The majestic canopy-emergent genus Dinizia (Leguminosae: Caesalpinioideae), including a new species endemic to the Brazilian state of Espírito Santo.

Since its description, almost 100 years ago, the genus Dinizia has been treated as monospecific, comprising the single canopy-emergent species Dinizia excelsa Ducke which grows in non-flooded Amazonian forests of Guyana, Suriname and seven states of northern and central-western Brazil. Dinizia jueirana-facao G. P. Lewis & G. S. Siqueira, which grows in a restricted area of semi-deciduous Atlantic rain forest in Espírito Santo state, Brazil, is described as a new species in the genus. The new species is also a canopy-emergent of impressive stature. We provide descriptions for both species, a key to species identification, a distribution map and the new species is illustrated. Fossil leaves, inflorescences and fruit provide evidence for a Dinizia-like ancestor occurring in south-eastern North America during the Eocene. In contrast to D. excelsa where pollen is dispersed in tetrads, the pollen of D. jueirana-facao is shed in monads. D. jueirana-facao is considered critically endangered following IUCN conservation criteria, whereas D. excelsa is assessed to be of least concern. A lectotype is designated for D. excelsa.

[Possible role of alkylphosphocholines in retinal reattachment surgery]. / Mögliche rolle von alkylphosphocholinen bei der ablatio-chirurgie.

BACKGROUND: Proliferative vitreoretinopathy (PVR) is a major complication after retinal detachment surgery, but there is no established pharmacotherapy available to control the cell biology of the disease. The aim of this study was to investigate the role of alkylphosphocholines [APCs; erucylphosphocholine (ErPC) was used in this study], novel pharmacologic substances with antiproliferative properties, on intraretinal proliferation initiated by experimental retinal detachment in a well-established in vivo model. METHODS: Retinal detachments were created in adult pigmented rabbits. ErPC was injected intravitreally on either day 1 or day 2 after detachment. Bromodeoxyuridine (5-bromo-2-deoxyuridine, BrdU) was injected on day 3. Following fixation, retinas were triple-labelled with anti-BrdU (proliferation marker), Isolectin B4 (retinal microglia marker), and anti-vimentin (retinal Mueller glia cell marker). The number of anti-BrdU-labelled cells per millimeter of retina was determined from sections imaged by laser scanning confocal microscopy. Toxicity was assessed by light and electron microscopy. RESULTS: A single intravitreal injection of ErPC had a significant effect on reducing the number of proliferating non-neural retinal cells on day 3 after experimental retinal detachment in the rabbit. Injection of ErPC on day 1 was more effective than when given on day 2. No evidence of toxicity was observed in the retina on day 3 for any of the conditions. CONCLUSIONS: APCs are novel pharmacologic substances that significantly inhibited intraretinal proliferation after experimental retinal detachment in this in vivo model. They could be considered as an adjunct therapy at the time of retinal reattachment surgery to potentially prevent proliferative vitreoretinal diseases such as PVR. However, long-term toxicity studies must be performed before APCs can be considered for clinical application.

Factors influencing blood supply in wound granuloma quantitated by a new in vivo technique.

A new quantitative assay for measuring angiogenesis in a s.c. located sponge implant in rats is described. Using this model, which detects neovascularization by measuring alterations in 133Xe clearance, it has been shown that the known angiogenic factors, transforming growth factor alpha and tumor necrosis factor alpha, cause maximum vascularization of the sponge to occur by Day 11 postimplantation compared with Days 15 to 17 in control animals. The monokine interleukin 1 alpha is shown to be strongly angiogenic, suggesting that more than one macrophage-derived cytokine may be the active mediator in macrophage-induced angiogenesis. Extracellular matrix proteins appear to play a role in regulating the angiogenic response such that presoaking sponges in laminin (40 micrograms/ml) or fibrinogen (500 micrograms/ml) solutions induced a significant reduction in the time taken to achieve maximum 133Xe clearance values; no such enhancement of neovascularization was observed when sponges were presoaked in type IV collagen (100 micrograms/ml) solution. The assay described here, which is reproducible, objective, and quantitative, should be of considerable use in elucidating the molecular basis of angiogenesis regulation.

