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At least 667 records · Page 37Linked to original sources
PubMed2003

Distribution of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate-type glutamate receptor subunits (GluR2/3) along the ventral visual pathway in the monkey.

By using immunohistochemical methods, we examined the distribution of cells expressing subunits of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA)-selective glutamate receptors (GluR2/3) in the cortical areas of the occipitotemporal pathway in monkeys. GluR2/3-immunoreactive (-ir) cells were primarily pyramidal cells; this category, however, also included large stellate cells in layer IVB of the striate cortex (V1) and fusiform cells in layer VI of all the areas examined. GluR2/3 immunoreactivity differed among the areas in laminar distribution and intensity. In V1, GluR2/3-ir cells were identified mainly in layers II, III, IVB, and VI. The prestriate areas V2 and V4 and the inferior temporal areas TEO and TE contained GluR2/3-ir cells in layers II, III, and VI. In the TE, GluR2/3-ir cells were also abundant in layer V. In area 36 of the perirhinal cortex, neurons in layers II, III, V, and VI were labeled in a similar manner to the TE labeling, but with greater staining intensity and numbers, especially in layer V. Thus, GluR2/3 immunoreactivity increased rostrally along the pathway. Within V1 and V2, cells strongly stained for GluR2/3 formed clusters that colocalized with cytochrome oxidase (CO)-rich regions. These distinct laminar and regional distribution patterns of GluR2/3 expression may contribute to the specific physiological properties of neurons within various visual areas and compartments.

Animals↗
PubMed2000

Distinct membrane domains on endosomes in the recycling pathway visualized by multicolor imaging of Rab4, Rab5, and Rab11.

Two endosome populations involved in recycling of membranes and receptors to the plasma membrane have been described, the early and the recycling endosome. However, this distinction is mainly based on the flow of cargo molecules and the spatial distribution of these membranes within the cell. To get insights into the membrane organization of the recycling pathway, we have studied Rab4, Rab5, and Rab11, three regulatory components of the transport machinery. Following transferrin as cargo molecule and GFP-tagged Rab proteins we could show that cargo moves through distinct domains on endosomes. These domains are occupied by different Rab proteins, revealing compartmentalization within the same continuous membrane. Endosomes are comprised of multiple combinations of Rab4, Rab5, and Rab11 domains that are dynamic but do not significantly intermix over time. Three major populations were observed: one that contains only Rab5, a second with Rab4 and Rab5, and a third containing Rab4 and Rab11. These membrane domains display differential pharmacological sensitivity, reflecting their biochemical and functional diversity. We propose that endosomes are organized as a mosaic of different Rab domains created through the recruitment of specific effector proteins, which cooperatively act to generate a restricted environment on the membrane.

Androstadienes↗
PubMed1978

An evaluation of gliomas of the anterior visual pathways. A 10-year survey.

Thirteen cases of the childhood type of optic glioma from a 10-year period were studied. Particular attention was paid to the pre-operative neuro-ophthalmological and radiological findings. The patients all underwent explorative craniotomy when biopsy specimens were removed for histopathological study. Post-operative radiotherapy was given in 12 cases. In the follow-up period five patients showed deterioration of visual function, three patients showed unchanged visual function, and one patient showed improved visual function. In the remaining four patients, visual function could not be adequately determined. Three patients died in the course of the follow-up period. Retrospectively it was possible, on a histopathological basis, to divide the patients into three groups. It is suggested that the future management of these patients should consist of explorative craniotomy with diagnostic biopsy. Radiotherapy should be confined to selected cases, as only a minority of optic gliomas are radiosensitive.

Adolescent↗
PubMed2001

The effects of 1 week of REM sleep deprivation on parvalbumin and calbindin immunoreactive neurons in central visual pathways of kittens.

