Genetic heterogeneity of primary open-angle glaucoma in Pakistan

BackgroundGlaucoma is a neurodegenerative ophthalmic disorder and is considered among the leading causes of irreversible blindness. Primary open-angle glaucoma (POAG) is the most common type of glaucoma that affects after 30 years of life, progressing slowly, and manifests as decreased visual acuity leading to blindness if not treated. POAG is genetically heterogeneous, inherited most commonly in autosomal dominant mode. Several genes have been reported for POAG with myocilin (Myoc) being most common. The present study has been conducted to screen 25 POAG families with 2 or more affected members for their association with Myoc and CYP1B1 (the most common gene in primary congenital glaucoma).MethodsAfter approval from Institutional Ethical Review Committee (ERC), 25 POAG families were enrolled from the southern province (Sindh) of Pakistan. Written informed consent was obtained from all participating individuals and diagnosis was confirmed by consultant ophthalmologists using various instruments and means. Venous blood was obtained from affected individuals and their normal family members for DNA extraction and subsequent analysis.ResultsAll samples were initially screened for the Myoc gene followed by CYP1B1. Screening for Myoc revealed one previously reported variant c.144G>T in POAG-06 whereas screening for CYP1B1 in all 25 families showed a novel variant c.649G>A in POAG-02. The pathogenicity of the novel variant was confirmed using various bioinformatics tools.ConclusionThis is the first report of any POAG family found associated with a novel variant in CYP1B1 from the southern province of Pakistan whereas one family found associated with a reported variant in Myoc. The remaining 23 POAG families did not found to be associated with either Myoc or CYP1B1 indicating genetic heterogeneity of the population in this part of the world.     

Common genetic determinants of intraocular pressure and primary open-angle glaucoma

Intraocular pressure (IOP) is a highly heritable risk factor for primary open-angle glaucoma and is the only target for current glaucoma therapy. The genetic factors which determine IOP are largely unknown. We performed a genome-wide association study for IOP in 11,972 participants from 4 independent population-based studies in The Netherlands. We replicated our findings in 7,482 participants from 4 additional cohorts from the UK, Australia, Canada, and the Wellcome Trust Case-Control Consortium 2/Blue Mountains Eye Study. IOP was significantly associated with rs11656696, located in GAS7 at 17p13.1 (p = 1.4×10⁻⁸), and with rs7555523, located in TMCO1 at 1q24.1 (p = 1.6×10⁻⁸). In a meta-analysis of 4 case-control studies (total N = 1,432 glaucoma cases), both variants also showed evidence for association with glaucoma (p = 2.4×10⁻² for rs11656696 and p = 9.1×10⁻⁴ for rs7555523). GAS7 and TMCO1 are highly expressed in the ciliary body and trabecular meshwork as well as in the lamina cribrosa, optic nerve, and retina. Both genes functionally interact with known glaucoma disease genes. These data suggest that we have identified two clinically relevant genes involved in IOP regulation.     

Senescent phenotype of trabecular meshwork cells displays biomarkers in primary open-angle glaucoma

Glaucoma is a major cause of irreversible blindness, affecting more than 70 million individuals worldwide. Elevated intraocular pressure (IOP) is a major risk factor in the development of glaucoma and in the progression of glaucomatous damage. High IOP usually occurs as a result of an increase in aqueous humor outflow resistance in trabecular meshwork (TM). Primary open angle glaucoma (POAG) is characterized by quantifiable parameters including the IOP, the aqueous outflow facility, and geometric measurements of the optic disc and visual defects. Morphological and biochemical analyses of the TM of POAG patients revealed loss of cells, increased accumulation of extracellular matrix (ECM), changes in the cytoskeleton, cellular senescence and the process of subclinical inflammation. Various biochemical and molecular biology biomarkers of TM cells senescence are considered in the article. Oxidative stress is becoming an important factor more likely to be involved in the pathogenesis of POAG. Treatment of TM cells with oxidative stress induced POAG-typical changes like ECM accumulation, cell death, disarrangement of the cytoskeleton, advanced senescence and the release of inflammatory markers. Oxidative stress is able to induce characteristic glaucomatous TM changes and these oxidative stress-induced TM changes can be minimized by the use of antioxidants, such as carnosine-related analogues and IOP-lowering substances. There is evidence demonstrating that carnosine related analogues may have antioxidative capacities, can prevent cellular senescence and the attrition of telomeres during the action of oxidative stress. Prevention of oxidative stress exposure to the TM with N-acetylcarnosine ophthalmic prodrug of carnosine and oral formulation of non-hydrolized carnosine may help to reduce the progression of POAG. The previous work has demonstrated that carnosine is able to reach the TM directly via the transcorneal and systemic pathways of administration with N-acetylcarnosine ophthalmic prodrug and oral formulation of non-hydrolized carnosine. We suggest in this article that dual therapy with N-acetylcarnosine lubricant eye drops, oral formulation of non-hydrolized carnosine combined with anti-glaucoma adrenergic drug may become the first-line therapy in glaucoma due to their efficiency in reducing IOP, prevention and reversal of oxidative stress-induced damages in TM and the low rate of severe side effects during combined treatment.     

