Temporal interactive response is resistant to cloudy ocular media in the slow double-stimulation multifocal electroretinogram.

Aim: To examine the influence of cloudy media on the slow double-stimulation multifocal electroretinogram (mfERG).

Methods: Slow double-stimulation mfERG responses were measured from 26 subjects with normal ocular health under normal and light scattering conditions (induced using acrylic sheets) (Experiment 1) and another nine cataract patients before and after cataract surgery (Experiment 2). The amplitudes and implicit times of the first (M(1)) and second (M(2)) stimulation were compared under normal and light scattering conditions in Experiment 1 and they were compared under precataract and postcataract surgery in Experiment 2.

Luminance-modulated adaptation in the global flash mfERG: a preliminary study of early retinal functional changes in high-risk glaucoma patients.

Purpose: To investigate the association of the luminance-modulation global flash multifocal electroretinogram (mfERG) and other clinical assessments of vision in subsets of subjects at high risk of developing glaucomatous damage.

Methods: Eighteen subjects (28 eyes) with asymmetric glaucoma and ocular hypertension were measured in this longitudinal study of visual field, OCT, and multifocal electroretinogram (mfERG). Five ophthalmic examinations were scheduled, once every 12 months over a 4-year period.

Effect of inner retinal dysfunction on slow double-stimulation multifocal electroretinogram.

Purpose: This study investigated the retinal adaptive mechanism in inner retinal dysfunction using the slow double-stimulation multifocal electroretinogram (mfERG) paradigm.

Methods: Slow double-stimulation mfERG responses were recorded from 15 eyes of 15 4-month-old Mongolian gerbils in control conditions and after suppression of inner retinal responses with injections of tetrodotoxin (TTX) and N-methyl-d-aspartic acid (NMDA). The stimulation consisted of five video frames: the two initial frames with multifocal flashes were triggered by two independent m-sequences, followed by three dark video frames.

Forward and backward adaptive effects in global flash multifocal electroretinogram stimulation.

Purpose: The present study investigated retinal adaptive responses in concert with the modulation of forward and backward adaptation induced by periodic global flashes using the global flash multifocal electroretinogram (mfERG).

Methods: Six normal subjects were recruited for global flash mfERG measurements, which consisted of 103 scaled hexagonal elements followed by a global flash frame. In experiments I and II, with constant luminance maintained in both local and global flash frames, the number of dark frames was independently varied and these frames were either inserted prior to or following the global flash frame to investigate the forward or backward adaptive effect of the global flash on the mfERG.

Detection of early functional changes in diabetic retina using slow double-stimulation mfERG paradigm.

Aim Diabetes mellitus (DM) is a systemic disease with insufficient secretion of insulin or poor response to insulin. This typically causes poor control of blood glucose level leading to a range of complications. Early detection of the retinal function alteration in DM is needed.

Impairment of retinal adaptive circuitry in the myopic eye.

Previous studies have proposed that the inner retina is affected in myopes. This study aimed to investigate the changes in adaptive circuitry of the inner retina in myopia, using the global flash multifocal electroretinogram (global flash mfERG) with different levels of contrast (luminance modulation). Fifty-four myopes had global flash mfERG recorded with different contrasts.

Porcine global flash multifocal electroretinogram: possible mechanisms for the glaucomatous changes in contrast response function.

Purpose: The aim of this study was to obtain a better understanding of the cellular contributions to the porcine global flash mfERG by using a pharmacologic dissection method, together with the method using variation of stimulus contrast which has been used to demonstrate mfERG changes in human glaucoma.

Methods: Global flash mfERGs with different stimulus-contrast settings (99%, 65%, 49% or 29%) were recorded from 14 eyes of ten 6-week-old Yorkshire pigs in control conditions and after suppression of inner retinal responses with inhalation of isoflurance (ISO), and injections of tetrodotoxin (TTX) and N-methyl-d-aspartic acid (NMDA). ON- and OFF-pathway responses were isolated by injection of 2-amino-4-phosphonobutyric acid (APB) and cis-2,3-piperidinedicarboylic acid (PDA).

The characteristics of multifocal electroretinogram in isolated perfused porcine eye: cellular contributions to the in vitro porcine mfERG.

