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PubMed2003

Retinal growth hormone in the chick embryo.

The presence of GH and GH mRNA in the eyes of embryonic chicks is controversial and has, therefore, been further examined. In this study, GH cDNAs identical in size and sequence to the full-length pituitary transcript were generated by RT-PCR from mRNA extracted from the neural retinas of embryonic day (ED) 7 chick embryo eyes. GH immunoreactivity in the neural retina of embryos was primarily associated with proteins of 15 and 16 kDa, whereas only trace amounts of monomer (22-25 kDa) GH, the most abundant form in the pituitary gland, were present. GH immunoreactivity was also present in the vitreous humor, although this was associated only with the 15-kDa protein. After hatch, retinal proteins with GH immunoreactivity of 15 and 16 kDa were present neonatally but not after 42 d of age. The GH immunoreactivity in the neural retina of ED8 embryos was widespread, although GH staining was particularly abundant in retinal ganglion cells (RGCs). Full-length GH mRNA was similarly located, by in situ hybridization, throughout the neural retina and concentrated in cells in the RGC layer. The neural retina is also a site of GH action because 10-6 m chicken GH greatly increased (4- to 5-fold) the content of IGF-1 mRNA in 48-h cultured ED8 neural retinas. These results demonstrate the presence of full-length GH mRNA in the neural retina of chick embryos, in which GH immunoreactivity is primarily associated with RGCs and submonomer GH proteins of 15-16 kDa. These results also demonstrate GH action in the neural retina of embryos and suggest hitherto unsuspected roles for GH in retinal development and/or ocular function.

Amino Acid Sequence↗
PubMed2001

A family with von Hippel-Lindau disease revealed by pheochromocytoma.

Von Hippel-Lindau (VHL) disease is an inherited neoplastic disease characterized by a predisposition to develop retinal angiomas, central nervous system hemangioblastomas, renal cell carcinomas, pancreatic cysts and pheochromocytomas. Recently, we encountered three members of the same family who each had both VHL disease and pheochromocytoma. As in all three patients we suspected pheochromocytoma, the diagnosis of VHL disease should be considered. The possible presence of VHL disease was initially investigated in all three patients based on the presence of pheochromocytoma. A mutational analysis of the VHL gene revealed the presence of a missense mutation, consisting of a G to A transversion, at nucleotide 713 in all three patients. This germline point mutation in the VHL gene is often detected in type 2 VHL disease with pheochromocytoma. Genetic analysis seems to be useful for early detection of VHL disease, even when the formal criteria for diagnosis of this disease are lacking.

Adrenal Gland Neoplasms↗
PubMed2006

Evidence from in vivo imaging that synaptogenesis guides the growth and branching of axonal arbors by two distinct mechanisms.

To explore the relationship between axon arbor growth and synaptogenesis, developing retinal ganglion cell (RGC) axon arbors in zebrafish optic tectum were imaged in vivo at high temporal and spatial resolution using two-photon microscopy. Individual RGC axons were dually labeled by expression of a cytosolic red fluorescent protein (DsRed Express) to mark arbor structure and a fusion of the synaptic vesicle protein synaptophysin with green fluorescent protein (Syp:GFP) to mark presynaptic vesicles. Analysis of time-lapse sequences acquired at 10 min intervals revealed unexpectedly rapid kinetics of both axon branch and vesicle cluster turnover. Nascent axonal branches exhibited short average lifetimes of 19 min, and only 17% of newly extended axonal processes persisted for periods exceeding 3 h. The majority (70%) of Syp:GFP puncta formed on newly extended axonal processes. Syp:GFP puncta also exhibited short average lifetimes of 30 min, and only 34% of puncta were stabilized for periods exceeding 3 h. Moreover, strongly correlated dynamics of Syp:GFP puncta and branch structure suggest that synaptogenesis exerts strong influences on both the extension and the selective stabilization of nascent branches. First, new branches form almost exclusively at newly formed Syp:GFP puncta. Second, stabilized nascent branches invariably bear Syp:GFP puncta, and the detailed dynamics of branch retraction suggest strongly that nascent synapses can act at branch tips to arrest retraction. These observations thus provide evidence that synaptogenesis guides axon arbor growth by first promoting initial branch extension and second by selective branch stabilization.

Aging↗
PubMed1988

Retinoblastoma cells in tissue culture.