The association between Japanese primary open-angle glaucoma and normal tension glaucoma patients and the optineurin gene

Glaucoma represents one of the most common eye diseases and is characterized by progressive loss of visual fields. In the more advanced stages bilateral blindness may result, due to optic nerve atrophy and an excavated optic nerve head. Open-angle glaucoma is one of the main disease subsets, which may be further divided into high tension primary open-angle glaucoma (POAG) and normal tension glaucoma (NTG). Recently, the optineurin (OPTN) gene was identified as a causative factor for NTG. Alterations in this gene were found in Caucasian families with NTG. In particular, c.458G>A, c.691-692insAG and c.1944G>A were shown to be risk factors. Since NTG is reported to be the most common form of glaucoma in Japan, and to identify if the OPTN gene plays a role in POAG, the DNAs from 148 unrelated Japanese patients with NTG, 165 patients with POAG and 196 unrelated controls who were not suffering glaucoma were investigated by appropriate genotyping techniques. No glaucoma-specific mutations were found in the OPTN gene in Japanese glaucoma patients. However, some novel single-nucleotide polymorphisms (SNPs) in the exons and introns are reported in this paper for the first time.S. Tang and Y. Toda contributed to the same degree for this study     

Mitochondrial damage in the trabecular meshwork occurs only in primary open-angle glaucoma and in pseudoexfoliative glaucoma

Background

Open-angle glaucoma appears to be induced by the malfunction of the trabecular meshwork cells due to injury induced by oxidative damage and mitochondrial impairment. Here, we report that, in fact, we have detected mitochondrial damage only in primary open-angle glaucoma and pseudo-exfoliation glaucoma, among several glaucoma types compared.

Methodology/Principal Findings

Mitochondrial damage was evaluated by analyzing the common mitochondrial DNA deletion by real-time PCR in trabecular meshwork specimens collected at surgery from glaucomatous patients and controls. Glaucomatous patients included 38 patients affected by various glaucoma types: primary open-angle, pigmented, juvenile, congenital, pseudoexfoliative, acute, neovascular, and chronic closed-angle glaucoma. As control samples, we used 16 specimens collected from glaucoma-free corneal donors. Only primary open-angle glaucoma (3.0-fold) and pseudoexfoliative glaucoma (6.3-fold) showed significant increases in the amount of mitochondrial DNA deletion. In all other cases, deletion was similar to controls.

Conclusions/Significance

Despite the fact that the trabecular meshwork is the most important tissue in the physiopathology of aqueous humor outflow in all glaucoma types, the present study provides new information regarding basic physiopathology of this tissue: only in primary open-angle and pseudoexfoliative glaucomas oxidative damage arising from mitochondrial failure play a role in the functional decay of trabecular meshwork.     

Changes in nitric oxide in heart of intact and sympathectomized rats of different age

Nitric oxide production in heart tissues of rats of different age in the norm and after pharmacological sympathectomy was studied by electron spin resonance spin-trapping. Rats at the age of 14, 21, 70, and 100 days were used in the experiment. The concentration of nitric oxide produced in rat heart tissues proved to considerably decrease during ontogeny. Pharmacological sympathectomy notably decreased nitric oxide production in the heart in 14-and 21-day-old rats: the nitric oxide concentration in the spin trap as well as the level of R and T conformers of hemoglobin nitrosyl complexes decreased. In 70-day-old rats, pharmacological sympathectomy had no notable effect on the level of nitric oxide-containing paramagnetic complexes.     

Mapping a gene for adult-onset primary open-angle glaucoma to chromosome 3q.

