitrectomy.

METHODS

Undiluted vitreous samples were collected from patients undergoing vitrectomy at the University of Iowa (Iowa City) between 1997 and 1998 (n = 69). Vitreous concentrations of 16 amino acids, including glutamate, were determined using high-pressure liquid chromatography. Patients with a history of diabetes mellitus were excluded from the analysis. The study group consisted of those with a history of glaucoma (n = 8), and the control group included those with an epiretinal membrane and/or macular hole with no history of glaucoma (n = 17). Comparison of amino acid concentrations between the 2 groups was performed using a multifactor main effects model that adjusted for the effect of 10 selected covariates. Power analysis was done to determine the level of significant difference in amino acid concentrations.

RESULTS

The glaucoma group comprised vitreal specimens from patients with primary open-angle (n = 3) and angle-closure glaucomas that included aqueous misdirection (n = 2), uveitis with secondary angle-closure (n = 2), and Axenfeld Rieger syndrome (n = 1). Indications for vitrectomy in this group included epiretinal membrane, retinal detachment, aqueous misdirection, and uveitis. The control group included specimens from patients with a macular hole (n = 11) and epiretinal membrane (n = 7), with 1 eye having both. Surgical indications in controls were macular hole, retinal detachment, and epiretinal membrane. The mean +/- SD levels of vitreous glutamate, glycine, gamma-aminobutyric acid, and alanine were 6.1 +/- 2.4, 16.3 +/- 7.5, 0.8 +/- 0.3, and 260.5 +/- 101.9 microM, respectively, in glaucoma and 5.2 +/- 2.3, 8.5 +/- 2.5, 0.6 +/- 0.2, and 159.5 +/- 54.9 microM in controls (P >.05 for all). None of the 16 amino acid concentrations measured showed a statistically significant difference between glaucoma and controls (P values between.06 and >.99). A power analysis indicated that a 1.8-fold elevation in the glutamate level was needed to reach significance.

MAIN OUTCOME MEASURES

Vitreous amino acid concentrations.

CONCLUSIONS

None of the 16 amino acids measured, including glutamate, were significantly elevated in the vitreous of glaucomatous eyes compared with controls. Our results are not consistent with the simple hypothesis of glutamate excitotoxicity in glaucoma. Instead, our findings indicate the dynamic nature of extracellular glutamate, whose concentration is dependent on complex mechanisms not yet fully understood. Further studies are needed to fully elucidate the role of glutamate in the pathogenesis of glaucoma.

Vascular endothelial growth factor is increased in aqueous humor of glaucomatous eyes

PURPOSE

To assess the concentrations of vascular endothelial growth factor (VEGF) in aqueous humor in eyes with and without glaucoma.

METHODS

Concentrations of VEGF were measured using a sandwich ELISA kit in aqueous humor aspirates taken during anterior segment surgery from 87 patients, of whom 54 had glaucoma (27 primary open-angle glaucoma, 8 angle-closure glaucoma, 16 exfoliative glaucoma) and 33 had cataract only.

RESULTS

Vascular endothelial growth factor was detected in all samples. The concentration in eyes with cataract only without glaucoma was 102.4 +/- 29.7 pg/mL (mean +/- SD), which was significantly lower than that from eyes with glaucoma (146.7 +/- 51.8 pg/mL). There were no significant differences between primary open-angle glaucoma (140.4 +/- 51.0 pg/mL), angle-closure glaucoma (142.8 +/- 40.2 pg/mL), and exfoliative glaucoma (158.6 +/- 58.9 pg/mL). An unusually high VEGF concentration was detected in one eye with neovascular glaucoma (759 pg/mL) and two eyes with uveitic glaucoma (322 pg/mL). No effect of age, gender, or previous history of medical, laser, or surgical treatment of the aqueous humor VEGF concentration could be detected ( > 0.05). Aqueous humor and plasma VEGF concentrations were measured and compared in 46 patients. The aqueous humor VEGF concentration (144.2 +/- 107.9 pg/mL) was significantly higher ( < 0.01) than the plasma concentration (79.2 +/- 46.1 pg/mL). No significant correlation was found between aqueous humor and plasma VEGF concentrations.