This review summarizes and discusses research on retinoblastoma (Rb) cells in tissue culture. Retinoblastoma is an intraocular tumor of early childhood which is believed to originate from the primitive multipotential neuroectoderm of the optic cup region. The application of tissue culture techniques to the study of Rb cells permits detailed studies of the biology of this tumor. Classic studies have primarily focussed on growth and metastatic potential of Rb cells. Y-79 Rb cells, for example, have a short doubling time in vitro as well as aggressively growing in the anterior chambers of athymic 'nude' mice. Such active growth may result from secretion of a Retinoblastoma Derived Growth Factor (RDGF) by the cells. Several natural agents have now been shown to halt Rb cell growth in vitro. Among these are the fatty acid, butyrate, and two retinoids: retinol and retinoic acid. Interestingly, the retinoids have different mechanisms of action. Cultured Y-79 and WERI cells appear to be multipotential in that they exhibit both neuronal- and glial-like characteristics. Natural agents such as cyclic AMP and butyrate can induce the cells to differentiate along either neuronal or glial cell lines as assessed morphologically and immunocytochemically. Of interest is that combination of agents such as butyrate and laminin, an extracellular attachment protein, yield totally different morphologies, in this case, pigment epithelial in nature. Tissue culture studies thus not only show the primitive, multipotential nature of the Rb cells but their great plasticity as well. Such studies are also useful in elucidating the multiple factors (e.g., substrata and soluble agents) which code for normal retinal development from embryo to adult.

Culture Techniques↗
PubMed1996

Ocular phenotypes associated with two mutations (R121W, C126X) in the Norrie disease gene.

PURPOSE: To describe the ocular phenotypes associated with 2 mutations in the Norrie disease gene including a manifesting carrier. METHODS: Ophthalmological examinations were performed in 2 affected males and one manifesting carrier. Genomic DNA was analyzed by direct sequencing of the Norrie disease gene. RESULTS: Family I: A 29-year-old male had the right eye enucleated at the age of 3 years. His left eye showed severe temporal dragging of the retina and central scars. Visual acuity was 20/300. DNA analysis revealed a C-to-T transition of the first nucleotide in codon 121 predicting the replacement of arginine-121 by tryptophan (R121W). Both the mother and maternal grandmother carry the same mutation in heterozygous form. Family 2: A 3-month-old boy presented with severe temporal dragging of the retina on both eyes and subsequently developed retinal detachment. Visual acuity was limited to light perception. His mother's left eye was amaurotic and phthitic. Her right eye showed severe retinal dragging, visual acuity was reduced to 20/60. DNA analysis revealed a T-to-A transversion of the third nucleotide in codon 126 creating a stop codon (C126X). The mother and maternal grandmother were carriers. CONCLUSION: Mutations in the Norrie disease gene can lead to retinal malformations of variable severity both in hemizygous males and manifesting carriers.

Adult↗
PubMed1988

Successful treatment of advanced retinopathy of prematurity.

Thirty-nine eyes of 20 premature infants, mean birthweight 922 g, mean gestational age 27 weeks, with active retinopathy of prematurity (ROP), were treated. Thirty-one eyes with stage 3+ ROP and 180 degrees to 360 degrees of preretinal neovascularization received cryotherapy to ablate the zone of peripheral avascular retina. All underwent complete regression of active disease. Eight of these eyes subsequently developed retinal detachments due to ongoing vitreous traction. One detachment was inoperable. Six eyes were successfully reattached following scleral buckling surgery. One of these six redetached and became inoperable after 20 months. Pars plicata vitrectomy was not successful in reattaching the eighth case. Twenty-eight of these 31 eyes retain useful visual acuity with follow-up of 15 to 70 months (mean 41 months). There have been no complications resulting from cryotherapy. Eight other eyes with stage 4 ROP (traction retinal detachment) were treated with cryotherapy and scleral buckling surgery. All were initially reattached, but ongoing vitreoretinal traction caused redetachment in five. One was inoperable. "Open sky" vitrectomy was successful in reattaching three of the other four. Of the six cases that remained reattached with follow-up of 6 to 51 months, only two retain useful vision.

Cryosurgery↗
PubMedDate not supplied

Retinoblastoma in an eye with features of Coats' disease.

A 44-month-old girl developed retinal detachment with extensive telangiectasia and "light bulb" aneurysms suggestive of Coats' disease. However, underlying and within the retina was diffuse retinoblastoma. Diffuse infiltrative retinoblastoma can manifest features of Coats' disease and could lead to diagnostic confusion.

Child, Preschool↗
PubMedDate not supplied

Ruptured globe 10 years after radial keratotomy.