Glaucoma is the third-leading cause of blindness in the world, affecting >13.5 million people. Adult-onset primary open-angle glaucoma (POAG) is the most common form of glaucoma in the United States. We present a family in which adult-onset POAG is inherited as an autosomal dominant trait. Twelve affected family members were identified from 44 at-risk individuals. The disease-causing gene was mapped to chromosome 3q21-24, with analysis of recombinant haplotypes suggesting a total inclusion region of 11.1 cM between markers D3S3637 and D3S1744. This is the first report of mapping of an adult-onset POAG gene to chromosome 3q, gene symbol GLC1C.     

高寒森林倒木在不同分解阶段的质量变化

倒木是高寒森林生态系统重要的碳(C)库和养分库, 其不同分解阶段的质量变化, 是认识倒木分解过程中C和养分释放的重要基础。以一个分解序列的岷江冷杉(Abies faxoniana)倒木为研究对象, 研究了心材、边材和树皮在5个分解阶段的C:N:P化学计量特征, 以及木质素和纤维素含量动态。结果显示: I至III分解阶段, 随着分解程度加深, 树皮C含量升高, 而心材和边材C含量降低, 从IV分解阶段开始倒木各组分C含量均开始显著降低。除III分解阶段的心材外, 倒木各组分N含量总体表现为随着分解程度加深而增加的趋势, 除边材N含量在V分解阶段时显著升高外, 其余组分均未达到显著性水平。心材和树皮P含量表现为先降后升的变化趋势, 最小值分别出现在III和II分解阶段; 边材P含量表现为随着分解程度加深而增加。在同一分解阶段, 树皮相对于边材和心材均具有最低的C:N:P化学计量比, 易分解比例F_m也表明树皮更易于分解。边材在I和II分解阶段的C:N:P化学计量比最高, 心材在III到V分解阶段C:N:P化学计量比最高。心材C:P、树皮和边材的C:N和C:P临界值与N和P的初始值成反比。纤维素含量随着倒木分解而降低, 不同分解阶段的纤维素含量表现为: 心材>边材>树皮; 但木质素含量随着分解程度加深而增加, 表现为: 树皮>边材>心材; 倒木3个组分纤维素含量下降均快于木质素, 此外, IV和V分解阶段的树皮木质素与纤维素比值显著增高, 且一直处于较高水平。统计分析结果表明: 倒木N含量显著影响不同分解阶段木质素和纤维素分解。由生态化学计量学理论推测: 树皮分解前期易受N限制, 整个分解阶段均易受P限制, 心材和边材在整个分解阶段均易受N和P限制。     

Changes in log quality at different decay stages in an alpine forest

倒木是高寒森林生态系统重要的碳(C)库和养分库,其不同分解阶段的质量变化,是认识倒木分解过程中C和养分释放的重要基础。以一个分解序列的岷江冷杉(Abies faxoniana)倒木为研究对象,研究了心材、边材和树皮在5个分解阶段的C:N:P化学计量特征,以及木质素和纤维素含量动态。结果显示:I至III分解阶段,随着分解程度加深,树皮C含量升高,而心材和边材C含量降低,从IV分解阶段开始倒木各组分C含量均开始显著降低。除III分解阶段的心材外,倒木各组分N含量总体表现为随着分解程度加深而增加的趋势,除边材N含量在V分解阶段时显著升高外,其余组分均未达到显著性水平。心材和树皮P含量表现为先降后升的变化趋势,最小值分别出现在III和II分解阶段;边材P含量表现为随着分解程度加深而增加。在同一分解阶段,树皮相对于边材和心材均具有最低的C:N:P化学计量比,易分解比例Fm也表明树皮更易于分解。边材在I和II分解阶段的C:N:P化学计量比最高,心材在III到V分解阶段C:N:P化学计量比最高。心材C:P、树皮和边材的C:N和C:P临界值与N和P的初始值成反比。纤维素含量随着倒木分解而降低,不同分解阶段的纤维素含量表现为:心材>边材>树皮;但木质素含量随着分解程度加深而增加,表现为:树皮>边材>心材;倒木3个组分纤维素含量下降均快于木质素,此外,IV和V分解阶段的树皮木质素与纤维素比值显著增高,且一直处于较高水平。统计分析结果表明:倒木N含量显著影响不同分解阶段木质素和纤维素分解。由生态化学计量学理论推测:树皮分解前期易受N限制,整个分解阶段均易受P限制,心材和边材在整个分解阶段均易受N和P限制。     