We investigated characteristics of multifocal electroretinograms (mfERG) from in vitro perfused porcine eyes. TTX, NMDA, APB, and PDA were used to identify contributions to the mfERG from inner retinal neurons, ON-pathway, OFF-pathway, and photoreceptors. The cellular contributions of the first-order kernel (K1) in an isolated perfused porcine mfERG came from both inner and outer retina, and were similar to those of in vivo porcine mfERG.

Multifocal electroretinogram in rhodopsin P347L transgenic pigs.

Purpose: Neural ectopic rewiring in retinal degeneration such as retinitis pigmentosa (RP) may form functional synapses between cones and rod bipolar cells that cause atypical signal processing. In this study, the multifocal electroretinograms (mfERGs) of a large animal model of RP, the rhodopsin P347L transgenic (Tg) pig, were measured to examine the sources and nature of altered signal processing.

Methods: mfERG responses from a 6-week-old Tg pig were recorded before and after sequential application of tetrodotoxin (TTX), N-methyl-D-aspartate (NMDA), 2-amino-4-phosphonobutyric acid (APB), and cis-2,3-piperidinedicarboylic acid (PDA), to identify contributions to the retinal signal from inner retinal neurons, the ON-pathway, the OFF-pathway, and photoreceptors.

Pharmacologically defined components of the normal porcine multifocal ERG.

Multifocal electroretinograms (mfERG) from isoflurane anesthetized pigs were recorded and sequential application of TTX, NMDA, APB and PDA were used to identify contributions to the mfERG from inner retinal neurons, ON-pathway, OFF-pathway and photoreceptors. The cellular origins of the first-order kernel (K1) and the first slice of the second-order kernel (K2.1) porcine mfERG are contributed from both inner and outer retina.

Construction of multiporphyrin arrays using ruthenium and rhodium coordination to phosphines.

The synthesis of linear multiporphyrin arrays with mono- and bisphosphine-substituted porphyrins as ligand donors and ruthenium(II) or rhodium(III) porphyrins as ligand acceptors is described. With appropriate amounts of the building blocks mixed, linear dimeric and trimeric arrays have been synthesized and analyzed by (1)H NMR and (31)P NMR spectroscopy. The Ru/Rh acceptor porphyrins can be located either at the periphery or in the center of the array.

Phosphine and phosphonite complexes of a ruthenium(II) porphyrin. 1. Synthesis, structure, and solution state studies.

We have investigated the effect of complexation of different phosphorus ligands on the stability, solid state structure, and spectroscopic properties (NMR, IR, UV-vis) of a 5,15-diphenyl-substituted ruthenium porphyrin, (MeOH)Ru(II)(CO)(DPP) 2 [DPP = 5,15-bis(3',5'-di-tert-butyl)phenyl-2,8,12,18-tetraethyl-3,7,13,17-tetramethylporphyrin]. The ligands used are PPh(3), diphenyl(phenylacetenyl)phosphine (DPAP), bis(diphenylphosphino)acetylene (DPPA), tris(phenylacetenyl)phosphine [(PA)(3)P], and diethyl (phenylacetenyl)phosphonite [PAP(OEt)(2)]. The mono-phosphine complexes (PR(3))Ru(II)(CO)(DPP) are readily formed in solution in quantitative yields.

Amplification of a cyclic mixed-metalloporphyrin tetramer from a dynamic combinatorial library through orthogonal metal coordination.

A cyclic porphyrin tetramer, consisting of two bis-phosphine substituted zinc(II) porphyrin units and two Rh(III)TPP units, is selected and amplified virtually quantitatively from a dynamic combinatorial library using 4,4'-bipy as a scaffold and using orthogonal binding modes.

Identification and Isolation of a Receptor for N-Methyl Alkylammonium Salts: Molecular Amplification in a Pseudo-peptide Dynamic Combinatorial Library.

A cyclic pseudo-peptide receptor for acetylcholine has been amplified and isolated from a dynamic combinatorial library by virtue of templated stabilization under thermodynamic control (see scheme, TFA=trifluoroacetic acid). This is a demonstration of significant molecular amplification in dynamic systems to evolve a novel receptor.