PURPOSE: To report 3 cases (3 eyes) of globe rupture following blunt trauma 10 to 13 years after radial keratotomy. METHODS: Cases of traumatic ruptured globe after radial keratotomy were reviewed from a tertiary eye care center. One eye underwent therapeutic penetrating keratoplasty, the second was treated with a bandage contact lens, and the third developed retinal detachment leading to phthisis bulbi. RESULTS: Ruptured globes occurred through the keratotomy incision during activities of daily living (1 eye), assault (1 eye), and sports (1 eye). Two eyes regained a visual acuity of 20/30 or better; 1 eye was lost. CONCLUSION: Traumatic rupture of the cornea can occur more than 10 years after radial keratotomy.

Adult↗
PubMed2003

Management of macular pucker.

OBJECTIVE: To document the outcome of macular pucker surgery in terms of improvement of visual acuity. DESIGN: Interventional quasi experimental study. SETTING: Ophthalmology Department, Civil Hospital, Karachi. PATIENTS AND METHODS: Twenty-two patients with macular pucker underwent surgical repair. Pars plana posterior vitrectomy with epiretinal membrane peeling and internal limiting membrane peeling (maculorrhexis) was carried out. Postoperative follow-up was done for one year. Main outcome measure were visual acuity, causes and ocular complications. Data was analyzed using SPSS Version-10. Non-parametric sign test with chi-square statistic was used to compare the pre-operative and postoperative outcome. RESULTS: The macular pucker was successfully removed in 18 patients that revealed high statistical significance regarding improvement in visual acuity. Earlier, significant improvement (18 / 22 cases) was observed at three-month postoperative examination (p < 0.0001). Insignificant (9/22) postoperative complications were noted at six-month post-operative follow-up. Metamorphopsia was relieved in 18 patients. Ten patients developed cataract, 4 patients developed increased intra-ocular pressure (transient) and two patients developed retinal detachment. CONCLUSION: Pars plana posterior vitrectomy with epiretinal membrane peeling and internal limiting membrane peeling (maculorrhexis) can successfully remove macular pucker, improve vision and relieve metamorphopsia.

Epiretinal Membrane↗
PubMed1999

Metabolic acidosis-induced retinopathy in the neonatal rat.

PURPOSE: Carbon dioxide (CO2)-induced retinopathy (CDIR) in the neonatal rat, analogous to human retinopathy of prematurity (ROP), was previously described by our group. In this model, it is possible that CO2-associated acidosis provides a biochemical mechanism for CDIR. Therefore, the effect of pure metabolic acidosis on the developing retinal vasculature of the neonatal rat was investigated. METHODS: A preliminary study of arterial blood pH was performed to confirm acidosis in our model. In neonatal rats with preplaced left carotid artery catheters, acute blood gas samples were taken 1 to 24 hours after gavage with either NH4Cl 1 millimole/100 g body weight or saline. In the subsequent formal retinopathy study, 150 newborn Sprague-Dawley rats were raised in litters of 25 and randomly assigned to be gavaged twice daily with either NH4Cl 1 millimole/100 g body weight (n = 75) or saline (n = 75) from day 2 to day 7. After 5 days of recovery, rats were killed, and retinal vasculature was assessed using fluorescein perfusion and ADPase staining techniques. RESULTS: In the preliminary pH study, the minimum pH after NH4Cl gavage was 7.10+/-0.10 at 3 hours (versus 7.37+/-0.03 in controls, mean +/- SD, P < 0.01). In the formal retinopathy study, preretinal neovascularization occurred in 36% of acidotic rats versus 5% of controls (P < 0.001). Acidotic rats showed growth retardation (final weight 16.5+/-3.0 g versus 20.2+/-2.6 g, P < 0.001). The ratio of vascularized to total retinal area was smaller in acidotic rats (94%+/-4% versus 96%+/-2%, P < 0.001). CONCLUSIONS: Metabolic acidosis alone induces neovascularization similar to ROP in the neonatal rat. This suggests a possible biochemical mechanism by which high levels of CO2 induce neovascularization and supports the suggestion that acidosis may be an independent risk factor for ROP.

Acidosis↗
PubMed1999

Disruption of laminin beta2 chain production causes alterations in morphology and function in the CNS.