CONCLUSION

Aqueous VEGF concentration is increased in eyes with glaucoma.

Significant variation of the elevated nitric oxide levels in aqueous humor from patients with different types of glaucoma

Though several studies have shown that the biochemical function of nitric oxide (NO) in the eye might play an important role in the regulation of intraocular pressure (IOP), local control of ocular blood flow and loss of retinal ganglion cells by apoptosis, it is unclear whether the role of NO is similar in the pathogenesis of different kinds of glaucoma: primary open-angle glaucoma (POAG), chronic closed-angle glaucoma (CCAG) and neovascular glaucoma (NVG). To further explore this issue, we measured the concentrations of NO in aqueous humor and plasma samples from patients with POAG (n = 31), CCAG (n = 76), NVG (n = 8) and cataract (n = 30). All of the NVG patients suffered from severe proliferative diabetic retinopathy, while other patients were free of any other systemic disease. The NO levels in both aqueous humor and plasma samples were assessed by chemiluminescence assay. We found that the NO levels in aqueous humor samples were greatly varied in patients with POAG (36.2 +/- 3.3 microM), CCAG (47.7 +/- 3.4 microM) and NVG (65.8 +/- 5.4 microM), and all of them were significantly higher than in cataract patients (27.0 +/- 2.9 microM p < 0.05). Except NVG patients whose NO levels in plasma samples were highest (24.1 +/- 3.5 microM) among all groups, the plasma NO levels were not significantly different between the other glaucoma patients and the cataract patients. We therefore concluded that significant variation of the elevated NO levels in aqueous humor samples from the patients with different types of glaucoma may reflect their differences in the pathogenesis.

Slit-lamp needle revision for aqueous misdirection after trabeculectomy

PURPOSE

To describe a slit-lamp needle procedure for the management of aqueous misdirection after trabeculectomy in which more conventional therapies have failed. The pathophysiology of aqueous misdirection and explanation for the efficacy of this procedure are reviewed.

METHODS

Two patients in whom aqueous misdirection developed after trabeculectomy refractory to standard medical and laser therapy underwent transcorneal needling to disrupt the anterior vitreous face and reform the anterior chamber.

RESULTS

In both cases there was immediate resolution of clinical signs, with normalization of intraocular pressure throughout the 9-month follow-up period. One of the two eyes showed a slow but progressive advance in preexisting peripheral anterior synechia; however, intraocular pressure and axial anterior chamber depth remained normal in both eyes.

CONCLUSION

Transcorneal needle disruption of the anterior hyaloid through the peripheral iridectomy was effectively managed two cases of aqueous misdirection. Even if only transiently useful, this simple intervention may serve to minimize corneal damage from iris and lens trauma due to a flat anterior chamber.

Transforming growth factor-beta 2 levels in aqueous humor of glaucomatous eyes

PURPOSE

To determine whether clinical characteristics are correlated with increased levels of transforming growth factor-beta 2 (TGF-beta 2) in aqueous humor in glaucomatous eyes.

METHODS

Aqueous humor samples were collected from 91 glaucomatous eyes. Included were samples from primary open-angle glaucoma (POAG) in 40 eyes, (pseudo)exfoliation syndrome (EXS) in 18 eyes, primary angle-closure glaucoma (PACG) in 26 eyes and uveitis-related secondary glaucoma (SG) in 7 eyes. TGF-beta 2 in aqueous humor was assessed with a specific-capture ELISA.

RESULTS

The mean concentration (+/- standard error) of mature (biologically active) TGF-beta 2 in the aqueous humor of eyes with POAG was 293.6 +/- 33.6 pg/ml, significantly higher than that in eyes with PACG, EXS and SG: 147.5 +/- 28.1, 135.8 +/- 30.2 and 41.0 +/- 10.7 pg/ml, respectively (P = 0.0006, P = 0.0010 and P = 0.0003; analysis of variance). The mean concentration (+/- standard error) of total TGF-beta 2 in the aqueous humor of eyes with POAG was 1647.6 +/- 124.5 pg/ml, not significantly different from that in eyes with PACG, EXS and SG: 1482.9 +/- 148.2, 1442.7 +/- 187.8 and 1929.0 +/- 367.6 pg/ml, respectively. A multivariate analysis using logistic regression showed significant correlations between mature TGF-beta 2 concentration and history of cataract surgery (P = 0.0225) and the use of carbonic anhydrase inhibitors (P = 0.0143).

