ABCC5, a gene that influences the anterior chamber depth, is associated with primary angle closure glaucoma.

Anterior chamber depth (ACD) is a key anatomical risk factor for primary angle closure glaucoma (PACG). We conducted a genome-wide association study (GWAS) on ACD to discover novel genes for PACG on a total of 5,308 population-based individuals of Asian descent. Genome-wide significant association was observed at a sequence variant within ABCC5 (rs1401999; per-allele effect size =  -0.045 mm, P = 8.17 × 10(-9)). This locus was associated with an increase in risk of PACG in a separate case-control study of 4,276 PACG cases and 18,801 controls (per-allele OR = 1.13 [95% CI: 1.06-1.22], P = 0.00046). The association was strengthened when a sub-group of controls with open angles were included in the analysis (per-allele OR = 1.30, P = 7.45 × 10(-9); 3,458 cases vs. 3,831 controls). Our findings suggest that the increase in PACG risk could in part be mediated by genetic sequence variants influencing anterior chamber dimensions.

A competitive formation of DNA:RNA hybrid G-quadruplex is responsible to the mitochondrial transcription termination at the DNA replication priming site.

Human mitochondrial DNA contains a distinctive guanine-rich motif denoted conserved sequence block II (CSB II) that stops RNA transcription, producing prematurely terminated transcripts to prime mitochondrial DNA replication. Recently, we reported a general phenomenon that DNA:RNA hybrid G-quadruplexes (HQs) readily form during transcription when the non-template DNA strand is guanine-rich and such HQs in turn regulate transcription. In this work, we show that transcription of mitochondrial DNA leads to the formation of a stable HQ or alternatively an unstable intramolecular DNA G-quadruplex (DQ) at the CSB II. The HQ is the dominant species and contributes to the majority of the premature transcription termination. Manipulating the stability of the DQ has little effect on the termination even in the absence of HQ; however, abolishing the formation of HQs by preventing the participation of either DNA or RNA abolishes the vast majority of the termination. These results demonstrate that the type of G-quadruplexes (HQ or DQ) is a crucial determinant in directing the transcription termination at the CSB II and suggest a potential functionality of the co-transcriptionally formed HQ in DNA replication initiation. They also suggest that the competition/conversion between an HQ and a DQ may regulate the function of a G-quadruplex-forming sequence.

Telomere- and telomerase-interacting protein that unfolds telomere G-quadruplex and promotes telomere extension in mammalian cells.

Telomere extension by telomerase is essential for chromosome stability and cell vitality. Here, we report the identification of a splice variant of mammalian heterogeneous nuclear ribonucleoprotein A2 (hnRNP A2), hnRNP A2*, which binds telomeric DNA and telomerase in vitro. hnRNP A2* colocalizes with telomerase in Cajal bodies and at telomeres. In vitro assays show that hnRNP A2* actively unfolds telomeric G-quadruplex DNA, exposes 5 nt of the 3' telomere tail and substantially enhances the catalytic activity and processivity of telomerase. The expression level of hnRNP A2* in tissues positively correlates with telomerase activity, and overexpression of hnRNP A2* leads to telomere elongation in vivo. Thus, hnRNP A2* plays a positive role in unfolding telomere G-quadruplexes and in enhancing telomere extension by telomerase.

Formation of DNA:RNA hybrid G-quadruplex in bacterial cells and its dominance over the intramolecular DNA G-quadruplex in mediating transcription termination.

DNA with four guanine tracts can fold into G-quadruplexes that are targets of transcription regulation. We recently found that hybrid DNA:RNA G-quadruplexes (HQs) can form during in vitro transcription. However, it is unclear whether they can form in cells. Evidence is presented supporting their formation in plasmids in bacterial cells. The formation of the HQs is indicated by a unique pattern of prematurely terminated transcripts under two conditions where the RNA transcripts do or do not participate in G-quadruplex assembly and further supported by a number of chemical and biochemical analysis. HQs dominate over the intramolecular DNA G-quadruplexes (DQ) in mediating the transcription termination when both structures are able to form. These findings provide the first evidence of HQ formation in cells and suggest that the competition/conversion between HQ and DQ may regulate transcription and serve as drug target in pharmaceutical applications.

Formation of DNA:RNA hybrid G-quadruplexes of two G-quartet layers in transcription: expansion of the prevalence and diversity of G-quadruplexes in genomes.