Role of tumor necrosis factor in flavone acetic acid-induced tumor vasculature shutdown.

Flavone acetic acid (FAA), a novel investigational antitumor agent, has been shown to cause early vascular shutdown in several experimental murine tumors, and this phenomenon is believed to be crucial to FAA's antitumor effects. However, the basis of this FAA-induced tumor vascular shutdown is unknown. In this study a radioactive tracer-clearance technique has been used as an objective indication of tumor blood flow to show that i.p. administered FAA induces a progressive and sustained reduction in blood flow in a colon 26 tumor growing s.c. in syngeneic mice. As early as 1 h after administration, there was a significant increase in the t1/2 clearance value for intratumorally injected 133Xe, reaching a peak at 3 h (117.3 +/- 36.4 versus 7.8 +/- 0.85 min for controls). Significant inhibition of blood flow was still apparent 48 h after a single injection of drug. This FAA-induced vascular shutdown was virtually abolished in tumor-bearing mice pretreated with an antiserum against tumor necrosis factor, while no such effect was observed in controls pretreated with nonimmune serum (t1/2 of 10.8 +/- 1.2 versus 65.6 +/- 8.0 min for controls). Furthermore, in vitro FAA was seen to induce tumor necrosis factor secretion from murine peritoneal cells and splenocytes. These studies suggest that FAA-induced tumor vascular shutdown in the colon 26 tumor is mediated by tumor necrosis factor.

Pharmacokinetics of ampicillin in cirrhosis.

Ampicillin pharmacokinetics was studied in 9 cirrhotic patients and in 8 healthy subjects to assess liver disease-related differences in distribution, elimination, and bioavailability of ampicillin. Plasma, urine, and ascites fluid samples were analyzed microbiologically. After intravenous doses, the cirrhotic patients have lower initial plasma concentrations of ampicillin because of the larger volume of distribution. Such patients usually have diminished renal function, which, because renal tubular secretion is the main route of excretion of ampicillin, causes prolonged retention of ampicillin. Metabolic-biliary clearance of ampicillin, normally accounting for removal of only 10% of the dose in normal subjects, is three times as great in cirrhotic patients. Peak ascites fluid concentrations of ampicillin ranged from 2 to 7 mcg/ml after 600 mg iv doses, and very slow clearance of ampicillin from the peritoneal cavity results in persistence in this compartment. Though absorption of ampicillin from capsules was often erratic, its bioavailability was similar in normal and cirrhotic subjects. These findings suggest that the usual course of ampicillin therapy of infections should not be altered in cirrhotic patients. On the other hand, reduction in dosage may be called for when there is renal impairment.

Diurnal blood pressure in patients with mild-to-moderate hypertension treated with once-daily benazepril hydrochloride.

This study evaluated the blood pressure effects of administration of once daily oral benazepril hydrochloride, a new angiotensin-converting enzyme (ACE) inhibitor, for mild-to-moderate hypertension. After a 2 to 4 week placebo baseline period, patients with diastolic blood pressure between 95 and 114 mm Hg, were randomized to receive either placebo or benazepril hydrochloride, 5, 10, 20, or 40 mg, once daily in double-blind fashion for 28 days. Blood pressure was measured predose and at 1, 2, 3, 4, 6, 8, 12, 16, 20, and 24 hours after the dose during inpatient observation days at the end of the placebo baseline period, and on the first and last day of the double-blind treatment period; and 24 hours after the dose at weekly outpatient visits. All doses of benazepril hydrochloride resulted in clinically important reductions in diastolic and systolic blood pressures that lasted between 12 and 24 hours after both the first dose, and following the last dose after 4 weeks of treatment. The findings indicate that benazepril hydrochloride may be clinically useful as once-daily monotherapy in many patients with hypertension.

Induction of cyclo-oxygenase by interleukin-1 in rheumatoid synovial cells.