CONCLUSIONS

Our results indicate that increased levels of TGF-beta 2 may play an important role in the pathogenesis of POAG.

[A clinical investigation on the relationship between nitric oxide and elevation of intraocular pressure in glaucoma]

OBJECTIVE

To investigate the role of nitric oxide (NO) in the process of intraocular pressure (IOP) elevation in glaucoma.

METHODS

The levels of NO in plasma and in aqueous humor which were obtained from 16 patients with acute angle closure glaucoma (10 female, 6 male), 29 cases with cataract (13 female, 16 male) and 30 normal volunteers (13 female, 17 male) were detected by high performance liquid chromatography and expressed with the total NO(2) and NO(3).

RESULTS

It was found that the mean level of NO in the plasma in glaucoma group was (l,390.78 +/- 302.95) ng/L that was significantly lower than that in the normal group (2 969.37 +/- 862.85) ng/L (t = 2.853, P < 0.01). But in cataract group it was (4,234.89 +/- 1,495.23) ng/L that was significantly higher than that in the normal group (t = 4.471, P < 0.01). There was no significant difference in the level of NO in the aqueous humor between glaucoma group (2,052.03 +/- 694.74) ng/L and normal group (1,405.83 +/- 602.70) ng/L (t = l.862, P > 0.05). But in cataract group the mean level of NO (2, 454.67 +/- 655.13) ng/L in the aqueous humor was increased remarkably in comparison with that in the normal group (t = 2.752, P < 0.01). The rate of the mean content of NO in normal aqueous humor and plasma (aqueous/plasma) was 47.3%, and that in cataract group, 57.96% (P > 0.05). But in glaucoma group, the rate was 144.0%.

CONCLUSION

The content of nitric oxide in the plasma and aqueous humor is related to the elevation of IOP in cases with acute angle closure glaucoma.

Hepatocyte growth factor is increased in the aqueous humor of glaucomatous eyes

PURPOSE

To assess the concentrations of hepatocyte growth factor (HGF) in the aqueous humor of eyes with glaucoma compared with control eyes with cataract only.

METHODS

Concentrations of HGF were measured in aqueous humor aspirates taken during anterior segment surgery from 84 patients, of whom 72 had glaucoma (38 cases of primary open-angle glaucoma, 17 angle-closure glaucoma, and 17 exfoliative glaucoma) and 12 had cataract only, using a sandwich enzyme-linked immunosorbent assay kit.

RESULTS

Hepatocyte growth factor was detected in all samples. The concentration in eyes with cataract only was 563.3 +/- 178.8 pg/mL (mean +/- standard deviation), which was significantly lower than that in eyes with glaucoma (967.1 +/- 514.7 pg/mL, P < 0.01). Eyes with exfoliative glaucoma had significantly higher HGF concentrations (1,425.5 +/- 586.7 pg/mL) than did eyes with primary open-angle glaucoma (855.0 +/- 341.5 pg/mL) and angle-closure glaucoma (759.4 +/- 511.4 pg/mL) (P < 0.01). There was no effect of age, sex, or history of medical, laser, or surgical treatment on the aqueous humor HGF concentration (P > 0.05). Aqueous humor and plasma HGF concentrations were measured and compared in 28 patients. The aqueous humor HGF concentration (908 +/- 586.2 pg/mL) was significantly higher (P < 0.01) than the plasma concentration (521.3 +/- 183.1 pg/mL). No significant correlation could be found between aqueous humor and plasma HGF concentrations.

CONCLUSIONS

The relatively high concentration of HGF in human aqueous humor suggests that HGF may play an important role in ocular physiology and disease. The higher concentration in patients with glaucoma may indicate a response to injury.