G-quadruplexes are implicated in important cellular processes. Previous studies mostly focused on intramolecular G-quadruplexes of three or more G-quartets. Those composed of two G-quartets were only shown to form in single-stranded oligonucleotides. On the basis of electrophoresis, DMS footprinting, fluorescence labeling, and photo-cross-linking, we detected the formation of DNA:RNA hybrid G-quadruplexes (HQs) of two G-quartets during the transcription of DNA duplexes. These HQs have a lifetime on the minute scale and are stabilized by a stabilizing ligand. They are far shorter-lived than the HQs of three G-quartets, which last for hours. The occurrence of putative formation motifs of such HQs shows a transcription-dependent strand-biased selection, thus supporting their formation and function in genomes. They are present in almost all human genes in large amounts. We speculate that the two-G-quartet HQs may be a distinct type of G-quadruplexes that may play a role in timely responsive processes and for purposes of fine-tuning.

Differential associations of myopia with major age-related eye diseases: the Singapore Indian Eye Study.

PURPOSE: To determine the associations of myopia and axial length (AL) with major age-related eye diseases, including age-related macular degeneration (AMD), diabetic retinopathy (DR), age-related cataract, and primary open-angle glaucoma (POAG). DESIGN: Population-based, cross-sectional study. PARTICIPANTS: A total of 3400 Indians (75.6% response rate) aged 40 to 84 years in Singapore. METHODS: Refractive error was determined by subjective refraction, and AL was determined by noncontact partial coherence laser interferometry. Age-related macular degeneration and DR were defined from retinal photographs according to the Wisconsin Age-Related Maculopathy Grading System and Airlie House classification system, respectively. Age-related cataract was diagnosed clinically using the Lens Opacity Classification System (LOCS) III system. Glaucoma was defined according to International Society for Geographical and Epidemiological Ophthalmology criteria. MAIN OUTCOME MEASURES: Age-related macular degeneration, DR, age-related cataract, and POAG. RESULTS: Myopic eyes (spherical equivalent [SE] <-0.5 diopter [D]) were less likely to have AMD (early plus late AMD) (odds ratio [OR], 0.45; 95% confidence interval [CI], 0.25-0.79) or DR (OR, 0.68; 95% CI, 0.46-0.98) compared with emmetropic eyes; each millimeter increase in AL was associated with a lower prevalence of AMD (OR, 0.76; 95% CI, 0.65-0.89) and DR (OR, 0.73; 95% CI, 0.63-0.86). Myopic eyes were more likely to have nuclear (OR, 1.57; 95% CI, 1.13-2.20) and posterior subcapsular (OR, 1.73; 95% CI, 1.10-2.72) cataract, but not cortical cataract (P = 0.64); each millimeter increase in AL was associated with a higher prevalence of posterior subcapsular cataract (PSC) (OR, 1.29; 95% CI, 1.07-1.55), but not nuclear (P = 0.77) or cortical (P = 0.39) cataract. Eyes with high myopia (SE <-6.0 D) were more likely to have POAG (OR, 5.90; 95% CI, 2.68-12.97); each millimeter increase in AL was associated with a higher prevalence of POAG (OR, 1.43; 95% CI, 1.13-1.80). CONCLUSIONS: Myopic eyes are less likely to have AMD and DR but more likely to have nuclear cataract, PSC, and POAG. The associations of myopia with AMD, DR, and POAG are mostly explained by longer AL. However, the association between myopia and nuclear cataract is explained by lens refraction rather than AL.

Neuroprotective effect of mesenchymal stem cell-derived extracellular vesicles on optic nerve injury in chronic ocular hypertension.

Mesenchymal stem cells have neuroprotective effects that limit damage to the retina and photoreceptors, and which may be mediated by extracellular vesicles (or exosomes) released by mesenchymal stem cells. To investigate the neuroprotective effect of extracellular vesicles derived from umbilical cord mesenchymal stem cells on glaucoma, we established rat models of chronic ocular hypertension by injecting conjunctival fibroblasts into the anterior chamber to mimic optic nerve injury caused by glaucoma. One week after injury, extracellular vesicles derived from umbilical cord-derived mesenchymal stem cells were injected into the vitreous cavity. We found that extracellular vesicles derived from mesenchymal stem cells substantially reduced retinal damage, increased the number of retinal ganglion cells, and inhibited the activation of caspase-3. These findings suggest that mesenchymal stem cell-derived extracellular vesicles can help alleviate optic nerve injury caused by chronic ocular hypertension, and this effect is achieved by inhibiting cell apoptosis.