The ability of interleukin-1 (IL-1) to stimulate prostaglandin E2 (PGE2) production by human rheumatoid adherent synovial cells was found to be time-dependent and sensitive to protein synthesis inhibitors. Cells incubated with exogenous arachidonic acid (10 microM) showed no increase in PGE2 production. However, with IL-1 (2.5 U/ml) and exogenous arachidonic acid there was a marked increase, with levels reaching twice that for cells incubated with IL-1 alone. Aspirin pre-treatment studies and the use of [acetyl-14C]aspirin showed that IL-1 increased PGE2 production through the induction of cyclo-oxygenase.

Distribution of S- and M-cones in normal and experimentally detached cat retina.

The lectin peanut agglutinin (PNA) and antibodies to short (S)- and medium to long wavelength (M/L)-sensitive cones were utilized in order to define the relative distributions of the two spectral types of cone across the domestic cat's retina. These values, in turn, were compared to those from retinas that had been experimentally detached from the retinal pigment epithelium. The pattern of cone distribution in the normal cat's retina is established by the preponderance of M-cones that constitute between 80% and 90% of all cones. Their peak density of over 26,000 cells/mm(2) resides at the area centralis. Though M-cone density decreases smoothly to the ora serrata where they have densities as low as 2,200 cells/mm(2), the density decrease along the nasotemporal axis is slower,creating a horizontal region of higher cone density. S-cones constitute between 10% and 20% of all cones, the number being quite variable even between individual animals of similar age. The highest S-cone densities are found in three distinct locations: at the superior far periphery near the ora serrata, immediately at the area centralis itself, and in a broad zone comprising the central and lower half of the inferior hemiretina. S-cones in the cat retina do not form a regular geometrical array at any eccentricity. As for the detached cat retina, the density of labeled S-cone outer segments (OS) decreases rapidly as early as 1 day postdetachment and continues decreasing to day 28 when the density of cones labeling with anti-S opsin has dropped to less than 10% of normal. This response points to a profound difference between rods and cones; essentially all rods, including those without OS, continue to express their opsin even in long-term detachments. The implications of these results for visual recovery after retinal reattachment are discussed.

Müller cell outgrowth after retinal detachment: association with cone photoreceptors.

PURPOSE: Subretinal gliosis is a relatively common occurrence after retinal reattachment. Because Müller cell processes only intermittently penetrate the outer limiting membrane (OLM) beneath extensive detachments, this study was conducted to determine whether this was preferentially associated with rod or cone photoreceptors. METHODS: Cat retinas were detached from the retinal pigment epithelium and 3 days later were fixed in 4% paraformaldehyde, embedded in 5% agarose, sectioned at 100 microm, and processed for standard immuohistochemistry. The retinas were double labeled with either anti-vimentin and anti-long/medium wavelength-sensitive (anti-L/M) cone opsin or anti-glial fibrillary acidic protein (GFAP) and biotinylated peanut agglutinin (PNA). RESULT: The hypertrophy of Muller cells was readily traced using antibodies to vimentin and GFAP. When labeling with these antibodies was combined with labeling by either antibodies to cone opsins or biotinylated PNA, a consistent relationship was observed between the Müller cell processes growing through the OLM and cone photoreceptors. CONCLUSIONS. The growth of Müller cell processes into the subretinal space forms a fibrotic layer that completely inhibits the regeneration of outer segments. The current results show that there appears to be a highly specific interaction between growing Müller cell processes and cone photoreceptors during the earliest phase in this process.

Changes in the organization and expression of cytoskeletal proteins during retinal degeneration induced by retinal detachment.