Elevated nitric oxide level in aqueous humor of patients with acute angle-closure glaucoma

Nitric oxide, a noxious and free-radical gas, plays a key role in vasodilatation, inflammation, immunity, and neurotoxicity. Studies have shown that a recently detected NO synthase inducible isoform, found in astrocytes in the optic nerve heads of glaucoma patients, could stimulate excessive production of NO. The purpose of our study was to elucidate the role of NO production in the pathogenesis of glaucoma. We measured the concentrations of NO in aqueous humor from 11 patients with acute angle-closure glaucoma (AACG) and 14 patients with cataract. All samples were collected from patients who were free of any other systemic disease. Utilizing a chemiluminescence assay, we found that in AACG patients the NO levels in aqueous humor samples (83.2 +/- 6.7 microM) were significantly higher than in cataract patients (27.1 +/- 3.6 microM; p < 0.001). We therefore concluded that excessive NO in AACG patients reflects the degree of ocular impairment demonstrated by concomitant retinal cell and optic nerve cell damage.

Concurrent downregulation of a glutamate transporter and receptor in glaucoma

PURPOSE

Elevated levels of extracellular glutamate have been implicated in the pathophysiology of neuronal loss in both central nervous system and ophthalmic disorders, including glaucoma. This increase in glutamate may result from a failure of glutamate transporters, which are molecules that ordinarily regulate extracellular glutamate. Elevated glutamate levels can also lead to a perturbation in glutamate receptors. The hypothesis for the current study was that glutamate transporters and/or receptors are altered in human glaucoma.

METHODS

Immunohistochemical analyses of human eyes with glaucoma and control eyes were performed to evaluate glutamate receptors and transporters. These molecules were also assayed in rat eyes injected with glial-derived neurotrophic factor (GDNF).

RESULTS

Glaucomatous eyes had decreased levels of both the glutamate transporter, excitatory amino acid transporter (EAAT)-1, and the glutamate receptor subunit N-methyl-D-aspartate (NMDA)-R1. Eyes treated with GDNF had elevated levels of both EAAT1 and NMDAR1.

CONCLUSIONS

The loss of EAAT1 in glaucoma may account for the elevated level of glutamate found in glaucomatous vitreous and lead to a compensatory downregulation of NMDAR1. Inasmuch as GDNF can increase levels of both EAAT1 and NMDAR1, it may be a useful therapeutic approach to restore homeostatic levels of these in glaucoma.

Pars plana vitrectomy during cataract surgery for prevention of aqueous misdirection in high-risk fellow eyes

PURPOSE

To report the use of pars plana vitrectomy as a prophylactic measure during cataract surgery for prevention of aqueous misdirection in high-risk fellow eyes.

METHODS

Chart review of two patients with severe aqueous misdirection in their first eye at the time of cataract surgery that only responded to pars plana vitrectomy.

RESULTS

In both patients, cataract extraction with posterior chamber intraocular lens implantation was initially performed after pars plana vitrectomy, with the creation of hyaloido-capsulo-iridotomy to establish a communication between the vitreous cavity and the anterior chamber.

CONCLUSION

Pars plana vitrectomy as a prophylactic measure during cataract surgery may have a beneficial role in fellow eyes at high risk for developing aqueous misdirection.

Retinal TUNEL-positive cells and high glutamate levels in vitreous humor of mutant quail with a glaucoma-like disorder

PURPOSE

To investigate whether retinal cell death observed in an avian glaucoma-like disorder occurs by apoptosis and whether an increase in excitotoxic amino acid concentration in the vitreous humor is associated temporally with cell death in the retina.

METHODS

Presumptive retinal apoptotic nuclei were identified by histochemical detection of DNA fragmentation (by TdT-dUTP terminal nick-end labeling [TUNEL]), and vitreal concentrations of glutamate and several other amino acids were determined by high-pressure liquid chromatography with fluorometric detection in the al mutant quail (Coturnix coturnix japonica) in which a glaucoma-like disorder develops spontaneously.

RESULTS

TUNEL-labeled nuclei were located mostly in the ganglion cell layer (GCL) in the retina of mutant quails 3 months after hatching. However, labeled nuclei were also observed in the inner and outer nuclear layers. At 7 months, most TUNEL-positive nuclei were detected in the inner nuclear layer, whereas labeled cells in the GCL were reduced in number. No TUNEL-labeled nuclei were detected in the retina of control quails at any age. Vitreal concentrations of glutamate and aspartate were significantly increased in 1-month-old mutant quails compared with control animals. Concentrations decreased at 3 months, and no significant differences were observed between strains at 7 months.

