A matched study of primary scleral buckle placement during repair of posterior segment open globe injuries.

AIMS: To compare the visual and anatomical outcomes of patients who underwent primary scleral buckle (SB) placement during posterior segment open globe repair with matched control patients who did not undergo primary SB placement. METHODS: Patients who underwent open globe repair alone or with SB placement at Duke University Eye Center (November 1994-September 1997) and the Massachusetts Eye and Ear Infirmary (July 1993-July 1997) were identified. 19 open globe patients who received primary SB placement were matched with control patients who did not receive a primary SB based on three important prognostic factors: (1) visual grade; (2) zone of injury; and (3) mechanism of injury. The outcomes of interest were: (1) visual outcome; (2) anatomical outcome; (3) subsequent retinal detachment (RD); and (4) number of subsequent surgeries. RESULTS: Baseline characteristics between the groups were similar. Patients who received primary SB placement had a better final visual grade (p = 0.02), logMAR vision (p = 0.007), and anatomical grade (p = 0.01) compared with control patients. Primary SB patients had an average final vision of 20/270, whereas control patients had an average final vision of hand movement. Primary SB placement also resulted in fewer subsequent RDs (26% versus 53%), but this difference did not reach statistical significance (p = 0.10). There were no complications associated with primary SB placement. CONCLUSION: Primary SB placement during posterior segment open globe repair may decrease the risk of subsequent RD and improve final visual and anatomical outcome.

Hypotony caused by scleral buckle erosion in Marfan syndrome.

PURPOSE: To describe hypotony caused by erosion of the conjunctiva and sclera by a silicone scleral buckle. METHODS: Interventional case report. A 33-year-old man with Marfan syndrome presented with hypotony maculopathy and a collapsed globe 17 months after repair of retinal detachment with a silicone sponge and silicone encircling band. RESULTS: Examination in the operating room revealed extrusion of the buckle through the conjunctiva and full-thickness scleral erosion. The silicone buckle was removed, and the scleral defect was closed with interrupted 8-0 nylon sutures. Postoperative glaucoma was treated with cyclophotocoagulation. Eight months after scleral repair, visual acuity was RE: 20/40, intraocular pressure was 10 mm Hg, and the retina was attached. CONCLUSION: Full-thickness scleral erosion secondary to a silicone exoplant causing hypotony is a rare long-term complication in patients with thin sclera.

Pars plana vitrectomy, subretinal injection of tissue plasminogen activator, and fluid-gas exchange for displacement of thick submacular hemorrhage in age-related macular degeneration.

PURPOSE: To evaluate a new procedure for displacement of large, thick submacular hemorrhage in patients with age-related macular degeneration. METHODS: Retrospective review of 11 eyes of 11 patients with age-related macular degeneration and thick submacular hemorrhage (defined as causing retinal elevation detectable on stereo fundus photographs) treated with vitrectomy, subretinal injection of tissue plasminogen activator (25 or 50 microg), and fluid-gas exchange with postoperative prone positioning. Outcome measures included displacement of hemorrhage from the fovea, best postoperative visual acuity, and final postoperative visual acuity. RESULTS: In the 11 affected eyes of 11 patients (seven men and four women; mean age, 76 years), preoperative visual acuity ranged from 20/200 to hand motions. With surgery, subretinal hemorrhage was displaced from the fovea in all 11 cases. Mean postoperative follow-up was 6.5 months (range, 1 to 15 months). Best postoperative visual acuity varied from 20/30 to 5/200, with improvement in nine (82%) cases and no change in two cases. Eight eyes (73%) measured 20/200 or better, with four of these eyes (36%) 20/80 or better. Final postoperative visual acuity ranged from 20/70 to light perception, with improvement in eight (73%) cases, no change in one case, and worsening in two cases. A statistically significant difference was found between preoperative and best postoperative visual acuity (P =.004) but not between preoperative and final visual acuity (P =.16). Hemorrhage recurred in three (27%) eyes, causing severe visual loss in one eye. CONCLUSIONS: This technique displaces submacular hemorrhage from the fovea and can improve vision in patients with age-related macular degeneration. However, recurrence of hemorrhage occurred in 27% of eyes and caused severe visual loss in one eye. A randomized, prospective clinical trial is necessary to determine the efficacy of this technique in comparison with other proposed treatments.

Management of eyes with both idiopathic macular hole and choroidal neovascularization.