Changes in physicochemical properties of waxy corn starches at different stages of harvesting

Starches were isolated from immature waxy corn kernels harvested at 0, 2, 4 and 6 days after optimum stage (DAO) and from mature kernels at 16 DAO. The starch contents showed varied according to genotypes and harvesting stages. The accumulation of starches showed an increasing trend in relation to delayed harvesting time, from the optimum stage until the physiological maturity stage. Among all harvesting stages, medium granules had the highest contribution to the total starch volume (60.8–81.5%), followed by large (5.7–30.1%), and small granules (9.1–15.3%). Average chain length distribution of amylopectin ranged from DP 14.7 to 16.9 for KKU–UB, DP 16.9 to 17.4 for KKU–JD, and DP 5.7 to 30.1 for Violet white. The pasting behaviors of starches were greatly affected by harvesting times. The peak viscosity of starches increased with delayed harvesting until physiological maturity and then decreased until dried kernels at 35 days after pollination.     

Changes in the magnitude and distribution of forces at different Dictyostelium developmental stages

The distribution of forces exerted by migrating Dictyostelium amebae at different developmental stages was measured using traction force microscopy. By using very soft polyacrylamide substrates with a high fluorescent bead density, we could measure stresses as small as 30 Pa. Remarkable differences exist both in term of the magnitude and distribution of forces in the course of development. In the vegetative state, cells present cyclic changes in term of speed and shape between an elongated form and a more rounded one. The forces are larger in this first state, especially when they are symmetrically distributed at the front and rear edge of the cell. Elongated vegetative cells can also present a front-rear asymmetric force distribution with the largest forces in the crescent-shaped rear of the cell (uropod). Pre-aggregating cells, once polarized, only present this last kind of asymmetric distribution with the largest forces in the uropod. Except for speed, no cycle is observed. Neither the force distribution of pre-aggregating cells nor their overall magnitude are modified during chemotaxis, the later being similar to the one of vegetative cells (F(0) approximately 6 nN). On the contrary, both the force distribution and overall magnitude is modified for the fast moving aggregating cells. In particular, these highly elongated cells exert lower forces (F(0) approximately 3 nN). The location of the largest forces in the various stages of the development is consistent with the myosin II localization described in the literature for Dictyostelium (Yumura et al.,1984. J Cell Biol 99:894-899) and is confirmed by preliminary experiments using a GFP-myosin Dictyostelium strain.     

Changes in thymocyte proliferation at different stages of viral leukemogenesis in AKR mice

Proliferation in total populations of thymocytes from control AKR mice or AKR mice injected intrathymically with MCF 69L1 virus was measured by flow cytometry of acridine orange-stained cells. Cell sorting experiments showed that the majority subpopulations of small cortical and medullary thymocytes in control mice were noncycling and were predominantly in the Go phase of the cell cycle. Of the 15 to 20% cycling thymic lymphoblasts, approximately 50% were in the G1 phase, 35% were in the S phase, and 15% were in the G2 + M phases of the cell cycle. Cycling cells appeared to consist of a major subpopulation with low RNA content and a minority subpopulation with high RNA content. In virus-injected mice, no changes in cell cycling were observed at stage I of leukemogenesis (30 to 40 days postinjection), at which time infection of thymocytes by MCF virus is maximum and constant but no clonality is evident. Thus, MCF virus infection of thymocytes per se does not appear to alter cell proliferation. Increased cell cycling and a shift in cell cycle distribution to more cells in G1 was observed at stage II of leukemogenesis (50 to 60 days postinjection), at which time a clonally expanded cell population is known to emerge in thymuses of injected mice. Acridine orange staining resolved these novel cycling cells from subpopulations of normal thymic lymphoblasts on the basis of intermediate RNA content. The transition from stage II to stage III (50 to 60 days postinjection) was accompanied by the outgrowth of a major cycling population with a distinct, often increased, RNA content. As a result, the residual "normal" background of cycling cells often observed in stage II was markedly reduced or completely absent by stage III. Populations of cycling blasts from mice with frank leukemia differed from those at stage III by a variability in mean RNA content and in cell cycle distribution indicative of individual tumor heterogeneity. In addition, thymomas often contained multiple populations of cycling blasts that could be resolved by their discrete RNA distributions. Simultaneous staining of DNA and RNA by acridine orange appears particularly well-suited for studying a heterogeneous population of cycling and noncycling cells represented by mouse thymus. This method has permitted a rapid and quantitative analysis of cell cycle parameters at progressive stages of viral leukemogenesis in AKR mice.     