Safety profile of 0.0015% tafluprost eye drops in China: a post-marketing observational study.

AIM: To investigate the treatment pattern and safety of tafluprost for glaucoma and ocular hypertension (OH) in clinical practice in China. METHODS: This post-marketing observational study included patients who received tafluprost to lower intraocular pressure (IOP) within 30d between September 2017 and March 2020 in 20 hospitals in China. Adverse drug reactions (ADRs) during tafluprost treatment and within 30d after the treatment were collected. RESULTS: A total of 2544 patients were included in this study, of them 58.5% (1488/2544) had primary open angle glaucoma (POAG), 21.9% (556/2544) had OH and 19.7% (500/2544) used tafluprost for other reasons. Of 359 ADRs occurred in 10.1% (258/2544) patients, and no serious adverse event occurred. The most common ADR was conjunctival hyperemia (128 ADRs in 124 patients, 4.9%). Totally 1670 participants (65.6%) combined tafluprost with carbonic anhydrase inhibitors (CAIs; 37.1%, 620/1670), sympathomimetics (33.5%, 559/1670), ß-blockers (33.2%, 555/1670), other prostaglandin analogs (PGAs; 15.6%, 260/1670) and other eye drops (15.1%, 253/1670). The highest incidence of conjunctival hyperemia was noted in patients who received tafluprost in combination with other PGAs (23 ADRs in 23 patients, 8.8%, 23/260) and the lowest was in combination with CAIs (16 ADRs in 16 patients, 2.6%, 16/620). Tafluprost was applied in primary angle-closure glaucoma (41.6%, 208/500), after glaucoma surgery (17.8%, 89/500) and after non-glaucoma surgery (15.8%, 79/500). CONCLUSION: Tafluprost is safe for POAG and OH, and tolerable when combined with other eye drops and under various clinical circumstances.

Determinants of corneal biomechanical properties in an adult Chinese population.

PURPOSE: To investigate variations in corneal hysteresis (CH) and corneal resistance factor (CRF) and their ocular and systemic associations in Chinese adults. DESIGN: Population-based, cross-sectional study. PARTICIPANTS: We included 1136 subjects of Chinese origin from an ongoing population-based study. METHODS: All subjects in this population-based study underwent a standardized ocular examination including keratometry (corneal radius of curvature), intraocular pressure (IOP) measurement with Goldmann applanation tonometry, central corneal thickness (CCT), and axial length (AL) assessments. The CH and CRF were measured with the Ocular Response Analyzer. Participants underwent a detailed interview and laboratory investigations that included estimation of nonfasting serum glucose, glycosylated hemoglobin, and lipid profile. MAIN OUTCOME MEASURES: We assessed CH, CRF, and their associations with demographic, ocular, and systemic factors. RESULTS: The mean age of study subjects was 55.3±8.4 years and 51.2% were females. The mean CH and CRF were 10.6±1.5 and 10.1±1.6 mmHg, respectively. Women had higher mean CH (10.8 vs 10.4 mmHg; P<0.001) and CRF (10.4 vs. 9.8 mmHg; P<0.001) than men. After adjusting for age, gender, IOP, CCT, keratometry, AL, and diabetes, CH was negatively associated with age (ß = -0.034; P<0.001), IOP (ß = -0.037; P = 0.01), corneal radius of curvature (ß = -0.963; P<0.001), and AL (ß = -0.106; P = 0.001); and positively associated with female gender (ß = 0.308; P<0.001) and CCT (ß = 0.020; P<0.001). The CRF showed a negative association with age (ß = -0.023; P<0.001) and corneal radius of curvature (ß = -0.771; P<0.001), and was positively associated with female gender (ß = 0.368; P<0.001), IOP (ß = 0.134; P<0.001) and CCT (ß = 0.024; P<0.001). Subjects with diabetes had a higher CH (ß = 0.324; P<0.001) and CRF (ß = 0.396; P = 0.002) compared with those without diabetes. CONCLUSIONS: With advancing age, the CH and CRF in adult Chinese decreased. Women and subjects with diabetes had greater CH and CRF. Corneal biomechanical properties of hysteresis and resistance factor are significantly influenced by IOP, CCT, corneal radius of curvature, and AL.