Many maturational processes in the brain are at high levels prenatally as well as neonatally before eye-opening, when extrinsic sensory stimulation is limited. During these periods of rapid brain development, a large percentage of time is spent in rapid eye movement (REM) sleep, a state characterized by high levels of endogenously produced brain activity. The abundance of REM sleep in early life and its ensuing decline to lower levels in adulthood strongly suggest that REM sleep constitutes an integral part of the activity-dependent processes that enable normal physiological and structural brain development. We examined the effect of REM sleep deprivation during the critical period for visual development on the development of two calcium-binding proteins that are associated with developmental synaptic plasticity and are found in the lateral geniculate nucleus (LGN) and visual cortex. In this study, REM sleep deprivation was carried out utilizing a computer-controlled, cage-shaking apparatus that successfully suppressed REM sleep. Body weight data suggested that this method of REM sleep deprivation produced less stress than the classical multiple-platform-over-water method. In REM sleep-deprived animals with normal binocular vision, the number of parvalbumin-immunoreactive (PV) neurons in LGN was found to be lower compared with control animals but was not affected in visual cortex. The pattern of calbindin-immunoreactivity (CaB) was unchanged at either site after REM sleep deprivation. Parvalbumin-immunoreactivity develops later than calbindin-immunoreactivity in the LGN, and the REM sleep deprivation that we applied from postnatal day 42-49 delayed this essential step in the development of the kitten's visual system. These data suggest that in early postnatal brain development, REM sleep facilitates the usual time course of the expression of PV-immunoreactivity in LGN neurons.

Animals↗
PubMed2006

Spatiotemporal reaction kinetics of an ultrafast photoreaction pathway visualized by time-resolved liquid x-ray diffraction.

We have studied the reaction dynamics for HgI(2) in methanol by using time-resolved x-ray diffraction (TRXD). Although numerous time-resolved spectroscopic studies have provided ample information about the early dynamics of HgI(2), a comprehensive reaction mechanism in the solution phase spanning from picoseconds up to microseconds has been lacking. Here we show that TRXD can provide this information directly and quantitatively. Picosecond optical pulses triggered the dissociation of HgI(2), and 100-ps-long x-ray pulses from a synchrotron probed the evolving structures over a wide temporal range. To theoretically explain the diffracted intensities, the structural signal from the solute, the local structure around the solute, and the hydrodynamics of bulk solvents were considered in the analysis. The results in this work demonstrate that the determination of transient states in solution is strongly correlated with solvent energetics, and TRXD can be used as an ultrafast calorimeter. It also is shown that a manifold of structural channels can be resolved at the same time if the measurements are accurate enough and that global analysis is applied. The rate coefficients for the reactions were obtained by fitting our model against the experimental data in one global fit including all q-values and time delays. The comparison between all putative reaction channels confirms that two-body dissociation is the dominant dissociation pathway. After this primary bond breakage, two parallel channels proceed. Transient HgI associates nongeminately with an iodine atom to form HgI(2), and I(2) is formed by nongeminate association of two iodine atoms.

Journal Article↗
PubMed1981

Reduced contrast sensitivity in compressive lesions of the anterior visual pathway.

A clinical procedure for determining contrast sensitivity was performed on patients with suspected sella area masses. The test consisted of a series of six plates, each containing a bar pattern of fixed sinusoidal spatial frequency in which contrast varies along the length of the bar. Patients with compressive lesions of the chiasm of optic nerve showed loss of contrast sensitivity over the whole range of spatial frequencies. The general loss in contrast was evident even in patients with 20/20 Snellen acuity. After surgery, contrast sensitivity improved, as did other measures of vision, but significant contrast deficits remained. Contrast sensitivity is a sensitive indicator for the diagnosis and evaluation of compressive lesions of the chiasm.

Adult↗
PubMed2000

[Dependence of bioelectrical activity in occipital and frontal lobes and of the function of visual pathways from blood and oxygen supply].

The dependence of occipital and frontal lobes of the brain cortex bioelectrical activity and function from blood and oxygen supply was investigated in 626 minopic and 80 children and teenagers with normal vision. Myopia was found a natural model of blood and oxygen deprivation, of decrease of bioelectrical activity of frontal and partially occipital lobes, especially. The decrease of alpha-rythme index and alpha-waves amplitude was found on EEG of occipital lobes. Adaptation to hypoxia in the course of interval hypoxic training and the course of osteoreflex stimulation were proved to be reliable means for improving blood and oxygen supply of occipital and frontal lobes of the brain cortex, which was followed by normalization of EEG and vision: the sharpness of vision rose to 1.0-0.9 in 80% of children and in 60% of teenagers.

Adolescent↗