Age influences the thermal suitability of Plasmodium falciparum transmission in the Asian malaria vector Anopheles stephensi.

Models predicting disease transmission are vital tools for long-term planning of malaria reduction efforts, particularly for mitigating impacts of climate change. We compared temperature-dependent malaria transmission models when mosquito life-history traits were estimated from a truncated portion of the lifespan (a common practice) versus traits measured across the full lifespan. We conducted an experiment on adult female Anopheles stephensi, the Asian urban malaria mosquito, to generate daily per capita values for mortality, egg production and biting rate at six constant temperatures. Both temperature and age significantly affected trait values. Further, we found quantitative and qualitative differences between temperature-trait relationships estimated from truncated data versus observed lifetime values. Incorporating these temperature-trait relationships into an expression governing the thermal suitability of transmission, relative R0(T), resulted in minor differences in the breadth of suitable temperatures for Plasmodium falciparum transmission between the two models constructed from only An. stephensi trait data. However, we found a substantial increase in thermal niche breadth compared with a previously published model consisting of trait data from multiple Anopheles mosquito species. Overall, this work highlights the importance of considering how mosquito trait values vary with mosquito age and mosquito species when generating temperature-based suitability predictions of transmission.

REFERENCE AND BASELINE HEMATOCRIT MEASURES FOR THE THREATENED NEW ENGLAND COTTONTAIL (SYLVILAGUS TRANSITIONALIS) AND COMPARISON WITH SYMPATRIC EASTERN COTTONTAIL (SYLVILAGUS FLORIDANUS) RABBITS.

From June 2014 to June 2015, capillary tube collections of blood were obtained concurrently with ear clips of trapped free-ranging, globally vulnerable New England cottontails (NEC; Sylvilagus transitionalis) and eastern cottontail rabbits (EC; Sylvilagus floridanus) in the Hudson Valley region of New York, United States. Species identification (NEC, EC) and sex (NEC) were determined genetically using a mitochondrial DNA assay and Y chromosome marker, respectively. Hematocrit values were obtained using a microhematocrit centrifuge. We provide the reference values 35.15-49.55 (2.5 and 97.5 percentiles) and 90% confidence intervals (CI) [lower: 33.00, 36.08; upper: 46.95, 51.00], for hematocrit of NEC. The mean hematocrit for NEC was 42.35% (SE = 0.58, n = 47) and a comparative contemporaneous mean in the same area for EC [39.96 (SE = 0.81, n = 26)], which was significantly different from NEC (P = 0.02). There was a significant sex difference for NEC [male: 43.99 (SE = 1.02, n = 28); female: 39.92 (SE = 0.78, n = 19), P < 0.0001], though not for EC.

Postnatal development of electrophysiological properties of principal neurons in the rat basolateral amygdala.

The basolateral amygdala (BLA) is critically involved in the pathophysiology of psychiatric disorders, which often emerge during brain development. Several studies have characterized postnatal changes to the morphology and biochemistry of BLA neurons, and many more have identified sensitive periods of emotional maturation. However, it is impossible to determine how BLA development contributes to emotional development or the aetiology of psychiatric disorders because no study has characterized the physiological maturation of BLA neurons. We addressed this critical knowledge gap for the first time using whole-cell patch clamp recording in rat BLA principal neurons to measure electrophysiological properties at postnatal day (P)7, P10, P14, P21, P28 and after P35. We show that intrinsic properties of these neurons undergo significant transitions before P21 and reach maturity around P28. Specifically, we observed significant reductions in input resistance and membrane time constant of nearly 10-and 4-fold, respectively, from P7 to P28. The frequency selectivity of these neurons to input also changed significantly, with peak resonance frequency increasing from 1.0 Hz at P7 to 5.7 Hz at P28. In the same period, maximal firing frequency significantly increased and doublets and triplets of action potentials emerged. Concomitantly, individual action potentials became significantly faster, firing threshold hyperpolarized 6.7 mV, the medium AHP became faster and shallower, and a fast AHP emerged. These results demonstrate neurons of the BLA undergo vast change throughout postnatal development, and studies of emotional development and treatments for juvenile psychiatric disorders should consider the dynamic physiology of the immature BLA.

