Bilateral ocular hypertension with rapidly progressive optic neuropathy in a teen.

PURPOSE: We report a rare case of bilateral juvenile open-angle glaucoma (JOAG), with discussion of current understanding of its pathogenesis, differential diagnosis, genetics, and management. The importance of tonometry and dilated fundus examination as essential parts of a complete ocular examination, regardless of patient age, is emphasized. CASE REPORT: A Hispanic female teenager presented for an updated eye examination as a requirement before joining military boot camp. Chief concern was blurry vision at distance, with no other reported ocular or systemic problems. She manifested simple myopia in both eyes and was correctable to 20/20 in each eye with glasses. However, intraocular pressure (IOP) in each eye was measured above 40 mm Hg. Subsequent automated perimetry showed significant visual field defects, and laser polarimetry analysis of the optic nerve fibers corresponded with the visual field loss pattern. Maximal medical therapy was administered to lower the IOP, with minimal success. Subsequent incisional trabeculectomy with topical antimetabolite were performed in both eyes to achieve adequate control of her IOPs. CONCLUSIONS: Juvenile-onset Open Angle Glaucoma (JOAG) has been proposed to be a small subset of Primary Open Angle Glaucoma (POAG) and on a continual spectrum of Primary Open Angle Glaucoma. Because most patients with JOAG are asymptomatic, tonometry and optic nerve analysis are crucial in early detection and, thus, must be performed on all patients, young and old. JOAG has a variable onset, with rapidly progressive neuropathy that does not respond well to medical therapy alone, and surgical intervention is often the eventual treatment of choice. Mutations in the myocillin gene have been strongly linked to the disease. JOAG follows an autosomal dominant inheritance with relatively high penetrance. As such, close monitoring, genetics screening, and/or early medical management to prevent irreversible optic neuropathy and blindness should be considered as well for presymptomatic family members.

Regulation of Ins(3,4,5,6)P(4) signaling by a reversible kinase/phosphatase.

Regulation of Cl(-) channel conductance by Ins(3,4,5,6)P(4) provides receptor-dependent control over salt and fluid secretion, cell volume homeostasis, and electrical excitability of neurones and smooth muscle. Ignorance of how Ins(3,4,5,6)P(4) is synthesized has long hindered our understanding of this signaling pathway. We now show Ins(3,4,5,6)P(4) synthesis by Ins(1,3,4,5,6)P(5) 1-phosphatase activity by an enzyme previously characterized as an Ins(3,4,5,6)P(4) 1-kinase. Rationalization of these phenomena with a ligand binding model unveils Ins(1,3,4)P(3) as not simply an alternative kinase substrate, but also an activator of Ins(1,3,4,5,6)P(5) 1-phosphatase. Stable overexpression of the enzyme in epithelial monolayers verifies its physiological role in elevating Ins(3,4,5,6)P(4) levels and inhibiting secretion. It is exceptional for a single enzyme to catalyze two opposing signaling reactions (1-kinase/1-phosphatase) under physiological conditions. Reciprocal coordination of these opposing reactions offers an alternative to general doctrine that intracellular signals are regulated by integrating multiple, distinct phosphatases and kinases.

A series of 3 cases of corneal abrasion with multiple etiologies.

BACKGROUND: Most corneal abrasions are caused by mechanical injuries affecting the superficial epithelial layer. Although one of the functions of the eyelid is to protect the eye, its reaction time of about 425 msec is slower than many ocular insults; thus, corneal abrasions are among the most commonly occurring eye emergencies. CASE REPORTS: Three cases of corneal abrasions with different etiologies are presented. The first case was a large abrasion of the cornea near the visual axis caused by a wood chip. A metal foreign body with rust was lodged in the cornea from metal grinding in the second case. The third case was iatrongenically induced by an A-scan probe while a fellow student was measuring the axial length of the eye. CONCLUSION: Corneal abrasions are one of the most common ocular conditions presented to eye clinics or emergency departments. Although there are different etiologies of abraded corneal epithelium, current clinical management for most corneal abrasions involves a bandage contact lens, use of topical antibiotics, and cycloplegics. Large and central corneal abrasions, however, warrant a consultation with a corneal specialist.