PURPOSE: To describe the characteristics, treatment, and outcome of five eyes with both choroidal neovascularization (CNV) and macular hole. METHODS: Medical records of five patients with both macular hole and CNV were reviewed. RESULTS: All eyes had full-thickness macular holes. Most eyes had atypical-appearing macular holes (subretinal hemorrhage, prominent subretinal fluid, or discoloration at the hole margin) at presentation or subsequently when CNV developed. Fluorescein angiography (FA) confirmed the presence of CNV in each eye. Three eyes underwent combined macular hole repair and CNV removal, and sustained closure of these macular holes was achieved. A fourth eye underwent successful argon laser photocoagulation of extrafoveal CNV, and macular hole surgery was declined. The final eye underwent two macular hole repairs before sustained closure was achieved. Final visual acuity, ranging from 20/100 to hand motions, was limited by macular pathology and/or cataract. CONCLUSIONS: Choroidal neovascularization can occur in association with a macular hole. In eyes with an atypical-appearing macular hole, FA should be obtained to detect CNV. Excision of the CNV can be done safely in conjunction with macular hole surgery. Final visual acuity may be limited by cumulative retinal and retinal pigment epithelium damage, especially in eyes with underlying macular disease.

Catalysis of DNA cleavage and nucleoside triphosphate synthesis by NM23-H2/NDP kinase share an active site that implies a DNA repair function.

NM23/NDP kinases play an important role in development and cancer but their biological function is unknown, despite an intriguing collection of biochemical properties including nucleoside-diphosphate kinase (NDP kinase), DNA binding and transcription, a mutator function, and cleavage of unusually structured DNA by means of a covalent enzyme-DNA complex. To assess the role of the nuclease in human NM23-H2, we sought to identify the amino acid responsible for covalent catalysis. By sequencing a DNA-linked peptide and by site-directed mutagenesis, we identified lysine-12, a phylogenetically conserved residue, as the amino acid forming the covalent complex with DNA. In particular, the epsilon-amino group acts as the critical nucleophile, because substitution with glutamine but not arginine completely abrogated covalent adduct formation and DNA cleavage, whereas the DNA-binding properties remained intact. These findings and chemical modification data suggest that phosphodiester-bond cleavage occurs by a DNA glycosylase/lyase-like mechanism known as the signature of base excision DNA repair nucleases. Involvement of NM23/NDP kinase in a DNA repair pathway would be consistent with its role in normal and tumor cell development. Additionally, lysine-12, which is known in the x-ray crystallographic structure to lie in the catalytic pocket involved in the NDP kinase phosphorylation reaction, was found essential also for the NDP kinase activity of NM23-H2, suggesting that the two catalytic activities of NM23-H2 are fundamentally connected.

Primary scleral buckling in open-globe injury involving the posterior segment.

PURPOSE: To determine whether scleral buckle placement at the time of primary repair of open-globe injury of the posterior segment is beneficial. DESIGN: Retrospective, comparative, nonrandomized interventional study. PARTICIPANTS: One hundred twenty-five open-globe injuries treated at the Duke University Medical Center from June 1980 to May 1997. METHODS: Open-globe injuries were classified with the Open-globe Injury Classification. Eyes that had zone 2 and 3 injuries that had a primary buckle placed were compared with those that did not. MAIN OUTCOME MEASURES: Subsequent retinal detachment, visual outcome, and need for subsequent scleral buckling. RESULTS: The rate of retinal detachment and the visual outcome were similar in the two groups. More than half of those who did not have a primary buckle placed had subsequent scleral buckling surgery. CONCLUSIONS: Many open-globe injuries of the posterior segment require eventual scleral buckle. There may be a role for placement of a scleral buckle at the time of primary repair.

Diagnosis of vitreoretinal adhesions in macular disease with optical coherence tomography.

PURPOSE: To compare the relative incidence of vitreoretinal adhesions associated with partial vitreous separation within the macula diagnosed with optical coherence tomography (OCT) with that of those diagnosed with biomicroscopy. METHODS: The authors obtained linear cross-sectional retinal images using OCT in patients with selected macular diseases. Additional studies included biomicroscopy, fundus photography, fluorescein angiography, and B-scan ultrasonography. RESULTS: Optical coherence tomography was performed on 132 eyes of 119 patients. Vitreoretinal adhesions within the macula were identified using OCT in 39 eyes (30%) with the following diagnoses: idiopathic epiretinal membrane (n = 13), diabetic retinopathy (n = 7), idiopathic macular hole (n = 7), cystoid macular edema (n = 7), and vitreomacular traction syndrome (n = 5). Biomicroscopy identified vitreoretinal adhesions in only 11 eyes (8%). Two distinct vitreoretinal adhesion patterns were identified with OCT, each associated with partial separation of the posterior hyaloid face: focal (n = 25) and multifocal (n = 14). CONCLUSIONS: Optical coherence tomography is more sensitive than biomicroscopy in identifying vitreoretinal adhesions associated with macular disease.