Defining herbivore assemblages in the Kruger National Park: a correlative coherence approach.

Spatial associations of seven herbivore species in the Kruger National Park, South Africa, are analyzed using a new technique, Correlative Coherence Analysis (CoCA). CoCA is a generalization of the concept of correlation to more than two sequences of numbers. Prior information on the feeding ecology and metabolic requirements of these species is used to contrast spatial scales at which hypothesized guild aggregation or competition occurs. These hypotheses are tested using 13 years of aerial census data collected during the dry season. Our results are consistent with the hypothesis that distributions of large and small species of the same feeding type (i.e., grazers and browsers) overlap in potentially resource-rich areas, but have lower similarity values across all areas because the higher tolerance of large species for low quality foods results in a more even spatial distribution of large species compared to small species.

Novel growth factors involved in the pathogenesis of proliferative vitreoretinopathy.

AIMS: To determine whether hepatocyte growth factor (HGF) and connective tissue growth factor (CTGF) are expressed in human specimens of proliferative vitreoretinopathy (PVR) and to propose a model of PVR pathogenesis based upon the known activities of these growth factors. Methods Immunohistochemical methods (ABC Elite) were used to demonstrate the presence of HGF and CTGF in cryostat sections of five human PVR membranes. RESULTS: In each of the five PVR membranes, stromal cells were immunohistochemically positive for both HGF and CTGF. Based upon this information and the known actions of these growth factors, a model of PVR pathogenesis was developed. In this model, injury of the retina induces an inflammatory response that upregulates HGF expression inducing the formation of multilayered groups of migratory retinal pigment epithelial cells (RPE). These RPE, present in a provisional extracellular matrix, come in contact with vitreous containing TGF-beta. The TGF-beta is activated, upregulating expression of CTGF. Under the influence of TGF-beta and CTGF, RPE become myofibroblastic and fibrosis ensues. Retinal traction induces further detachment continuing the cycle of retinal injury. CONCLUSIONS: HGF and CTGF are expressed in PVR membranes and may play important roles in the pathogenesis of PVR. The expression and function of these growth factors should be critically examined in human PVR specimens, in in vitro cultures of RPE, and in animal models of PVR.

Non-invasive Wedensky modulation within the QRS complex.

To investigate non-invasively induced Wedensky modulation, 2ms pulses of 5, 20 and 40mA were delivered between precordial and subscapular patches synchronously with the ORS complex. Wavelet vector magnitude was obtained for averaged modulated and non-modulated complexes. The surface area of a 3D-envelope of their difference (WSR) was compared in 59 patients with an uncomplicated follow-up after myocardial infarction (MI) (42 men, 64.3+/-9.1 years), in 30 patients with ischaemic heart disease and a history of ventricular tachycardia/fibrillation (VT/VF) (29 men, 63.1+/-9.8 years), and in 53 healthy subjects (control) (22 men, 56.6+/-10.1 years). Reproducibility of the assessment was tested by computing relative errors in a sub-population of 30 VT/VF patients and 47 controls. Wedensky modulation parameters differed significantly between control, MI and VT/VF subjects. In 10 ms post-modulation windows, the following WSR values were obtained: controls: 1184+/-496 (5mA), 1553+/-838 (20 mA) and 2092+/-1488 (40 mA); VT/VF: 861+/-412 (5mA), 1134+/-636 (20 mA) and 1320+/-1036 (40 mA); MI: 1305+/-885 (5mA) and 1779+/-1169 (20 mA). With all modulating energies used, the VT/VF patients differed significantly from both the controls and MI patients; control patients against VT/VF patients: p<0.004 (5 mA), p<0.01 (20 mA) and p<0.001 (40 mA); VT/VF patients against MI patients: p<0.02 (5mA), p<0.01 (20 mA); control patients against MI patients: all p=NS. The reproducibility assessment showed an acceptable stability of Wedensky modulation parameters. This study demonstrated that wavelet decomposition detects non-invasive Wedensky modulation within the QRS complex, and VT/VF patients are less sensitive to Wedensky modulation than control and MI patients.