PURPOSE: The goal of this study was to determine the changes in the organization of the retinal cytoskeleton after experimental retinal detachment. METHODS: Cat retinas were detached from the retinal pigment epithelium and then processed for Western blot analysis and fluorescence microscopy. Proteins examined included glial fibrillary acidic protein (GFAP), vimentin, tubulin, and actin. Sections were viewed using a laser scanning confocal microscope. RESULTS: GFAP and vimentin: At 1 day after detachment, there was an aggregation of intermediate filaments in the endfoot of Müller cells. At 3 days, intermediate filament containing Müller cell processes could be detected within the subretinal space, and, at 28 days, these processes formed large glial scars in the subretinal space. beta-tubulin: At 3 days after detachment, an increase in immunolabeling could be detected within the Müller cell endfoot and in Müller cell processes within the subretinal space. Actin: At 3 days after detachment, rhodamine-phalloidin staining decreased in the inner segments, the photoreceptor synaptic terminals, and the outer limiting membrane. CONCLUSIONS: The decrease in labeling of the photoreceptor inner segment and synaptic terminal cytoskeleton may be a key indicator of early changes in photoreceptors after detachment. The increase in cytoskeletal proteins GFAP, vimentin, and tubulin within the retinal Müller cells after detachment may help to stabilize this cell type as it hypertrophies during glial scar formation. Inhibition of this response may aid in the treatment of diseases in which Müller cell hypertrophy plays a role.

FGFR1, signaling, and AP-1 expression after retinal detachment: reactive Müller and RPE cells.

PURPOSE: To identify changes in cellular signaling pathways and AP-1 expression in retina and retinal pigmented epithelium (RPE) after experimental retinal detachment (RD). METHODS: Cat and rabbit neural retinas were separated from the RPE in vivo for 5 minutes to 28 days. Tissues were removed and processed for Western blotting, immunohistochemistry, in situ hybridization, and immunoprecipitation experiments. RESULTS: An ordered sequence of events occurs after RD: (1) fibroblast growth factor (FGF) receptor 1 (FGFR1, flg) is phosphorylated in the retina within 15 minutes and dephosphorylated 2 hours after RD; (2) The extracellular signal-regulated kinase (ERK) is phosphorylated in both Müller and RPE cells within 15 minutes and remains so for several days; (3) De novo expression of c-fos mRNA coincides with increased c-Fos and c-Jun immunoreactivity in both Müller and RPE cells; (4) CREB is phosphorylated in a subpopulation of photoreceptors; and (5) STAT3 and NF-kappaB are activated in inner nuclear layer cells by 1 day of RD. CONCLUSIONS: These data suggest that nonneuronal cells (RPE and Müller cells) respond to RD very rapidly by stimulating ERK signaling and AP-1 transcription factor expression. Furthermore, these data suggest that basic fibroblast growth factor (FGF-2, bFGF) is involved in initiating the retina's earliest responses to RD. The events described here precede changes in gene expression and morphology that can have serious effects on visual outcome in humans treated for retinal detachment or other retinal injuries.

The ability of hyperoxia to limit the effects of experimental detachment in cone-dominated retina.

PURPOSE: To determine the ability of oxygen supplementation to ameliorate the effects of retinal detachment in a cone-dominated retina. METHODS: Retinal detachments were created in the right eyes of ground squirrels and the animals immediately placed in normoxic (room air) or hyperoxic (70% oxygen) conditions for 3 days. The retinas were sampled from different regions and investigated morphologically or immunocytochemically by light or confocal microscopy. Agarose embedded sections were immunostained with antibody probes to cytochrome oxidase, synaptophysin, medium-to-long wavelength-sensitive (M/L) cone opsin, rod opsin, excitatory amino acid transporter 1 (EAAT1), glutamate synthetase (GS), cellular retinaldehyde-binding protein (CRALBP), and peanut agglutinin (PNA) lectin. Retinal wholemounts were labeled with PNA and antibodies to short (S)-wavelength-sensitive cone opsin and rod opsin. Cell death was examined using a TUNEL assay on agarose sections or using toluidine blue staining on semithin sections. RESULTS: The percentage of dying cells relative to the total nuclei in the photoreceptor layer was significantly reduced, and the total number of nuclei was greater in hyperoxic animals. Triple labeling using TUNEL, anti-M/L cone opsin and anti-rod opsin showed that hyperoxia had a remarkable effect both on the reduction of cone cell death and the maintenance of the overall structure of cone photoreceptors. Analysis of the retinal wholemounts demonstrated the preservation of PNA, S-cone, and rod opsin antibody labeling in the detachments maintained in hyperoxic conditions. Although the disruption of cytochrome oxidase and synaptophysin was seen in normoxic animals, there was minimal disruption in hyperoxic animals. Labeling with anti-EAAT1, anti-GS, and anti-CRALBP was increased in the Müller cells of normoxic animals with detachments, but was decreased in the hyperoxic animals. CONCLUSIONS: Hyperoxia prevents the degeneration of both rods and cones in retinas heavily dominated by cones and mitigates the effect of detachment on Müller cell reactivity. The current results suggest that the rescue of cones is not secondary to that of rods.