CONCLUSIONS

Presumptive apoptotic cell death is detected from 3 months after hatching in mutant quails and is not restricted to retinal ganglion cells. Cell death appears just after a significant increase in excitotoxic amino acid concentrations in the vitreous humor, suggesting a correlation between both events.

[Determination and significance of catecholamines in aqueous humor, plasma and 24 hour urine of patients with acute angle-closure glaucoma]

OBJECTIVE

To study the functional state of ocular and systemic sympathetic nervous system and the effects of its related neurohumoral factor, catecholamines (CA), on intraocular pressure (IOP) in patients with acute angle-closure glaucoma (AACG).

METHODS

The levels of CA in the aqueous humor, plasma and the total amount of CA in 24 hour urine of cases with AACG during attack stage were determined with fluorometry, and the results were compared to that of patients with senile cataract and normal adults.

RESULTS

The CA levels within aqueous humor and plasma and in 24 hour urine of the patients with AACG during attack stage were elevated obviously as compared with that of the control subjects (P < 0.001), and positively correlated with the level of IOP.

CONCLUSION

During attack stage of AACG, the ocular sympathetic nervous system is highly excited and a large amount of CA is released into the aqueous humor, in the meantime the systemic sympathetic nervous system is also excited and CA is released into the blood circulation, which may play a certain role in the regulation of IOP. Possibly, CA is an important supplemental factor within the attack stage of AACG.

Collagen metabolism in human aqueous humor from primary open-angle glaucoma. Decreased degradation and increased biosynthesis play a role in its pathogenesis

OBJECTIVE

To explore the influence of aqueous humor from patients with glaucoma on collagen turnover.

METHODS

The aqueous humor of patients with primary open-angle glaucoma (POAG), chronic angle-closure glaucoma, congenital glaucoma, neovascular glaucoma, and senile cataract (control group) was analyzed for its capacity to induce fibroblast proliferation, collagen synthesis, collagenolytic activity, and production of tissue inhibitor of metalloproteinase-1. All data were analyzed using the Mann-Whitney U test.

RESULTS

Aqueous humor derived from patients with POAG induced a significant decrease of functional collagenase activity (mean +/- SE, 9.12 +/- 1.33 microgram of degraded collagen per milligram of incubated protein vs 20.94 +/- 4.14 micrograms from the control group, P < .05). The enzymatic activity in the other types of glaucoma was similar to that of controls. The POAG samples had a significantly higher concentration of tissue inhibitor of metalloproteinase-1 (mean +/- SE, 3.11 +/- 0.58 vs 0.91 +/- 0.13 micrograms/mL from controls; P < .05). The amount of immunoreactive tissue inhibitor of metalloproteinase-1 found in the other three groups was not significantly different from the control. Aqueous humor stimulated fibroblast proliferation in all cases, but significant differences were not observed between the POAG samples (mean +/- SE, 20,285 +/- 4642 cpm/mg of incubated protein) and the control group samples (26,550 +/- 3688 cpm/mg of incubated protein). Primary open-angle glaucoma fluids increased collagen synthesis significantly compared with the control group (mean +/- SD, 3352 +/- 630 vs 985 +/- 285, P < .05), and the other groups.

CONCLUSIONS

An increase of collagen synthesis and a decrease of collagen degradation may contribute to an excessive deposit of collagen with loss of the trabecular cells during the development of POAG, and aqueous humor must be considered as a microenvironment that affects the metabolism or function of the trabecular meshwork or both.

[Chemiluminescence and activity of acid phosphatase in the drainage zone of the eye in glaucoma patients]

Ocular drainage zone tissue, obtained during surgery from patients with glaucoma, was examined. Chemiluminescence has revealed changed amplitude of the flash and the value of its total light volume. Increased intensity of peroxide chemiluminescence evidences enhanced processes of lipid peroxidation in the tissue and a reduced antioxidant level. Histochemical study of acid phosphatase has discovered destabilization of lysosomal membranes, more marked during an acute attack of glaucoma.