Association between MTHFR C677T polymorphism and primary open-angle glaucoma: A meta-analysis

Epidemiological studies have evaluated the association between methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and primary open-angle glaucoma (POAG) risk. However, the results remain conflicting. The aim of this study was to investigate the association between MTHFRC677T polymorphism and POAG risk. All genetic association studies on MTHFR C677T polymorphism and POAG were systematically searched by the electronic databases PubMed, Embase and Web of Science. Study selection, data abstraction and study quality evaluation were conducted in duplicate independently. The strength of association between MTHFR C677T polymorphism and POAG was measured by odds ratios (ORs) and 95% confidence intervals (CIs). Publication bias was tested by Begg's funnel plot and Egger's regression test. A total of 10 studies including 1224 cases and 1105 controls were included in our final meta-analysis. There was no evidence of significant association of the overall population (for allelic model: OR = 1.17, 95% CI = 0.94–1.46; for additive model: OR = 1.15, 95% CI = 0.85–1.57; for dominant model: OR = 1.19, 95% CI = 0.92–1.55 and for recessive model: OR = 1.11, 95% CI = 0.83–1.49). Significant associations were found between MTHFR C677T polymorphisms and POAG in allelic model (OR = 1.39, 95% CI = 1.05–1.83) and additive model (OR = 1.88, 95% CI = 1.04–3.43) for population-based (PB) subgroup. This meta-analysis suggested that there were significant associations between MTHFR C677T polymorphism and POAG in allelic model and additive model for PB subgroup which indicated that the T allele or TT genotype might increase the risk of POAG, whereas no evidence of significant association was shown of the overall studied population. However, this conclusion should be interpreted cautiously. More large sample-size and multi-ethnicity studies with well-defined POAG patients and well-study design are needed in the future study.     

Metabolism of nitric oxide and nitrous oxide during nitrification and denitrification in soil at different incubation conditions

Abstract NO production and consumption rates as well as N₂O accumulation rates were measured in a loamy cambisol which was incubated under different conditions (i.e. soil moisture content, addition of nitrogen fertilizer and/or glucose, aerobic or anaerobic gas phase). Inhibition of nitrification with acetylene allowed us to distinguish between nitrification and denitrification as sources of NO and N₂O. Under aerobic conditions untreated soil showed very low release of NO and N₂O but high consumption of NO. Fertilization with NH₄⁺ or urea stimulated both NO and N₂O production by nitrification. Addition of glucose at high soil moisture contents led to increased N₂ and N₂O production by denitrification, but not to increased NO production rates. Anaerobic conditions, however, stimulated both NO and N₂O production by denitrification. The production of NO and N₂O was further stimulated at low moisture contents and after addition of glucose or NO₃⁻. Anaerobic consumption of NO by denitrification followed Michaelis-Menten kinetics and was stimulated by addition of glucose and NO₃⁻. Aerobic consumption of NO followed first-order kinetics up to mixing ratios of at least 14 ppmv NO, was inhibited by autoclaving but not by acetylene, and decreased with increasing soil moisture content. The high NO-consumption activity and the effects of soil moisture on the apparent rates of anaerobic and aerobic production and consumption of NO suggest that diffusional constraints have an important influence on the release of NO, and may be a reason for the different behaviour of NO release vs N₂O release.     

Changes in the nitric oxide level in the rat liver as a response to brain injury

Liver disturbances stimulate inflammatory reaction in the brain but little is known if injury to the brain can significantly influence liver metabolism. This problem is crucial in modern transplantology, as the condition of the donor brain seems to strongly affect the quality (viability) of the graft, which is often obtained from brain-dead donors, usually after traumatic brain injury. Because nitric oxide is one of the significant molecules in brain and liver biology, we examined if brain injury can affect NO level in the liver. Liver samples of Wistar rats were collected and studied with EPR NO-metry to detect NO level changes at different time points after brain injury. Shortly after the trauma, NO level in the liver was similar to the control. However, later there was a significant increase in the NO content in the livers starting from the 2nd day after brain injury and lasting up to the 7th day. It seems that the response to a mechanical brain injury is of the systemic, rather than local character. Therefore brain metabolism disturbances can influence liver metabolism at least by stimulating the organ to produce NO.