Interferon beta affects retinal pigment epithelial cell proliferation via protein kinase C pathways.

BACKGROUND: The aim of this study is to see the effect of interferon beta (IFN-beta) on cell proliferation and the protein kinase C (PKC) signaling pathway. METHODS: Proliferation of cultured human retinal pigment epithelium (RPE) cells, with various concentrations of IFN-beta, and with or without 3% fetal calf serum (FCS), was assessed by cell counting. Effects of short (3 h) or prolonged (48 h) exposure of RPE cells to natural human IFN-beta were assessed by (3)H-thymidine uptake. Cytosolic and membranous PKC activity over time in cells treated with IFN-beta and calphostin C was also measured. RESULTS: IFN-beta inhibited the increased proliferation by FCS in the prolonged-exposure assay. The PKC inhibitor calphostin C also showed an inhibitory effect on RPE cell growth and (3)H-thymidine uptake in the chronic exposure with FCS. Short treatment with IFN-beta had no inhibitory or stimulatory effect on (3)H-thymidine uptake. Cytosolic and membranous PKC activity was strongly upregulated after short IFN-beta exposure but returned to original levels after 1 h. PKC activity was downregulated both in the cytosol and membrane after 24 or 48 h. CONCLUSION: IFN-beta inhibited RPE proliferation in vitro and the effect is mediated by upregulation of the PKC pathway.

Systemically expressed soluble Tie2 inhibits intraocular neovascularization.

Retinal and choroidal neovascularization are the most frequent causes of severe and progressive vision loss. Studies have demonstrated that Tie2, an endothelial-specific receptor tyrosine kinase, plays a key role in angiogenesis. In this study, we determined whether adenovirus-mediated gene delivery of extracellular domain of the Tie2 receptor (ExTek) could inhibit experimental retinal and choroidal neovascularization. Immunofluorescence histochemistry with a monoclonal antibody to human Tie2 showed that Tie2 expression is prominent around and within the base of newly formed blood vessels of retinal and choroidal neovascular lesions. A single intramuscular injection of adenovirus expressing ExTek genes achieved plasma levels of ExTek exceeding 500 microg/ml in mice for 10 days (in neonates) and 7 days (in adults). This treatment inhibited retinal neovascularization by 47% (p < 0.05) in a murine model of ischemia-induced retinopathy. The same treatment reduced the incidence and extent of sodium fluorescein leakage from choroidal neovascular lesions by 52% (p < 0.05) and 36% (p < 0.01), respectively, in a laser-induced murine choroidal neovascularization model. The same mice showed a 45% (p < 0.001) reduction of integrated area of the choroidal neovascularization. These findings indicate that Tie2 signaling is a common component of the angiogenic pathway in both retinal and choroidal neovascularization, providing a potentially useful target in the treatment of intraocular neovascular diseases.

Angiopoietin-1 upregulation by vascular endothelial growth factor in human retinal pigment epithelial cells.

PURPOSE: To determine whether vascular endothelial growth factor (VEGF) regulates angiopoietin (Ang)-1 and -2 expression in retinal pigment epithelial (RPE) cells. METHODS: Expression of VEGF, Ang1, and Ang2 in surgically removed human choroidal neovascular membranes (CNVMs) was analyzed by double-label confocal immunofluorescence microscopy. Total RNA was extracted from cultured human RPE cells treated with VEGF for mRNA analysis. Northern blot analysis was performed to examine the time course and dose response of Ang1 and Ang2 mRNA expression. mRNA stability and nuclear run-on analyses were performed. Secreted Ang1 and Ang2 protein levels in conditioned media from RPE cells were examined by Western blot analysis. RESULTS: Ang1 and Ang2 immunostaining colocalized with VEGF-positive stromal cells in human CNVMS: Ang1 and Ang2 mRNAs were expressed by cultured serum-starved RPE cells. VEGF upregulated Ang1 mRNA in a time- and dose-dependent manner without a significant change in Ang2 mRNA. Ang1 and Ang2 mRNAs in RPE cells were as stable as that of S18. VEGF stimulation further increased the half-life of Ang1 mRNA, but did not alter its transcription rate. VEGF increased the amount of Ang1, but not Ang2, protein secreted into the medium. CONCLUSIONS: The colocalization of Ang1 and Ang2 with VEGF in CNVM stromal cells and the upregulation of Ang1 expression by VEGF in cultured RPE cells suggest that VEGF may selectively modulate Ang expression during CNV.