[The diagnostic value of double-balloon enteroscopy in 67 cases with obscure abdominal pain].

OBJECTIVE: To evaluate the diagnostic valve of double balloon enteroscopy in patients with obscure abdominal pain and analyze the etiology of chronic abdominal pain resulted from enteral diseases. METHODS: Sixty-seven cases with chronic abdominal pain underwent a previous negative gastroscopy, colonoscopy, gastrointestinal barium, B ultrasound and electrocardiogram were received double balloon enteroscopy during June 2005 to June 2008. RESULTS: Thirty-six of 67 patients was done by enteroscopy via anus, and 19 cases via oral, and 12 cases via both anus and oral. The lesions were found in 41 of the 67 patients, with overall diagnostic yield of 61.19%. Among 41 cases of abdominal pain resulted from small bowel diseases, Crohn's disease were found in 15 cases (36.59%), non-specific small enteritis in 10 cases (24.39%), tumors in 8 cases (19.51%), other enteral diseases in 8 cases (19.51%). CONCLUSIONS: Double balloon enteroscopy was a diagnostic modality with a high diagnostic value for obscure abdominal pain resulted from small bowel diseases. The most common causes of obscure abdominal pain were Crohn's disease, non-specific small enteritis and tumors.

[Therapeutic effect of laser photocoagulation of ciliary processes in aphakic glaucoma].

OBJECTIVE: To evaluate the therapeutic effect of laser photocoagulation of ciliary processes after pars plana vitrectomy in aphakic glaucoma. METHODS: Twenty patients (20 eyes) of aphakic glaucoma underwent vitrectomy plus laser treatment. During the surgery, after conventional 3-incision pars plana vitrectomy, a probe of semi-conductor diode laser (532 nm) was inserted through the sclera incision, the ciliary processes were then photocoagulated under direct visualization for 180 degree range. Before and after the surgery, the visual acuity, the intraocular pressure (IOP) as well as the outer appearance of the anterior segment were evaluated. The mean follow-up period was 13 months. RESULTS: The IOP at the last visit was (21.35 +/-2.52) mmHg, which was significantly lower than that before the surgery [(39.75 +/-6.27) mmHg, P=0.000]. Atrophy of the ciliary processes was observed 1-3 months after the surgery. CONCLUSION: Pars plana vitrectomy combined with laser coagulation of ciliary processes reduces the IOP in patients with aphakic glaucoma effectively.

[Effect of porous polyethylene channel implants on volume reconstruction of large orbital wall fractures evaluated by computed tomography measurement].

OBJECTIVE: To assess the clinical effectiveness of porous polyethylene medpor channel implants (MCI) to restore orbital volume in repairing orbital wall fractures, evaluated by computed tomography (CT) and volume measurement program. METHODS: Sixteen patients with unilateral large orbital fractures were included in this study. Computed tomography (CT) scans were used to obtain computer-based orbital volume measurement to assess the change in orbital volume pre- and post-operatively. Pre- and post-operative enophthalmos were measured using a Hertel exophthalmometer. The average time interval between injury and surgery was (17.4+/-10.0) days, and the mean follow-up period was 9 months. RESULTS: Postoperative CT scan showed that most of the MCI to be well positioned. The orbital volume of the injured orbit was significantly increased [mean: (28.16+/-4.32) cm3] as compared with unaffected orbit preoperatively (t=3.044, P<0.01). There was no statistical difference in orbital volume between the injured and normal orbits after orbital reconstruction (t=0.069, P>0.05). The orbital volume change after reconstructive surgery was significantly positively correlated with the decrease of enophthalmos (r=0.715, P<0.01). In order to resolve 2 mm enophthalmos, more than 2.86 cm3 orbital volume augmentation is recommended. CONCLUSIONS: Orbital volume measurement by CT scan is useful in the post-traumatic evaluation of severity of orbital fractures, and it can help predict the degree of late enophthalmos. Orbital reconstruction with the MCI, when indicated, is recommended.

[Dynamic changes of tissue inhibitors of metalloproteinases in the rabbit iris and aqueous humor after lens mechanical injury].

