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Nd:YAG membranotomy is a non-invasive, office-based treatment option that may be successfully used to treat premacular hemorrhage secondary to valsalva retinopathy.

The electroretinogram (ERG) provides a noninvasive, objective measure of retinal function, and is one of the most widely used diagnostic tools in the study of visual disorders. Although rodents are often used in the study of retinal disease, the properties of the flicker ERG of the rodent retina have not been fully characterized. Here, we show that the fundamental response of the rat ERG to sinewave flicker exhibited a low-pass pattern in the frequency range from 2 to 30 Hz, whereas the second harmonic (F2) showed a more complex frequency response relation. The F2 component represented only a small fraction of the ERG response at low temporal frequencies (below 12 Hz), but it made a substantial contribution to responses at high frequencies. The contrast-response relation was linear when tested with a low-frequency (6 Hz) stimulus, but saturated in response to a high-frequency (20 Hz) stimulus. After intravitreal injection of L-AP4, a specific blocker of the retinal ON pathway, the flicker responses elicited by either 6-or 20-Hz stimuli were greatly reduced in amplitude, whereas only a very slight enhancement was seen after the application of PDA, a drug that blocks retinal OFFpathway activity. Based on the observed differences in the degree of non-linearity, and contrastresponse properties of the rat flicker ERG at low and high frequencies, as well as the pharmacological results, we postulate that sustained and transient ON bipolar cells generate the flicker ERG responses elicited at low and high temporal frequencies, respectively. KeywordsElectroretinogram; flicker ERG; rodent; bipolar cell; pharmacology; sinusoidal stimuli; temporal frequencyThe electroretinogram (ERG) affords a quantitative, objective, and noninvasive method by which to examine light-evoked neuronal activity, and is commonly used to study the functional integrity of normal and diseased retinas. Decades of studies from a number of laboratories have provided a clearer understanding of the origins of the various potentials that summate to give rise to the ERG waveform elicited by a brief pulse of light (Penn and Hagins, 1969;Lamb and Pugh, 1992;Breton et al., 1994;Hood and Birch, 1997) Robson and Frishman, 1995; Hood and Birch, 1996). ERG responses elicited by flickering light stimuli, either to a series of pulses or to sinusoidally modulated light, have also been studied, and the results have provided (Krishna et al., 2002). In the present study, we characterized the flicker ERG responses elicited by sinusoidally modulated light from pigmented rat eyes under photopic conditions. Pharmacological tools were used to assess the contributions of ON and OFF retinal pathways to the responses elicited at low and high temporal frequencies, and special emphasis was placed on the analysis of nonlinearities (second harmonic response) and contrast-response relations.Adult pigmented Long Evans rats (both sexes, weight 250-500g) were used for this study. All experimental procedures conformed to the statement on animal care of the Association for Res...

Poliovirus 3AB protein is the first picornavirus protein demonstrated to have nucleic acid chaperone activity. Further characterization of 3AB demonstrates that the C-terminal 22 amino acids (3B region (also referred to as VPg), amino acid 88–109) of the protein is required for chaperone activity, as mutations in this region abrogate nucleic acid binding and chaperone function. Protein 3B alone has no chaperone activity as determined by established assays that include the ability to stimulate nucleic acid hybridization in a primer-template annealing assay, helix-destabilization in a nucleic acid unwinding assay or aggregation of nucleic acids. In contrast, the putative 3AB C-terminal cytoplasmic domain (C terminal amino acids 81–109, 3B + the last 7 C-terminal amino acids of 3A, termed 3B+7 in this report) possesses strong activity in these assays, albeit at much higher concentrations than 3AB. The characteristics of several mutations in 3B+7 are described here, as well as a model proposing that 3B+7 is the site of the “intrinsic” chaperone activity of 3AB while the 3A N-terminal region (amino acids 1–58) and/or membrane anchor domain (amino acids 59–80) serve to increase the effective concentration of the 3B+7 region leading to the potent chaperone activity of 3AB.