From the elegant studies of Ramon y Cajal (1909) to the current advances in molecular cloning (e.g., Farber and Danciger, 1997), the retina has served as an ideal model for the entire CNS. We have taken advantage of the well described anatomy, physiology, and molecular biology of the retina to begin to examine the role of the laminins, one component of the extracellular matrix, on the processes of neuronal differentiation and synapse formation in the CNS. We have examined the effect of the deletion of one laminin chain, the beta2 chain, on retinal development. The gross development of retinas from laminin beta2 chain-deficient animals appears normal, and photoreceptors are formed. However, these retinas exhibit several pathologies: laminin beta2 chain-deficient mice display abnormal outer segment elongation, abnormal electroretinograms, and abnormal rod photoreceptor synapses. Morphologically, the outer segments are reduced by 50% in length; the outer plexiform layer of mutant animals is disrupted specifically, because only 7% of observed rod invaginating synapses appear normal, whereas the inner plexiform layer is undisturbed; finally, the rate of apoptosis in the mutant photoreceptor layer is twice that of control mice. Physiologically, the electroretinogram is altered; the amplitude of the b-wave and the slope of the b-wave intensity-response function are both decreased, consistent with synaptic disruption in the outer retina. Together, these results emphasize the prominence of the extracellular matrix and, in particular, the laminins in the development and maintenance of synaptic function and morphogenesis in the CNS.

Animals↗
PubMedDate not supplied

[Identification of a de novo mutation in a patient without von Hippel-Lindau syndrome: clinical and diagnostic implications].

Von Hippel-Lindau (VHL) disease is characterized by a high predisposition to develop retinal angiomas, hemangioblastomas of the central nervous systems, renal cysts and renal carcinomas, pheochromocytomas, pancreatic cysts, and cystadenomas of the epididymis. The VHL gene was isolated in 1993; this fact allows to carry out presymptomatic diagnostic of this disease. We report on the case of patient with the suspicious++ and of hereditary VHL, although she had not familial history. By means of sequence the VHL gene was studied a mutation in exon 2 (GTT130CTT) that results in an amino acid change was found. This mutation could not be detected in her parents, pointing out that this is a de novo case. Patient has two sons, of 18 and 13 years old. The genetic analysis of the youngest showed that he was not a mutation carrier; while the eldest denied to be explored. The genetic study allows, in cases without familial history, to determine if they have the hereditary form of the disease and to study the siblings periodically until the beginning of the disease.

Adult↗
PubMed1999

[Congenital toxoplasmosis: presentation of a case].

We report a case of a 4 months old boy with esotropia of the left eye with large bilateral chorioretinal toxoplasmic macular scars. Chorioretinal scars are the most common eye finding in congenital toxoplasmosis and are often located in the macular region. Most infants with congenital infection are asymptomatic at birth but will develop retinal and/or neurologic damage later in life with consequent loss of vision. A routine examination of the fundus and computed tomography of the head can be negative. Serologic testing is essential for the diagnosis and the follow-up of the infection. Every infant with evident or suspected congenital infection by Toxoplasma gondii must be treated by Pyrimethamine, Sulphadiazine and Folinic Acid during at least the first year of life with regular serologic testing and ophthalmologic examination. Neurologic outcome is better with treatment and the risk of chorioretinitis seems reduced.

Child, Preschool↗
PubMed2000

The epithelial sodium channel (ENaC) in rodent retina, ontogeny and molecular identity.

PURPOSE: To assess the appearance of the epithelial sodium channels (ENaC) during retinal development and establish its molecular identity. METHODS: Photoreceptors were isolated by horizontal sectioning of rat retina with a vibratome series 1000. Intact retina and isolated photoreceptors were analyzed for the developmental appearance of ENaC using the Polymerase Chain Reaction (PCR) technique. Immunofluorescence was conducted with the aid of an antibody raised against the 14 amino acids peptide QGLGKGDKREEQGL, corresponding to the N-terminal region (44-58 aa) of alpha ENaC. RESULTS: ENaC message was present in rat retina photoreceptors, isolated just one day after birth. The bipolar and ganglion cell layers, separated from whole retina by vibratome, also contained the ENaC message. The partial sequence of the photoreceptor ENaC (496 base) exhibited one hundred percent homology with the channel from rat known sources. Immunochemistry revealed that only the outer nuclear layer was positive for the ENaC in one-day-old rat; the inner segment became immunopositive at the age of 9 days. CONCLUSION: The ENaC is present in the retina and visible soon after birth. These observations suggest that ENaC may prove to have physiological importance in the retina but until now its function is unknown.

Amino Acid Sequence↗
PubMed2000

Unusual association of Kikuchi's disease and dengue virus infection evolving into systemic lupus erythematosus.

