Congenital upper eyelid eversion complicated by corneal perforation.
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Corneal Ulcer↗
Biomedical subjects
A A Al-Rajhi
Publications and source records attributed to A A Al-Rajhi.
Fundus albipunctatus and retinitis punctata albescens in a pedigree with an R150Q mutation in RLBP1.
Fundus albipunctatus (FA; OMIM 136880) is a rare form of apparently stationary night blindness characterized by the presence of myriad symmetrical round white dots in the fundus with a greater concentration in the midperiphery. A distantly similar but distinct clinical entity, retinitis punctata albescens (RPA), is also characterized by aggregation of irregular white flecks but is progressive and evolves to generalized atrophy of the retina. We studied 4 consanguineous kindreds diagnosed with FA from Saudi Arabia. Given the substantial phenotypic variation and overlap between different flecked retinal dystrophies, we evaluated all known genes associated with such conditions by both genetic analysis and direct sequencing. In one kindred, KKESH-099, we identified a homozygous R150Q alteration in RLBP1, the gene encoding the cellular retinaldehyde binding protein, associated previously with both recessive retinitis pigmentosa (arRP) and RPA. Examination of several patients aged 3-20 years over a 9-year period presented no evidence for either RP or RPA. In contrast, clinical examination of individuals with the same mutation in their fourth and fifth decade revealed signs consistent with RPA. The data suggest that the R150Q mutation in RLBP1 may result in RPA with slow progression. More importantly, younger individuals diagnosed with the milder disorder FA thought to be stationary may evolve to a more devastating and progressive phenotype.
Adolescent↗
Kinetic analysis of the toxicological effect of tacrine (Cognex) on human retinal acetylcholinesterase activity.
For the first time, kinetic parameters of the effect of tacrine, an anti-cholinesterase inhibitor of therapeutic potential in Alzheimer's disease has been studied on human retinal acetyl-cholinesterase (AChE). Tacrine inhibited the AChE activity in a concentration dependent manner, the IC(50) being about 45 nM. The Michaelis-Menten constant (K(m)) for the hydrolysis of acetylthiocholine iodide was found to be 0.120 mM and this value was increased by 4-52.8% in the presence of tacrine. V(max) was observed to be 2.23 micromol/h per mg protein for the control system, while it was decreased by 14.73-56.25% in the tacrine treated systems. Dixon as well as Lineweaver-Burk plots and their secondary replots indicated that the nature of the inhibition was of the mixed type, i. e. a combination of competitive and noncompetitive inhibition. The values of K(i) and K(I) were estimated to be as 37.76 and 64.36 nM, respectively.
Acetylcholinesterase↗
Thermodynamic analysis of human retinal acetylcholinesterase inhibition using an anti-Alzheimer's drug, tacrine, through the development of a dual substrate and temperature model.
The present study determines the energy parameters, such as the Gibb's free energy change (deltaG), enthalpy change (deltaH), heat of activation (deltaH*), entropy change (deltaS), temperature coefficient (Q10) and activation energy (Ea), of human retinal acetylcholinesterase (AChE, EC 3.1.1.7) inhibition by tacrine. The stereo-frequency collisions factor (PZ, the number of sterically and energetically favorable collisions occurring between tacrine and AChE) was also studied in this investigation. Tacrine significantly increased the value of deltaG, deltaH, deltaH*, Q10, Ea and PZ factor, and decreased the value of deltaS for AChE. Since there is no known report on the inhibition of human retinal AChE by tacrine, these results were compared with the reported values for the energy parameters of camel retinal and chicken brain AChE inhibition by an anti-cancer drug, cyclophosphamide. The uniqueness of this approach lies in the development of the 'dual substrate and dual temperature' model, which may open up a new, more efficient avenue for the study of various enzyme catalyzed reactions.
Acetylcholinesterase↗
Exclusion of AR-CHED from the chromosome 20 region containing the PPMD and AD-CHED loci.
Congenital hereditary endothelial dystrophy (CHED) is a disorder of the corneal endothelium and has been recognized to segregate in families with both autosomal dominant (AD) and autosomal recessive (AR) modes of transmission. AD-CHED has been previously linked to the pericentric region of chromosome 20. Posterior polymorphous dystrophy (PPMD), a corneal endothelial disorder showing phenotypic overlap with CHED, has also been previously genetically mapped to this region. The genetic interval containing AD-CHED is within the larger genetic interval containing the PPMD locus. This study sought to determine whether AR-CHED segregating in a consanguineous Saudi Arabian pedigree is linked to the previously mapped and overlapping loci for AD-CHED and PPMD on the pericentric region of chromosome 20. Forty members of a consanguineous Saudi Arabian pedigree segregating AR-CHED were ascertained. Short tandem-repeat polymorphic markers from the 20 cM interval on chromosome 20 containing both the PPMD and AD-CHED loci were used to genotype these individuals. LOD score analysis of the genotype data with the MENDEL software package utilizing a model of autosomal recessive inheritance with complete penetrance showed exclusion of CHED from the entire PPMD/AD-CHED interval by utilizing overlapping intervals of LOD scores of at least -2. The results obtained demonstrate that AR-CHED is not allelic to either AD-CHED or PPMD, although it has been proposed that AD-CHED may be allelic to PPMD. Thus, there are at least two genes responsible for CHED and PPMD.
Chromosome Mapping↗
Heparin surface-modified intraocular lenses in patients with inactive uveitis or diabetes.
OBJECTIVE: This study aimed to determine whether heparin surface-modified (HSM) intraocular lenses (IOLs) with a hydrophilic surface would reduce cell adherence and other postoperative changes compared with the conventional polymethylmethacrylate (PMMA) IOLs in patients with either diabetes mellitus or inactive uveitis. DESIGN: The study design was a randomized, double-masked, clinical trial. PARTICIPANTS: Twenty-five patients with bilateral cataracts, 14 with inactive anterior uveitis and 11 with diabetes, with an age range of 11 to 81 years (mean, 52.8 years) participated. INTERVENTION: Bilateral cataract extraction with posterior chamber IOL implantation was measured, each patient receiving an HSM lens in one eye and a PMMA lens in the other. Pharmacia one-piece HSM and PMMA IOLs were used. Postoperative ocular changes were evaluated at regular intervals for 24 months in patients with inactive uveitis and for 6 months in patients with diabetes. Patients and physicians alike were unaware of which eye contained which lens until postoperative results were compiled. Records were kept by a study coordinator. MAIN OUTCOME MEASURES: Comparisons of posterior synechiae, IOL cellular deposits, and posterior capsular fibrosis between PMMA and HSM IOLs were measured. RESULTS: Using the chi-square test, no statistically significant difference was found between the HSM and PMMA IOLs in the number of cellular deposits found on the anterior IOL surface, the number of adhesions between the iris and IOL, or the incidence of capsular opacification. CONCLUSION: The HSM and PMMA IOLs showed similar postoperative results in patients with inactive uveitis or diabetes mellitus.
Adolescent↗
Corneal ectasia in vernal keratoconjunctivitis.
The type of corneal ectasia, the presence of breaks in Descemet's membrane, and the success with contact lens wear or penetrating keratoplasty were studied in 61 patients with corneal ectasia and vernal keratoconjunctivitis. There were 53 patients with keratoconus, 5 with pellucid marginal corneal degeneration, 2 with keratoglobus, and 1 with superior corneal thinning. The high rate of hydrops and the corneal ectasia itself may be related to excessive eye rubbing. Success with contact lens wear or penetrating keratoplasty in vernal keratoconjunctivitis patients with keratoconus is less than in patients with keratoconus alone.
Adolescent↗