Apoptotic photoreceptor degeneration in experimental retinal detachment.

PURPOSE: To investigate the possibility that cell death in retinal detachment may occur by reactivation of apoptotic programmed cell death mechanisms. METHODS: Unilateral retinal detachments were created in adult cats using 0.25% sodium hyaluronate; detached and control retinas were studied at different intervals. Internucleosomal DNA fragmentation (one of the landmarks of apoptosis) was investigated in tissue sections with the TUNEL technique, which uses terminal transferase to label with biotinylated nucleotides the 3' ends of DNA fragments. Sections also were labeled with propidium iodide, which intensely stains pyknotic nuclei. In addition, one time point was selected for analysis with electron microscopy. RESULTS: TUNEL-positive (T+) and propidium iodide-positive (PI+) cells almost never were observed in retinas from control eyes, but they were abundant at defined time points after retinal detachment, appearing almost exclusively in the photoreceptor layer. Their frequency was particularly high 1 to 3 days after detachment but declined rapidly over the next several weeks. T+ cells were still present 28 days after retinal detachment. Electron microscopy also revealed evidence of apoptotic cells after retinal detachment. CONCLUSIONS: Results are consistent with the hypothesis that photoreceptor degeneration after retinal detachment occurs through apoptosis, usually associated with intrinsic, programmed cell death mechanisms. The detection of a rapid wave of photoreceptor degeneration seems to suggest that early therapeutic interventions might be recommended; agents capable of interfering with the apoptotic mechanism could have a role in the prevention of cell losses that represent a critical complication of retinal detachment.

Neurite outgrowth from bipolar and horizontal cells after experimental retinal detachment.

PURPOSE: To study the responses of horizontal cells and rod bipolar cells, the second-order neurons in the retina, to the degeneration induced by experimental retinal detachment. METHODS: Retinas from the eyes of domestic cats were examined 1, 3, 7, and 28 days after detachment using immunocytochemical and electron microscopic analyses. Retinal sections were labeled with antibodies to synaptophysin, calbindin D, and protein kinase C (PKC), proteins that serve as markers for synaptic terminals, horizontal cells, and rod bipolar cells, respectively. RESULTS: Beginning 1 day after detachment, the outer plexiform layer becomes disorganized and synaptophysin-labeled photoreceptor terminals are detected among the cell bodies of photoreceptors in the outer nuclear layer (ONL). At the same time, horizontal and rod bipolar cell processes grow into the ONL. In some cases, these processes contact photoreceptor terminals that have withdrawn deep into the ONL. Double-labeling experiments with antibodies to glial fibrillary acidic protein (Müller cell labeling) and phosphodiesterase gamma (cone labeling) demonstrate that the calbindin D- and PKC-positive neurite outgrowths are not derived from either Müller cells or cone photoreceptors. CONCLUSIONS: Horizontal and rod bipolar cell processes lengthen after retinal detachment, perhaps in response to a withdrawal of their presynaptic targets, the photoreceptor synaptic terminals. This apparent attempt to maintain synaptic contact after injury demonstrates a plasticity in the adult retina that may be of importance for the recovery of vision in human patients.

Fluoropyrimidine treatment of ocular cicatricial disease.