T-wave morphology differences between patients with and without arrhythmic complication of ischemic heart disease.

The study investigated the differences in T-wave morphology between normal controls, patients with an uncomplicated follow-up after a myocardial infarction (MI), and patients with ischaemic heart disease and a history of ventricular tachycardia/fibrillation (VT/VF). The study population consisted of 164 healthy patients (age 53.4 +/- 18.7 years old, 80 women), 123 VT/VF patients (age 63.8 +/- 10.1 years old, 15 women), and 196 MI patients (age 59.2 +/- 10.0 years old, 23 women). In all patients, supine resting signal-averaged orthogonal electrocardiograms were obtained. After singular value decomposition of electrocardiogram signal, 2 T-wave morphology descriptors were calculated: total cosine R to T describing the global angle between repolarisation and depolarisation loops, and percentage of loop area expressing the irregularity of the T-wave loop (a more irregular wave results in a lower percentage of loop area value). Both parameters were practically uncorrelated (Controls: r = - .106, MI r = .161, and VT/VF r = .173) and different between individual groups of patients: total cosine R to T (Control vs. MI: P = 4.3 x 10(-8), Control vs. VT/VF: P = 2.7 x 10(-16), MI vs. VT/VF: P = 3.1 x 10(-6)), percentage of loop area (Control vs. MI: P = 0.07, Control vs. VT/VF: P = 1.1 x 10(-8), MI vs. VT/VF: P = 2.9 x 10(-5), all nonparametric Mann-Whitney test). The comparisons of cumulative histograms also revealed significant differences between all three groups for both parameters (Kruskal-Wallis ANOVA test). Thus, these numerical descriptors of T-wave morphology are powerful indicators of arrhythmic complications among patients with ischaemic heart disease. They also differentiate between patients with stable uncomplicated ischaemic heart disease and healthy controls.

Promotion of adhesion and migration of RPE cells to provisional extracellular matrices by TNF-alpha.

PURPOSE: Adhesion and migration of retinal pigment epithelial (RPE) cells to provisional extracellular matrices (ECM) is important in the development of epiretinal membranes found in proliferative vitreoretinopathy (PVR). Tumor necrosis factor alpha (TNF-alpha) is found in PVR membranes and regulates many functions of RPE cells. In this study, the effects of TNF-alpha on adhesion and migration of RPE cells to various components of ECM were examined and elucidation of the mechanism of the response was attempted. METHODS: Mitogen activated protein kinase (ERK1/2; MAPK) activation was measured by immunoblot. RPE cells pretreated with TNF-alpha (10 ng/ml) or TNF-alpha + PD98059 (a specific inhibitor of MAPK, 30 microM) for 24 hours were compared with control RPE. Attachment was measured by modified MTT assay on fibronectin and collagen types I and IV. Spreading was measured by staining with fluo3-AM and confocal laser scanning microscopy. Migration of RPE cells on substrates was determined by Boyden chamber assay using PDGF-BB (20 ng/ml) as a chemotactic factor. Integrin expression was determined by flow cytometry and RT-PCR. RESULTS: TNF-alpha rapidly activated MAPK and increased the extent of attachment, spreading and migration on fibronectin and collagen type I (P < 0.01) but not on collagen type IV. TNF-stimulated RPE cells showed increased mRNA and surface protein expression for alpha1 and alpha5 integrin (P < 0.01) but not alpha3 integrin subunit. Neutralizing the anti-alpha1 antibody inhibited migration on collagen type I, whereas alpha5 antibody inhibited fibronectin-induced migration. Treatment with both TNF and PD98095 reduced attachment and migration on provisional ECM and reduced the upregulated integrin expression to control levels. CONCLUSIONS: After treatment with TNF-alpha, there is increased expression of specific integrins associated with increased adhesion and migration on provisional ECM (fibronectin and collagen type I). This effect is mediated, at least in part, by activation of MAPK signaling pathway.