Kikuchi's disease is a histologically alarming self-limiting condition typically affecting the lymph nodes of young females. A 13-year-old girl was presented with fever, skin rash and cervical lymphadenopathy. On examination she was found febrile, mild pallor was present and she had lymphadenopathy. Liver was palpable. Cervical lymph node biopsy showed histiocytic necrotising lymphadenitis (Kikuchi's disease). Dengue virus serology for IgG blot showed evidence of seroconversion in serial samples. She was treated with antibiotics and fluconazole and cyclosporin A. During hospitalisation she developed retinal vasculitis. She was reviewed after one month and showed rashes of subacute cutaneous lupus erythematosus. This case can be described to be a triggering event by dengue viral infection causing abnormal immune response leading initially to Kikuchi's disease and later on to systemic lupus erythematosus.

Adolescent↗
PubMedDate not supplied

Taurine: a conditionally essential amino acid in humans? An overview in health and disease.

Taurine, a sulphur containing amino acid, is the most abundant intracellular amino acid in humans, and is implicated in numerous biological and physiological functions. This comprehensive overview explores areas, from its characterisation to its potential clinical benefit as a conditionally essential amino acid and a pharmaconutrient. In healthy individuals the diet is the usual source of taurine; although in the presence of vitamin B6 it is also synthesised from methionine and cysteine. Taurine has a unique chemical structure that implies important physiological functions: bile acid conjugation and cholestasis prevention, antiarrhythmic/inotropic/chronotropic effects, central nervous system neuromodulation, retinal development and function, endocrine/metabolic effects and antioxidant/antiinflammatory properties. Taurine is an essential amino acid for preterm neonates and is assured by breast milk. Specific groups of individuals are at risk for taurine deficiency and may benefit from supplementation, e.g. patients requiring long-term parenteral nutrition (including premature and newborn infants); those with chronic hepatic, heart or renal failure. Further studies are required to determine the benefits of replenishing taurine pools as well as the need to include taurine routinely in parenteral nutrition regimens.

Amino Acids, Essential↗
PubMed2003

[Cervical medullary metastasis in a patient with Von Hippel-Lindau disease].

Von Hippel-Lindau disease is an autosomal dominant disorder mainly characterized by hemangioblastoma(s) associated with kidney clear-cell carcinoma. Hemangioblastoma represents 2 to 3% of all central nervous system tumors whereas extramedullary metastasis accounts for 30 to 50% of all intravertebral column tumors. The most common sites of metastatic dissemination in order of frequency are the lung, breast, prostate and kidney. We report a case of an unusual cervical intradural extramedullary metastasis of clear-cell kidney carcinoma associated with a cervical spinal cord hemangioblastoma in a 45-year-old patient with Von Hippel-Lindau disease who had developed retinal hemangioblastomas 20 years earlier. A review of the relevant literature is proposed.

Adult↗
PubMed2004

Minimal 16q genomic loss implicates cadherin-11 in retinoblastoma.

Retinoblastoma is initiated by loss of both RB1 alleles. Previous studies have shown that retinoblastoma tumors also show further genomic gains and losses. We now define a 2.62 Mbp minimal region of genomic loss of chromosome 16q22, which is likely to contain tumor suppressor gene(s), in 76 retinoblastoma tumors, using loss of heterozygosity (30 of 76 tumors) and quantitative multiplex PCR (71 of 76 tumors). The sequence-tagged site WI-5835 within intron 2 of the cadherin-11 (CDH11) gene showed the highest frequency of loss (54%, 22 of 41 samples tested). A second hotspot for loss (39%, 9 of 23 samples tested) was detected within intron 2 of the cadherin-13 (CDH13) gene. Furthermore, deletion of the exons of CDH11 and/or WI-5835 was shown by quantitative multiplex PCR in 17 of 30 (57%) of previously untested tumors. Immunoblot analyses revealed that 91% (20 of 22) retinoblastoma exhibited either a complete loss or a decrease of the intact form of CDH11 and 8 of 13 showed a prevalent band suggestive of the variant form. Copy number of WI-5835 for these samples correlated with CDH11 protein expression. CDH11 staining was evident in the inner nuclear layer in early mouse retinal development and in small transgenic murine SV40 large T antigen-induced retinoblastoma tumors, but advanced tumors frequently showed loss of CDH11 expression by reverse transcription-PCR, suggestive of a role for CDH11 in tumor progression or metastasis. CDH13 protein and mRNA were consistently expressed in all human and murine retinoblastoma compared with normal adult human retina. Our analyses implicate CDH11, but not CDH13, as a potential tumor suppressor gene in retinoblastoma.

Animals↗