The authors have studied the antiproliferative and anticontractile effects of fluorouracil, fluorouridine, and fluorodeoxyuridine on rabbit dermal fibroblasts. All three drugs have antiproliferative effects, the order of their efficacy being fluorodeoxyuridine greater than fluorouridine greater than fluorouracil. In contrast, only fluorouridine and fluorouracil have anticontractile effects. Fluorouridine requires less time of exposure and has greater anticontractile effects than fluorouracil. Thymidine eliminates the antiproliferative effects of fluorodeoxyuridine, but has no effect on either the antiproliferative or anticontractile effects of fluorouracil and fluorouridine. These results suggest that the anticontractile effects of the fluoropyrimidines are caused by their incorporation into RNA and not by the inhibition of DNA synthesis. Metabolites of fluorouracil may provide enhanced control of cell proliferation and contractility in the management of ocular disorders such as proliferative vitreoretinopathy and glaucoma.

Antiproliferative and anticontractile effects of liposome encapsulated fluoroorotate.

Incorporation of fluoroorotate into liposomes increases its growth inhibitory potency for rabbit dermal fibroblasts 30-fold. The optimal lipid composition of the liposomes is dipalmitoylphosphatidylglycerol:cholesterol (67:33). Liposomes prepared by reverse phase evaporation without extrusion are the optimal liposomes for delivery. Fluoroorotate, like other RNA directed fluoropyrimidines, inhibits the contractility of rabbit dermal fibroblasts. The effect is greatest when the cells are exposed to the drug for the 48-72 hr immediately prior to measurement of cell contractility. Encapsulation of fluoroorotate increases its anticontractile potency 10-fold. The anticontractile effects of both free and encapsulated fluoroorotate on the cells last at least 12 days. Leakage studies suggest that the loss of drug from the liposomes under storage conditions will be quite low. Leakage studies also confirm that serum will accelerate the loss of drug from the liposomes and that sonicated liposomes leak much more rapidly than larger liposomes. However, the large difference between egg phosphatidylglycerol and dipalmitoylphosphatidylglycerol liposomes for drug delivery is not explained by leakage studies. These results suggest that encapsulated fluoroorotate may be a useful adjunct to surgery for treatment of proliferative vitreoretinopathy.

Intraretinal proliferation induced by retinal detachment.

Cellular proliferation after retinal detachment was studied by 3H-thymidine light microscopic autoradiography in cats that had experimental detachments of 0.5-180 days duration. The animals underwent labeling 2 hr before death with an intraocular injection of 200 microCi of 3H-thymidine. The number of labeled nuclei were counted in 1-micron thick tissue sections in regions of detachment, in regions of the experimental eyes that remained attached, and in control eyes that had no detachments. In the normal eye, in one that had only the lens and vitreous removed, and in the eyes with 0.5- and 1-day detachments, the number of labeled nuclei ranged from 0/mm (0.5-day detachment) to 0.38/mm (lens and vitreous removed only). By 2 days postdetachment, the number of labeled nuclei increased to 2.09/mm. The highest levels of labeling occurred in two animals with detachments of 3 (7.86/mm) and 4 (7.09/mm) days. Thereafter, the numbers declined steadily until near-baseline counts were obtained at 14 days. The number of labeled nuclei was slightly elevated in the attached regions of two animals with 3-day detachments. Labeled cell types included: Müller cells, astrocytes, pericytes, and endothelial cells of the retinal vasculature, and both resident (microglial cells) and invading macrophages. In an earlier study RPE cells were also shown to proliferate in response to detachment. Thus, these data show that proliferation is a rapid response to detachment, reaching a maximum within 4 days, and that virtually every nonneuronal cell type in the retina can participate in this response. The data suggest that events leading to such clinical manifestations as proliferative vitreoretinopathy and subretinal fibrosis may have their beginnings in this very early proliferative response.

Use of the MIB-1 antibody for detecting proliferating cells in the retina.