Peroxisome proliferator-activated receptor-gamma ligands inhibit choroidal neovascularization.

PURPOSE: To determine the antiangiogenic effects of peroxisome proliferator-activated receptor (PPAR)-gamma agonists on ocular cells involved in the pathogenesis of choroidal neovascularization (CNV) in vitro and on experimental laser photocoagulation-induced CNV in vivo. METHODS: PPAR-gamma expression in human retinal pigment epithelial (RPE) cells and bovine choroidal endothelial cells (CECs) was determined using an RNase protection assay and Western blot analysis. Two PPAR-gamma ligands, troglitazone (TRO) and rosiglitazone (RSG; 0.1-20 microM), were used to assess effects on RPE and CEC proliferation and migration and CEC tube formation in response to vascular endothelial growth factor (VEGF). The effects of intravitreal injection of TRO on laser photocoagulation-induced CNV lesions in rat eyes (15 experimental, 15 control, nine burns per eye) and cynomolgus monkey eyes (two experimental, two control, seven paramacular burns per eye) was assessed by fluorescein angiography and histologic evaluation. RESULTS. PPAR-gamma1 was expressed in both RPE and CEC. PPAR-gamma ligands significantly inhibited VEGF-induced migration and proliferation in both cell types and tube formation of CEC in a dose-response manner. CNV in rats was markedly inhibited by intravitreous injection of TRO (P < 0.001). Lesions showed significantly less fluorescein leakage and were histologically thinner in the TRO-treated animals. Similar findings were present in the TRO-treated lesions in two monkey eyes. The drug showed no apparent adverse effects in the adjacent retina or in control eyes. CONCLUSIONS: The inhibition of VEGF-induced choroidal angiogenesis in vitro, and CNV in vivo by PPAR-gamma ligands suggests the potential application of these agents in the large group of patients with age-related macular degeneration complicated by CNV.

Selective killing of RPE with a vascular endothelial growth factor chimeric toxin.

PURPOSE: To determine the sensitivity of retinal pigment epithelial (RPE) cells to a vascular endothelial growth factor (VEGF) chimeric toxin. METHODS: A targeted toxin was developed using recombinant methods to fuse VEGF165 to the diphtheria toxin (DT) translocation and enzymatic domain (DT390-VEGF165). Human RPE cells, choroidal endothelial cells (CECs), and scleral fibroblasts were isolated, and a dose-response for DT390-VEGF165 was determined by measurement of cell proliferation and cell number. In parallel experiments, cultures were pretreated with transforming growth factor (TGF)-beta2. VEGF-receptor (VEGFR-1 and -2) expression was determined using reverse transcription-polymerase chain reaction and fluorescence-activated cell sorting, and affinity was measured using Scatchard analysis. RESULTS: RPE cells and CECs were similarly prone to killing by the VEGF-toxin, but scleral fibroblasts were unaffected. Pretreatment with TGF-beta2 selectively increased the sensitivity of RPE cells to the VEGF-toxin. RPE cells expressed both VEGFR-1 and -2 in vitro; however, the expression of VEGFR-1 was very low. Pretreatment with TGF-beta2 (10 ng/ml) was associated with increased expression of the VEGFR-1 in RPE cells and increased receptor affinity for VEGF detected by Scatchard analysis. CONCLUSIONS: Dose-dependent killing of RPE cells by the DT390-VEGF165 conjugate is selectively enhanced by pretreatment with TGF-beta2. This study provides further strong support for the presence of functional VEGFRs on human RPE cells, and demonstrates for the first time the ability to target a normal nonendothelial cell type through VEGFR expression.

The possibility of gene therapy for the treatment of choroidal neovascularization.