OBJECTIVE: To investigate dynamic changes of expression of tissue inhibitors of metalloproteinases (TIMPs) in the rabbit iris and aqueous humor after the lens mechanical injury. METHODS: Rabbit lens was mechanically injured by a needle through the limbus. Eyes were enucleated on the 1st, 3rd, 7th and 15th day after injury, the aqueous humor was collected and the iris was isolated. The activity of two main TIMPs (TIMP-1 and TIMP-2) in the aqueous humor and the iris was assessed by reverse zymography assay while the activity of matrix metalloproteinase-2 (MMP-2) was analyzed by zymography assay. RESULTS: In the healthy and uninjured rabbit eye, neither TIMP-1 nor TIMP-2 was detected in the aqueous humor or in the iris. In the iris of the injured eye, the activity of TIMP-1 and TIMP-2 was increased significantly 1 day after the injury (P < 0.05), the activity of MMP-2 was inhibited. In the aqueous humor of the injured eye, the activity of TIMP-1 and -2 increased significantly (P < 0.05) 1 day after the injury and the activity of MMP-2 was not detectable. The activity of TIMP-1 and -2 decreased afterwards and no significant difference was detected between the injured eyes and the control eyes 7 days after the injury (P value was 0.097 and 0.777, respectively), while the activity of MMP-2 was increased gradually. CONCLUSION: TIMPs are involved in the acute inflammation process after the lens injury, which may play an important role in the inhibition of inflammation and in the wound healing.

[Prevention of oxidative cataract by PD150606 - an inhibitor of calpains].

OBJECTIVE: To observe oxidative cataract inhibition of PD150606 by studying the opacity of the lens, the variation of protein and cells, and by further studying the role of calpains in the mechanism of oxidative cataract. METHODS: Rat lenses were cultured in vitro with H(2)O(2) and PD150606. The lenses were observed under the microscope. Simultaneously, photograph analysis was performed in order to detect the variation of opacity; the proportion of WSP was determined by the method of Lowry; the number of apoptotic lens epithelial cells (LEC) was measured by flow cytometry; the expression of Caspase 3 in LEC was determined by SAS-PAGE electrophoresis and immunoblotting. RESULTS: Opacity of lens was enhanced in 24 hours when cultured with H(2)O(2) and PD150606. There were significant differences of relative gray scale between H(2)O(2)-induced and control group at 6, 12 and 24 hours (P < 0.05), significant differences of the proportion of WSP between H(2)O(2)-induced and control group at 12 and 24 hours (P < 0.01), significant differences of the number of apoptotic LEC at 6, 12 and 24 hours (P < 0.01) and significant differences of expression of Caspase 3 at 6, 12 and 24 hours (P = 0.000, 0.005, 0.004). CONCLUSION: PD150606, an inhibitor of calpain, can inhibit H(2)O(2)-induced opacity of lens, proteolysis and apoptosis of LEC partially. The activated calpains can induce degradation of crystallins and apoptosis of LEC, which may play a role in the mechanism of oxidative cataract. Caspase 3-dependent pathway may contribute to apoptosis of LEC induced by calpains.

[A quantitative study on early changes in rabbit lens capsule epithelium induced by low power density microwave radiation].

OBJECTIVE: To test the safety of guidelines for limiting exposure to low power level microwave radiation and to try to explore the mechanisms of early damages induced by such radiation in rabbit lens capsule epithelial cells, using flow cytometry as a quantitative method of evaluation of these damages. METHODS: The rabbit eyes were exposed to 5 mW/cm(2) (group I) and 10 mW/cm(2) (group II) power densities of microwave for 3 h. Annexin V-PI two-color flow cytometry was used to detect the changes of rabbits lens epithelial cells, apoptosis cells and secondary necrotic cells after radiation. The other eyes served as self-controls. RESULTS: In group I, the percentage of early apoptosis cells in the experimental eyes was significantly greater than that of the controls (P < 0.01), whereas no significantly difference in the percentage of secondary necrotic cells could be observed (P > 0.05). In group II, there was no significant difference between the percentage of early apoptosis cells in experimental eyes and the controls (P > 0.05), whereas the percentage of secondary necrotic cells in the experimental eyes was significantly greater than that of the controls (P < 0.05). The percentage of secondary necrotic cells (16.2 +/- 5.6)% in group II is greater than that in group I (10.3 +/- 6.8)% (P < 0.05), though there is no significant difference in the percentage of early apoptosis cells between these two groups (P > 0.05). CONCLUSION: Low power density of microwave radiation (5 mW/cm(2) and 10 mW/cm(2)) can induce irreversible damage of rabbit lens epithelial cells in a dose-dependent manner. Therefore, the safety dosage criterion of microwave exposure needs further investigation.

