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Retina example

The vibronic coupling model has been applied to a number of molecular systems, and used to evaluate the behavior of wavepackets over coupled surfaces [191]. Recent examples are the radical cation of allene [192,193], and benzene [194] (for further examples see references cited therein). It has also been used to explain the lack of structure in the S2 band of the pyrazine absoiption spectrum [109,173,174,195], and recently to study the photoisomerization of retina] [196],... [Pg.288]

Methanol intoxication can cause blindness due to damage to ganglion cells in the retina. The blindness results from the accumulation of formaldehyde and formic acid, which are metabolites of methanol. Chemical compounds can also damage the visual cortex, for example, visual damage was observed among the victims of organic mercury intoxication in Japan (the fishermen of Minamata Bay). ... [Pg.293]

The RUI method is a modification of the brain uptake index method [29] which was first described by Aim and Tornquist [4], The RUI approach consists of a single-arterial (e.g., intracarotid) injection technique, where the primary objective is to analyze the influx of the test substrate from the circulating blood to the retina through the BRB (i.e., blood-to-retina direction). This approach, for example, has been used to determine the retinal uptake of the test substrate which has a relatively high permeability across the BRB. The advantage of this approach is that it avoids the effect of plasma-protein binding of the test substrate and allows the retinal uptake of the test substrate... [Pg.327]

An example of RUI analysis method using [3H]adenosine is shown in Figure 14.3B. The RUI value of [3H]adenosine is greater than that of [3H]d-mannitol (used as a paracellular transport marker) and significantly reduced by 30% in the presence of 2 mM unlabeled adenosine and thymidine, while 2 mM cytidine has no effect. Thus, the nature of the inhibition shown by this approach confirms the carrier-mediated transport of adenosine from the blood to the retina across the BRB in vivo [27],... [Pg.328]

Currently, there is only one antisense drug on the market— Vitravene (active ingredient fomivirsen) for the treatment of cytomegalovirus (CMV)-induced retinitis (inflammation of the retina) in AIDS patients. Fomivirsen has 21 nucleotides complementary to a CMV mRNA sequence, which is necessary for the production of infectious virus. Two examples of experimental antisense drugs are provided in Exhibit 3.15, while Table 3.1 lists other antisense drugs in clinical phase. [Pg.81]

A second example of inherited predisposition to cancer is provided by hereditary retinoblastoma. This is a rare tumor of the retina and, when it develops, it generally develops in one eye only. Nonetheless, in children with hereditary retinoblastoma, the cancer develops early in life and generally in both eyes. This is a striking example of the inherited predisposition to develop a tumor. As in the case of hereditary polyposis, the defect is in a tumor suppressor gene, in this case RBI. Here too patients have just one intact gene in each of their cells and a single mutation in that gene may be aU that is required to initiate tumor development. [Pg.340]

Schibler A suggestion. What you would like to do is knock out cr3rptochromes in the ganglion cells of the retina. This is difficult. However, what you may be able to do is to rescue the knockout mice with a transgene expressed in the SCN, for example. [Pg.43]

Van Gelder Again, how these different pigments play into the different output pathways is not clear. For example, in the pupillary light responsiveness we see a marked diminution in pupillary response comparing wild-type to rd rd mice. We see no diminution in phase-shifting response for entrainment in these animals. This means that, for pupillary responses, 90% of the response is driven by the outer retina, whereas for circadian responses it may be that none or only a small fraction is normally mediated by the outer retina. [Pg.44]

Physiological studies have identified both post- and presynaptic roles for ionotropic kainate receptors. Kainate receptors contribute to excitatory post-synaptic currents in many regions of the CNS including hippocampus, cortex, spinal cord and retina. In some cases, postsynaptic kainate receptors are codistributed with AMPA and NMDA receptors, but there are also synapses where transmission is mediated exclusively by postsynaptic kainate receptors for example, in the retina at connections made by cones onto off bipolar cells. Extrasynaptically located postsynaptic kainate receptors are most likely activated by spill-over glutamate (Eder et al. 2003). Modulation of transmitter release by presynaptic kainate receptors can occur at both excitatory and inhibitory synapses. The depolarization of nerve terminals by current flow through ionotropic kainate receptors appears sufficient to account for most examples of presynaptic regulation however, a number of studies have provided evidence for metabotropic effects on transmitter release that can be initiated by activation of kainate receptors. The hyperexcitability evoked by locally applied kainate, which is quite effectively reduced by endocannabinoids, is probably mediated preferentially via an activation of postsynaptic kainate receptors (Marsicano et al. 2003). [Pg.256]

This is an example of a real rolling tamponade, which has the advantage that no area of the retina is permanently separated from aqueous contact. [Pg.430]

Excellent question. Their atmosphere is hazy and attenuates light. Those parts of the creature s sides that are farther from the viewer s eye get dimmer. Close parts are brighter and clearer. Don t forget that our own retina is a 2-D surface, yet we can distinguish all sorts of objects for example, we can tell the difference between a sphere and a disc simply by their shading. ... [Pg.25]


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