PURPOSE: Choroidal neovascularization (CNV) is responsible for most cases of severe visual loss in age-related macular degeneration. Recently, the possibility of gene therapy has been proposed for the treatment of CNV. The purpose of this study was to examine the feasibility of ex vivo and in situ gene therapy approaches for CNV. DESIGN: Experimental study. METHODS: Human retinal pigment epithelial (RPE) cells were transduced with a retroviral vector coding for beta-galactosidase. Transduced cells were grown on type II collagen sheets and transplanted under the retina of 20 rabbits. Animals were observed for 3 to 56 days, and transplanted cells were examined histologically and with X-gal staining. Bovine choroidal endothelial cells (CEC) were transduced with retroviral vectors coding for tissue inhibitor of metalloproteinase-2 (TIMP-2) or control vector. Production of TIMP-2 by transduced cells was determined by immunohistochemical analysis and enzyme-linked immunosorbent assay. Effect of transduction on in vitro proliferation, migration, and tube formation was examined in response to vascular endothelial growth factor (VEGF). Four CNV lesions were induced in one cynomolgus monkey by laser photocoagulation. Two days later, retroviral vector coding for TIMP-2 or control vector was injected into the subretinal space overlying the CNV lesions. The monkey was observed for 12 weeks using fluorescein angiography. RESULTS: Transplantation of transduced RPE cells was technically achieved in 10 of 20 animals. In these animals, RPE cells at the site of transplantation formed a monolayer and expressed beta-galactosidase for 14 days. beta-Galactosidase-positive cells were not identified at 56 days. Choroidal endothelial cells transduced with TIMP-2 secrete TIMP-2 into the media and show decreased migration and tube formation in vitro. In the in vivo monkey model, the control CNV lesions (n = 2) showed prominent leakage, whereas the experimental lesions (n = 2) showed minimal hyperfluorescence. CONCLUSIONS: Retrovirally transduced RPE cells survive in the subretinal space for at least 14 days and continue to express the gene product coded for by the vector. Choroidal endothelial cells retrovirally transduced for TIMP-2 produce TIMP-2 in vitro and show decreased angiogenic responses in vitro in response to VEGF. A preliminary study attempting in situ delivery of TIMP-2 vector to CNV lesions in a monkey eye supports the feasibility of this approach and encourages further study.

Natural history of choroidal neovascularization induced by vascular endothelial growth factor in the primate.

BACKGROUND: A new model of choroidal neovascularization (CNV) has been developed in the primate by implanting vascular endothelial growth factor (VEGF)-impregnated microspheres in the subretinal space. METHODS: CNV was induced in Macaca mulatta monkeys by implanting VEGF-impregnated gelatin microspheres in the subretinal space. Progression of CNV was followed for 24 weeks after surgery using fluorescein angiography. Eyes were enucleated at various time points, and lesions were evaluated for evidence of CNV by light microscopy and by immunohistochemical staining. RESULTS: CNV developed in 12 (92%) of 13 eyes. Fluorescein leakage was first observed in the 2nd postoperative week and was apparent for the following 12 weeks. CD31 staining for endothelial cells was first observed at day 7 and was evident for the following 8 weeks. Glial fibrillary acidic protein staining revealed a glial adhesion between the proliferative membrane and the retina at 6 weeks after implantation. Smooth muscle actin-positive cells were found a +2 weeks and remained prominent for at least the next 6 weeks. Cytokeratin-positive retinal pigment epithelial (RPE) cells, first identified in the proliferative membrane at day 3, predominated throughout the growth of the membrane. Macrophages (RAM-II positive) were present at day 3 but were no longer observed after day 7. CONCLUSION: In monkeys, subretinal implantation of VEGF-impregnated gelatin microspheres leads to the development of CNV. Early, disciform and reparative stages of CNV were observed, similar to those seen in humans. This model will be useful for studying the pathogenesis of CNV and for evaluating potential treatment strategies.

Noninvasive assessment of Wedensky modulated signal-averaged electrocardiograms.