[Treatment of open angle glaucoma with deep sclerectomy combined with laser trabecular puncture].

OBJECTIVE: To study the effect of deep sclerectomy combined with laser trabecular puncture for the treatment of open angle glaucoma (OAG). METHODS: Deep sclerectomy was performed in 32 eyes of 32 patients with moderate to advanced stages of OAG. After the exposure of external wall of Schlemm's canal and the remaining trabecula, the intraocular optic fiber of diode laser photocoagulator was directed to the trabecula-limbus near the anterior edge of the scleral spur. Two or three punctures, approximately 0.5 mm in diameter, were performed with laser beam under direct visualization until aqueous humor was extravasated slowly. The scleral flap was closed with one or two sutures. Postoperative observation included intraocular pressure (IOP), intraocular tissue reaction, the appearance of filtering bleb, gonioscopy and ultrasound biomicroscopy. The follow-up period was 4 to 24 months (7.94 +/- 6.20) months. RESULTS: The anterior chamber was recovered shortly after the operation and the visual acuity remained the same in all eyes. At the end of follow-up period, the postoperative IOP (14.86 +/- 4.15) mm Hg was lower than the preoperative IOP (29.68 +/- 5.76) mm Hg, the difference was statistically significant (t = 7.415, P < 0.001). Diffuse and obvious filtering blebs were found in all eyes after the operation, including 27 functional blebs and 5 blebs that disappeared 2 to 3 months later. Iris was burned slightly in 2 cases, pigment was released and appeared in the anterior chamber temporarily. No laser injury occurred in the cornea and the lens. High IOP was found in 2 cases after long-term follow-up and could be controlled by antiglaucoma medication. CONCLUSIONS: Deep sclerectomy with laser trabecular puncture can effectively reduce the IOP, without the occurrence of serious complications that commonly seen after the trabeculectomy. It is an effective surgical method for the treatment of OAG.

[Expression and modulation of basic fibroblast growth factor in bovine lens epithelial cells].

OBJECTIVE: To evaluate the expression of basic fibroblast growth factor (bFGF) in bovine lens epithelial cells (BLEC), the effects of fetal bovine serum on the expression of bFGF and to explore the effect of breakdown of blood-aqueous barrier on the expression of bFGF after cataract surgery. METHODS: BLEC were isolated and cultured. Western blot and immunohistochemistry method were used to determine the expression of bFGF in these cells. The dose effects (0.2%, 1.0%, 10.0% fetal bovine serum) and time effects (4, 8, 12, 24 h) of 10.0% fetal bovine serum on the expression of bFGF in BLEC were estimated by Western blot analysis. RESULTS: Immunocytochemical study revealed that the cytoplasm of BLEC could be stained positively by the anti-bFGF antibodies. Western blot analysis revealed the presence of bFGF with a molecular weight of 18 000. The expression of bFGF was upregulated in a dose-dependent and time-dependent manner by fetal bovine serum. There was statistically significant difference among the control group and the fetal bovine serum treated group (P < 0.05). CONCLUSIONS: BLEC express relatively low molecular weight bFGF. Fetal bovine serum can upregulate the expression of bFGF in the BLEC. Breakdown of blood-aqueous barrier after cataract surgery can stimulate the expression of bFGF in lens epithelial cells through increasing the serum level in the aqueous humor.

Effect of cAMP on short-circuit current in isolated human ciliary body.