Paralogous murine Nudt10 and Nudt11 genes have differential expression patterns but encode identical proteins that are physiologically competent diphosphoinositol polyphosphate phosphohydrolases.

We previously described paralogous human genes [NUDT10 and NUDT11 [where NUDT is (nucleoside diphosphate attached moiety 'X')-type motif, also known as the 'nudix'-type motif]] encoding type 3 diphosphoinositol polyphosphate phosphohydrolases (DIPP3) [Hidaka, Caffrey, Hua, Zhang, Falck, Nickel, Carrel, Barnes and Shears (2002) J. Biol. Chem. 277, 32730-32738]. Normally, gene duplication is redundant, and lacks biological significance. Is this true for the DIPP3 genes? We address this question by characterizing highly-conserved murine Nudt10 and Nudt11 homologues of the human genes. Thus these genes must have been duplicated prior to the divergence of primates and sciurognath rodents, approx. 115 million years ago, greatly exceeding the 4 million year half-life for inactivation of redundant paralogues; our data therefore indicate that the DIPP3 duplication is unusual in being physiologically significant. One possible functional consequence is gene neofunctionalization, but we exclude that, since Nudt10 and Nudt11 encode identical proteins. Another possibility is gene subfunctionalization, which we studied by conducting the first quantitative expression analysis of these genes. We demonstrated high Nudt10 expression in liver, kidney and testis; Nudt11 expression is primarily restricted to the brain. This differential, but complementary, expression pattern indicates that subfunctionalization is the evolutionary consequence of DIPP3 gene duplication. Our kinetic data argue that diphosphoinositol polyphosphates are more physiologically relevant substrates for DIPP3 than are either diadenosine hexaphosphate or 5-phosphoribosyl 1-pyrophosphate. Thus the significance of the Nudt10/Nudt11 duplication is specific hydrolysis of diphosphoinositol polyphosphates in a tissue-dependent manner.

An adjacent pair of human NUDT genes on chromosome X are preferentially expressed in testis and encode two new isoforms of diphosphoinositol polyphosphate phosphohydrolase.

Combinatorial expression of the various isoforms of diphosphoinositol synthases and phosphohydrolases determines the rates of phosphorylation/dephosphorylation cycles that have been functionally linked to vesicle trafficking, stress responses, DNA repair, and apoptosis. We now describe two new 19-kDa diphosphoinositol polyphosphate phosphohydrolases (DIPPs), named types 3alpha and 3beta, which possess the canonical Nudix-type catalytic motif flanked on either side by short Gly-rich sequences. The two enzymes differ only in that Pro-89 in the alpha form is replaced by Arg-89 in the beta form, making the latter approximately 2-fold more active in vitro. Another Nudix substrate, diadenosine hexaphosphate, was hydrolyzed less efficiently (k(cat)/K(m) = 0.2 x 10(5) m(-1) s(-1)) compared with diphosphoinositol polyphosphates (k(cat)/K(m) = 2-40 x 10(5) m(-1) s(-1)). Catalytic activity in vivo was established by individual overexpression of the human (h) DIPP3 isoforms in HEK293 cells, which reduced cellular levels of diphosphoinositol polyphosphates by 40-50%. The hDIPP3 mRNA is preferentially expressed in testis, accompanied by relatively weak expression in the brain, contrasting with hDIPP1 and hDIPP2 which are widely expressed. The hDIPP3 genes (NUDT10 encodes hDIPP3alpha; NUDT11 encodes hDIPP3beta) are only 152 kbp apart at p11.22 on chromosome X and probably arose by duplication. Transcription of both genes is inactivated on one of the X chromosomes of human females to maintain appropriate gene dosage. The hDIPP3 pair add tissue-specific diversity to the molecular mechanisms regulating diphosphoinositol polyphosphate turnover.