Subthreshold stimulation without capture reduces the stimulation threshold and changes the action potential of subsequent suprathreshold stimulation, a phenomenon known as Wedensky modulation (WM). Patients with ventricular tachycardia (VT) inducible during electrophysiological testing (n = 47, mean age 63 +/- 13 years, 83% men), and healthy controls (n = 30, mean age 44 +/- 16 years, 60% men) were subjected to transthoracic external subthreshold stimulation between surface precordial and left subscapular patch electrodes. Stimuli of 5, 10, 20, and 40 mA were delivered for 2 ms, in synchrony with, or 20 ms after, R wave detection. A total of 60-200 subthreshold stimulated QRS complexes were averaged and compared with averaged nonstimulated complexes recorded during the same experimental session. To detect transient changes within the QRS complex, both signals were decomposed with 54 scales of Morlet analyzing wavelets (central frequencies 40-250 Hz). Wavelet vector magnitude was obtained for stimulated and nonstimulated complexes. Their difference created a wavelet residuum (WR) that characterized WM numerically. The surface area of the three-dimensional envelope of WR was measured and statistically compared between VT patients and healthy controls. WR showed a significantly greater increase in the spectral power of the stimulated complex in healthy controls than in VT patients (P < 0.01). In conclusion, (1) wavelet decomposition is a suitable tool to analyze WM, (2) WM in the late QRS complex is short, and (3) VT patients are less sensitive to WM, particularly at low subthreshold energies.

The pathogenesis of choroidal neovascularization in patients with age-related macular degeneration.

Laser photocoagulation and several experimental treatments for choroidal neovascularization (CNV) in patients with age-related macular degeneration attempt to ablate the neovascularization, but do not address underlying angiogenic stimuli. As a result, recurrences are a major problem. Drug treatment to counter the growth of CNV would be a major advance, but its development is impeded by lack of knowledge concerning the stimuli and other molecular signals involved in the pathogenesis of CNV. Herein we explore clues that can be gleaned from clinical, epidemiological, pathological, and experimental data. These suggest that abnormalities of the extracellular matrix of retinal pigmented epithelial (RPE) cells may promote a pro-angiogenic RPE phenotype that contributes to the development of CNV. This provides a general hypothesis that can be tested, but it is also necessary to test hypotheses regarding the specific alterations in gene expression that contribute to CNV. Identification of alterations in gene expression will provide targets for rational design of drug treatment.

The antidepressant hypericin inhibits progression of experimental proliferative vitreoretinopathy.

PURPOSE: Hypericin, a polycyclic dione used as an antidepressant, has been shown to inhibit the protein kinase C (PKC) pathway. Many of the pathologic responses found in proliferative vitreoretinopathy (PVR) are dependent upon PKC. Therefore, we studied the effect of hypericin on the treatment of experimental PVR. METHODS: PVR was induced in pigmented rabbits by intravitreal injection of 50,000 rabbit conjunctival fibroblasts after vitrectomy. Subsequently, the eyes received an intravitreal injection of either balanced salt solution (BSS, 0.1 mL) (group A, control) or hypericin (0.1 mL) in doses of 1 muM (group B), 10 muM (group C), and 100 muM (group D). The eyes were examined ophthalmoscopically on days 1, 3, 7, 14, and 28 after surgery and the stage of PVR was evaluated (0 to V). The effect of hypericin on retinal morphology and function was also determined for the eyes injected with 100 muM hypericin with no fibroblasts by light microscopy and electroretinogram (ERG). RESULTS: In the control eyes, the retina was detached after 5 days, membranes had formed on and beneath it, and the PVR had progressed to higher stages over time. In the eyes injected with hypericin, the PVR also progressed; however, the severity of PVR on each day was lower than that in control eyes on that day. PVR was significantly inhibited in groups C and D as compared with the control eyes after day 5 (P < 0.05). Histological examination of the hypericin-treated control eyes disclosed no morphological change, and ERG analysis revealed no significant functional change. CONCLUSIONS: Intravitreal injection of hypericin is a safe and effective means of reducing experimental PVR.