BACKGROUND: Cyclic adenosine monophosphate (cAMP) could activate chloride channels in bovine ciliary body and trigger an increase in the ionic current (short-circuit current, Isc) across the ciliary processes in pigs. The purpose of this study was to investigate how cAMP modulates Isc in isolated human ciliary processes and the possible involvement of chloride transport across the tissue in cAMP-induced Isc change. METHODS: In an Ussing-type chamber system, the Isc changes induced by the cAMP analogue 8-bromo-cAMP and an adenylyl cyclase activator forskolin in isolated human ciliary processes were assessed. The involvement of Cl(-) component in the bath solution was investigated. The effect of Cl(-) channel (10 µmol/L niflumic acid and 1 mmol/L 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS)), K(+) channel (10 mmol/L tetraethylammonium chloride (TEA)), or Na(+) channel blockers (1 mmol/L amiloride) on 8-bromo-cAMP-induced Isc change was also studied. RESULTS: Dose-dependently, 8-bromo-cAMP (10 nmol/L-30 µmol/L) or forskolin (10 nmol/L-3 µmol/L) increased Isc across the ciliary processes with an increase in negative potential difference on the non-pigmented epithelium (NPE) side of the tissue. Isc increase induced by 8-bromo-cAMP was more pronounced when the drug was applied on the NPE side than on the pigmented epithelium side. When the tissue was bathed in low Cl(-) solutions, the Isc increase was significantly inhibited. Finally, niflumic acid and DIDS, but not TEA or amiloride, significantly prevented the Isc increase induced by 8-bromo-cAMP. CONCLUSIONS: cAMP stimulates stroma-to-aqueous anionic transport in isolated human ciliary processes. Chloride is likely to be among the ions, the transportation of which across the tissue is triggered by cAMP, suggesting the potential role of cAMP in the process of aqueous humor formation in human eyes.

Lack of association between primary angle-closure glaucoma susceptibility loci and the ocular biometric parameters anterior chamber depth and axial length.

PURPOSE: Three susceptibility loci for primary angle-closure glaucoma (PACG) were recently identified: PLEKHA7 rs11024102, COL11A1 rs3753841, and rs1015213 located in the intergenic region between PCMTD1 and ST18. The purpose of this study was to investigate the associations of these loci with the ocular biometric parameters anterior chamber depth (ACD) and axial length (AL). METHODS: Genotype and ocular biometric data were available for four population-based studies, including three from Singapore (Singapore Chinese Eye Study, Singapore Malay Eye Study, and Singapore Indian Eye Study) and one from China (Beijing Eye Study), exceeding 7000 participants. ACD and AL were measured using the IOLMaster for the Singapore cohorts and optical low-coherence reflectometry (Lenstar 900 Optical Biometer) for the Beijing cohort. Five readings were obtained for each participant and the average was computed. Analysis excluded any eye that was pseudophakic or aphakic. RESULTS: ACD measurements and genotype data of the three loci were available for 7245, 7243, and 7239 subjects, respectively. We noted nominal evidence of association between single nucleotide polymorphism (SNP) rs1015213 (PCMTD1-ST18) and a shallower ACD when all data were meta-analyzed (ß = -0.033, P = 0.021). When multiple testing was considered, the observation was nonsignificant. There was no association between ACD and rs11024102 (PLEKHA7) or rs3753841 (COL11A1). We did not observe significant associations between AL and any of the three SNPs. CONCLUSIONS: The lack of association between the PACG susceptibility loci with ACD or AL suggests that predilection to PACG may be mediated by factors other than shallow anterior chamber or short eyeball length.

Expression of nitric oxide synthase and guanylate cyclase in the human ciliary body and trabecular meshwork.

BACKGROUND: The role played by the nitric oxide (NO) signaling pathway in the aqueous humor dynamics is still unclear. This study was designed to investigate the expression and distribution of NO synthase (NOS) isoforms and guanylate cyclase (GC) in human ciliary body, trabecular meshwork and the Schlemm's canal. METHODS: Twelve eyes after corneal transplantation were used. Expression of three NOS isoforms (i.e. neuronal NOS (nNOS), inducible NOS (iNOS) and endothelial NOS (eNOS)) and GC were assessed in 10 eyes by immunohistochemical staining using monoclonal or polyclonal antibody of NOS and GC. Ciliary bodies were dissected free and the total proteins were extracted. Western blotting was performed to confirm the protein expression of 3 NOS isoforms and GC. RESULTS: Expression of 3 NOS isoforms and GC were observed in the ciliary epithelium, ciliary muscle, trabecular meshwork and the endothelium of the Schlemm's canal. Immunoreactivity of nNOS was detected mainly along the apical cytoplasmic junction of the non-pigmented epithelium (NPE) and pigmented epithelial (PE) cells. Protein expressions of 3 NOS isoforms and GC were confirmed in isolated human ciliary body by Western blotting. CONCLUSIONS: The expression of NOS isoforms and GC in human ciliary body suggest the possible involvement of NO and cyclic guanosine monophosphate (cyclic GMP, cGMP) signaling pathway in the ciliary body, and may play a role in both processes of aqueous humor formation and drainage.