Association of the apolipoprotein E gene with age-related macular degeneration: possible effect modification by family history, age, and gender.

PURPOSE: Age-related macular degeneration (AMD) is a complex disorder affecting older adults in which genetic factors are likely to play a role. It has been previously suggested that the e4 allele of the apolipoprotein E (APOE) gene may have a protective effect on AMD risk and that the e2 allele may increase disease risk. The purpose of our study was to examine whether an independent data set would support the proposed role of APOE in AMD etiology. METHODS: We compared AMD cases (n=230) to controls (n=372) with respect to APOE genotypes using c2 tests and logistic regression analysis. We also conducted separate analyses for familial (n=129) and sporadic (n=101) AMD cases since these groups may have a different disease etiology. RESULTS: We did not find evidence for the risk-increasing effect attributed to the e2 allele in either familial or sporadic AMD. No evidence for a protective effect of the e4 allele was obtained for sporadic AMD. The age- and sex-adjusted odds ratio (OR) for e4 carriers among familial AMD cases compared to controls was 0.66 (95% confidence interval: 0.38-1.12, p=0.13). In the subgroup of individuals younger than 70 years of age, an OR of 0.24 (95% confidence interval: 0.08-0.72, p=0.004) was obtained. CONCLUSIONS: Our data modestly support a protective effect of the APOE-e4 allele on AMD risk, but emphasize the need to investigate more thoroughly whether the effect could be restricted to cases with a family history of AMD and whether it varies across age and sex groups.

Human NM23/nucleoside diphosphate kinase regulates gene expression through DNA binding to nuclease-hypersensitive transcriptional elements.

NM23-H2/NDP kinase B has been identified as a sequence-specific DNA-binding protein with affinity for a nuclease-hypersensitive element of the c-MYC gene promoter (Postel et al., 1993). The ability of Nm23-H2 to activate c-MYC transcription in vitro and in vivo via the same element demonstrates the biological significance of this interaction. Mutational analyses have identified Arg34, Asn69 and Lys135 as critical for DNA binding, but not required for the NDP kinase reaction. However, the catalytically important His118 residue is dispensible for sequence-specific DNA binding, suggesting that sequence-specific DNA recognition and phosphoryl transfer are independent properties. Nm23-H2 also has an activity that cleaves DNA site-specifically, involving a covalent protein-DNA complex. In a DNA sequence-dependent manner, Nm23-H2 recognizes additional target genes for activation, including myeloperoxidase, CD11b, and CCR5, all involved in myeloid-specific differentiation. Moreover, both NM23-H1 and Nm23-H2 bind to nuclease hypersensitive elements in the platelet-derived growth factor PDGF-A gene promoter sequence-specifically, correlating with either positive or negative transcriptional regulation. These data support a model in which NM23/NDP kinase modulates gene expression through DNA binding and subsequent structural transactions.

Cleavage of DNA by human NM23-H2/nucleoside diphosphate kinase involves formation of a covalent protein-DNA complex.

The NM23 gene family in humans is implicated in differentiation and cancer, but the biochemical mechanisms are unknown. Most NM23 proteins have phosphotransferase (nucleoside diphosphate kinase) activity, and the second human isoform, NM23-H2, also binds to a nuclease-hypersensitive c-MYC promoter element through which it activates c-MYC transcription. It is shown here that this DNA binding can result in double-stranded breaks. The DNA breaks occur within repeated sequence elements in the linear nuclease-hypersensitive duplex and leave staggered ends with 5-nucleotide-long 3'-extensions. The enzyme also cleaves supercoiled plasmid DNA to yield nicked circular and unit length linear products. The cleavage reaction requires only NM23-H2, DNA, Mg(2+), and buffer, occurs in the absence of denaturing conditions, and can be reversed by EDTA. The cleaved DNA strands have free 3'-OH groups, and protein is attached to the 5'-phosphoryl ends. Transfer of (32)P radioactivity from DNA to NM23-H2 has been observed, and a covalent polypeptide-DNA complex has been isolated and identified by Western blotting as NM23-H2. Since covalent protein-DNA complexes are known to serve the role of breaking and rejoining DNA strands, the present findings suggest that NM23-H2 is involved in DNA structural transactions necessary for the activity of the c-MYC promoter.

Long-term follow-up of iatrogenic phototoxicity.