PURPOSE: To study intraretinal proliferation as a response to experimental retinal detachment using an antibody that recognizes the nuclear specific antigen Ki-67 in proliferating cells. METHODS: Experimental retinal detachments were produced in cats (1, 3, 7, and 28 days) and rabbits (1, 3, and 7 days). The animals were killed and the eyes were fixed and embedded in paraffin. Histologic sections were processed for immunohistochemistry using the MIB-1 antibody to detect the Ki-67 protein. Labeled cells were identified, and the proliferative response was quantified. RESULTS: In normal cat retina, approximately 0.05 cells per millimeter of retina are labeled. In cat retina detached for 1, 3, 7, or 28 days, the number of cells labeled by MIB-1 is 0.06, 5.03, 1.38, and 0.23 cells per millimeter of retina, respectively. MIB-1 labeling yields an approximate fivefold increase over the number of proliferating cells detected in retinal sections using 3H-thymidine autoradiography. Detachment of the rabbit retina elicits a similar response as measured by MIB-1 immunohistochemistry. CONCLUSIONS: In contrast to 3H-thymidine, which labels cells in S-phase only, the MIB-1 antibody labels proliferating cells regardless of their location within the cell cycle. MIB-1 labeling, therefore, is a more accurate means of evaluating cellular proliferation in the retina and elsewhere in the central nervous system, and it is a relatively simple way of evaluating the effects of agents that may affect this response.

Amino acid signatures in the detached cat retina.

PURPOSE: Expressions of certain macromolecules are altered by experimental retinal detachment in the cat. Related alterations in micromolecular signatures of neurons, Müller cells, and the retinal pigment epithelium (RPE) were investigated. METHODS: High-performance immunochemical mapping, image registration, and quantitative pattern recognition were combined to analyze the amino acid contents of virtually all retinal cell types after 3 to 84 days of detachment. RESULTS: Retinal micromolecular signatures showed a spectrum of alterations. The glutamate contents of Müller cells increased and remained elevated for weeks after detachment. Multispectral signatures of Müller cells showed massive metabolic instability in early detachment stages that ultimately resolved as a homogeneous profile significantly depleted in glutamine. Retinal pigment epithelial cell signals also changed dramatically, displaying an initial glutamate spike and then a prolonged decline, even as taurine levels followed an opposite pattern of initial loss and slow restoration. Neurotransmitter signatures of surviving neurons showed extensive precursor-level variation, and, in one case, GABAergic horizontal cells displayed anomalous sprouting. CONCLUSIONS: Dramatic changes in Müller cell amino acid signatures triggered by retinal detachment are partially consistent with losses in glutamine synthetase activity. Taurine signal variations suggest that orthotopic RPE cells attempt to regulate abnormal taurine concentrations in the enlarged subretinal space. Surviving neurons possess characteristic neurotransmitter signals, but their metabolite regulation seems abnormal. On balance, microchemical and structural anomalies develop in the detached cat retina that represent serious barriers to recovery of normal visual function.

Effects of the neurotrophin brain-derived neurotrophic factor in an experimental model of retinal detachment.

PURPOSE: To examine the effects of brain-derived neurotrophic factor (BDNF) in an animal model of retinal detachment. METHODS: Cat retinas were detached from the retinal pigment epithelium for either 7 or 28 days. Animals received either an intravitreal injection of BDNF (100 ILg) or phosphate-buffered saline (PBS), the vehicle for BDNF. Retinas were evaluated using morphology and immunocytochemistry. The width of the outer segment zone was measured, and the retinas were evaluated for changes in protein expression by labeling with antibodies to rod opsin, phosducin, synaptophysin, calbindin D, and glial fibrillary acidic protein (GFAP). The effect of BDNF on both proliferation and apoptotic cell death was examined. RESULTS: Although there was variability in the treated retinas, most of the animals receiving BDNF had well-organized outer segments that were longer than those in vehicle-treated controls. Immunocytochemistry revealed that treated retinas had consistently less opsin redistribution to the plasma membrane, less phosducin upregulation, and fewer calbindin D-labeled horizontal cell processes. BDNF did not reduce overall cell death in the detachments or death of photoreceptors by apoptosis. However, it significantly reduced the proliferative response of Miller cells and the extent of upregulation of GFAP. CONCLUSIONS. The results suggest that BDNF may aid in the recovery of the retina after reattachment by maintaining the surviving photoreceptor cells, by reducing the gliotic effects in Müller cells, and perhaps by promoting outer segment regeneration.