OBJECTIVE: To evaluate the outcomes of a group of patients who suffered iatrogenic phototoxic injury. METHODS: The medical records of 24 patients (24 eyes) with iatrogenic phototoxicity from 3 medical centers were reviewed. We report the findings from long-term follow-up of these patients with particular attention to visual outcome, type and duration of procedure, and location of the phototoxic lesion. RESULTS: Phototoxic injury occurred after anterior segment surgery in 20 eyes and after vitrectomy in 4 eyes. The mean duration of surgery was 109 minutes; there was no statistically significant difference in duration between the anterior segment procedures and the vitrectomies. Mean final visual acuity was 20/40 for all cases (range, 20/15 to counting fingers) and 20/25 for all anterior segment cases. In vitrectomized eyes, the mean final visual acuity was 20/900. Phototoxic lesions tended to spare the fovea after anterior segment surgery and involve the foveal center after vitrectomy. CONCLUSIONS: In general, patients who suffer phototoxicity do well, and the prognosis is good for extrafoveal lesions. Foveal injury, which often occurs with vitrectomy, usually leads to a worse visual outcome. The development of choroidal neovascularization may have an effect on the ultimate visual outcome as well.

NM23-NDP kinase.

NM23 belongs to a large family of structurally and functionally conserved proteins consisting of 4-6 identically folded subunits of approximately 16-20 kDa. These oligomeric proteins exhibit nucleoside diphosphate kinase (NDPK) activity that catalyzes nonsubstrate specific conversions of nucleoside diphosphates to nucleoside triphosphates. Many NM23 proteins bind DNA. In vivo, NM23-NDPKs regulate a diverse array of cellular events including growth and development. They are also implicated in the pathogenesis and metastasis of tumors. The mechanism whereby NM23 regulates gene expression is proposed to entail DNA-binding and subsequent alterations in promoter DNA structure. Accordingly, NM23 has the potential to become a useful reagent for gene manipulations.

The etiology and treatment of macular detachment associated with optic nerve pits and related anomalies.

PURPOSE: Up to two thirds of patients with optic disc pits develop a sight-limiting maculopathy. There is confusion regarding the etiology and nature of the maculopathy in these cases. We present 7 cases of serous macular detachment occurring in association with optic pits or related cavitary anomalies and identify a rhegmatogenous etiology. METHODS: We reviewed the records of 7 patients with optic nerve anomalies and macular detachment. Patients were treated with observation, barricade laser, vitrectomy, and/or gas tamponade. RESULTS: Seven patients were noted to have serous macular detachment associated with an optic nerve pit or other cavitary anomaly. A hole or tear in the diaphanous tissue overlying the optic pit was identified in all cases. None of the patients had a posterior vitreous detachment. Two were treated with photocoagulation only, and 5 underwent pars plana vitrectomy with fluid-gas exchange with or without photocoagulation. Pretreatment visual acuity ranged from 20/30 to 6/200. Posttreatment acuity ranged from 20/25 to 20/100. Five of 7 eyes had final acuities of 20/30 or better, and all treated eyes improved. CONCLUSIONS: A tear in the diaphanous tissue overlying the optic nerve pit is responsible for the development of serous macular detachment and is consistent with findings in similar conditions, such as retinal detachment in association with chorioretinal coloboma. These tears may be quite subtle, and careful biomicroscopic examination is required to appreciate them. The treatment of this condition remains controversial. However, because of the relatively poor prognosis, we believe treatment should include the formation of a barricade to fluid movement as well as sealing and relief of traction from the hole. The value of laser treatment may be increased by the early identification of a defect in the diaphanous membrane prior to the development of macular detachment. Consideration of prophylactic laser might then reduce the need for later, more invasive measures, and improve the prognosis.

Results of peripheral laser photocoagulation in pars planitis.

PURPOSE: To determine the effect of peripheral retinal laser photocoagulation (PLP) on visual acuity, intraocular inflammation, and other ocular findings, including retinal neovascularization in eyes with pars planitis. METHODS: A retrospective chart review of eyes with pars planitis that had undergone PLP. RESULTS: Twenty-two eyes in 17 patients with pars planitis had undergone treatment with PLP at 2 centers. The mean age at the time of treatment was 19.3 years. Following treatment, mean follow-up was 16.3 months (range, 6 to 37 months). Mean visual acuity was 20/60 preoperatively and 20/50 postoperatively. This level of improvement was not statistically significant (P > .10), but there was a statistically significant decrease in the use of corticosteroids between the preoperative examination and the last postoperative examination (86% versus 27%, P < .05). There was also a statistically significant decrease in vitritis at the last follow-up (P = .0008) and a decrease in neovascularization of the vitreous base (P = .03) and in clinically apparent cystoid macular edema (P = .02). Epiretinal membranes were noted in 23% of eyes preoperatively and in 45% of eyes postoperatively. Only one of these epiretinal membranes was considered to be visually significant. One eye developed a tonic dilated pupil, which slowly improved. CONCLUSIONS: Although the long-term natural history of clinical findings in pars planitis is not well documented, PLP appears to decrease the need for corticosteroids while stabilizing visual acuity. It also appears to decrease vitreous inflammation. PLP has few complications and should be considered in patients with pars planitis who are unresponsive or have adverse reactions to corticosteroids.

Three different genes encode NM23/nucleoside diphosphate kinases in Xenopus laevis.

Nucleoside diphosphate kinases (NDPKs) catalyse the phosphorylation of nucleoside diphosphates. In mammals, the functional enzyme is a hexamer composed of different amounts of two homologous acidic (A) and basic (B) subunits encoded by separate genes. In prokaryotes and invertebrate eukaryotes, only one cytoplasmic enzyme has been isolated. Other genes encoding chloroplastic and mitochondrial forms as well as related proteins have been cloned. Here, we show that in Xenopus laevis, as in mammals, the cytoplasmic NDPK is encoded by several homologous genes. With Xenopus laevis being a pseudotetraploid species, each monomer is encoded by two genes. The amino acid sequences are very similar, and all the differences concern amino acids located at the outer surface of the hexameric enzyme. The Xenopus genes share 82-87% identity with their human counterparts. Interestingly, in vitro, the Xenopus X1 enzyme binds to a specific nuclease hypersensitive element (NHE) of the human c-myc promoter, as does its human counterpart. X1 also binds to a single-stranded (CT)(n) dinucleotide repeat. The NHE is present in the coding strand of a pyrimidine-rich region of the 3' non-coding sequence of the Xenopus NDPK genes. We propose that NDPK is indeed able to bind to its own mRNA and prevent polyadenylation at the normal position. This could provide an autoregulatory translation mechanism. A phylogenetic tree of the vertebrate NDPK sequences supports the idea that in amphibians, as in mammals, gene duplication has resulted in functional diversification.

Participatory training methods: what does it mean?

PIP: It is widely recognized that education and training hold the key that will allow women to participate in decision-making in their societies and to achieve sustainable development. In 1990, the gender gap in education was officially recognized, and it was agreed that universal access to basic education would occur by the year 2000. Despite progress, this goal will not be met. Thus, women's groups and nongovernmental organizations will have to provide access for women to the information, knowledge, and skills they need, and many agencies have developed training courses and training modules directed towards specific groups of women or used in combination with the transfer of specific technologies. Women's groups are increasingly using participatory education techniques because participation creates the opportunity of facilitating more respectful communication between trainers and trainees. It is not easy, however, to institute a participatory method because trainers must also be able to learn and adjust and because it is very time consuming to "support from behind" instead of "leading from the front." In order to rescue "participation" from the realm of fashionable terms with no basis in reality, it will be necessary to exchange information about experiences with this technique that is demanding but essential for creating the self-esteem that women require in order to assume a full role in society.^ieng

Mutational analysis of NM23-H2/NDP kinase identifies the structural domains critical to recognition of a c-myc regulatory element.

NM23-H2, a presumed regulator of tumor metastasis in humans, is a hexameric protein with both enzymatic (NDP kinase) and regulatory (transcriptional activation) activity. While the structure and catalytic mechanisms have been well characterized, the mode of DNA binding is not known. We examined this latter function in a site-directed mutational study and identified residues and domains essential for the recognition of a c-myc regulatory sequence. Three amino acids, Arg-34, Asn-69, and Lys-135, were found among 30 possibilities to be critical for DNA binding. Two of these, Asn-69 and Lys-135, are not conserved between NM23 variants differing in DNA-binding potential, suggesting that DNA recognition resides partly in nonconserved amino acids. All three DNA-binding defective mutant proteins are active enzymatically and appear to be stable hexamers, suggesting that they perform at the level of DNA recognition and that separate functional domains exist for enzyme catalysis and DNA binding. In the context of the known crystal structure of NM23-H2, the DNA-binding residues are located within distinct structural motifs in the monomer, which are exposed to the surface near the 2-fold axis of adjacent subunits in the hexamer. These findings are explained by a model in which NM23-H2 binds DNA with a combinatorial surface consisting of the "outer" face of the dimer. Chemical crosslinking data support a dimeric DNA-binding mode by NM23-H2.