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Biomedical subjects

A Derouiche

Publications and source records attributed to A Derouiche.

At least 19 recordsLinked to original sources
PubMed2005

Nutritional intervention study with argan oil in man: effects on lipids and apolipoproteins.

AIM: To evaluate whether the consumption of virgin argan oil (VAO) is associated with a change in serum lipids and reduces the risk of cardiovascular disease in healthy Moroccans. METHODS: Sixty volunteers consumed butter (25 g/day) during 2 weeks (stabilization period) and were randomly divided into two groups: the treatment group received 25 g/day of VAO during 3 weeks (intervention period), and the control group received 25 g/day of extra virgin olive oil (EVO). Throughout the study, weight, blood pressure, and daily food intake were measured. Serum total cholesterol and low- and high-density lipoprotein cholesterol, triglycerides, and apolipoproteins A-I and B were measured at the end of each diet period. RESULTS: Analysis of food intake showed that the daily diet is isocaloric for the butter regimen (2,537 +/- 244 kcal/day) as well as for the VAO and EVO regimens (2,561+/- 246 and 2,560 +/- 253 kcal/day, respectively). Analysis of the lipid intake showed a reduction in saturated fatty acids with VAO and EVO regimens (27 +/- 1.4 and 26.4 +/- 3.4%, respectively) as compared with the stabilization period (41.6 +/- 2.4%). The analysis of serum lipids showed a significant increase in high-density lipoprotein cholesterol and apolipoprotein A-I in both VAO group (8.4%, p = 0.012, and 5.2%, p = 0.027, respectively) and EVO group (17.3%, p = 0.001, and 5.9%, p = 0.036, respectively). However, low-density lipoprotein cholesterol and apolipoprotein B (13.8%, p = 0.037, and 7.8%, p = 0.039, respectively) decreased significantly only in EVO group as compared with the stabilization period, while triglycerides decreased significantly by 17.5% (p = 0.039) only in VAO group. CONCLUSION: These results confirm the cholesterol-lowering effect of EVO and show for the first time the triglyceride-lowering effect of VAO in men.

Adult↗
PubMed2005

Colloidal aggregation in polymer blends.

We consider here a low-density assembly of colloidal particles immersed in a critical polymer mixture of two chemically incompatible polymers. We assume that, close to the critical point of the free mixture, the colloids prefer to be surrounded by one polymer (critical adsorption). As result, one is assisted to a reversible colloidal aggregation in the nonpreferred phase, due the existence of a long-range attractive Casimir force between particles. This aggregation is a phase transition driving the colloidal system from dilute to dense phases, as the usual gas-liquid transition. We are interested in a quantitative investigation of the phase diagram of the immersed colloids. We suppose that the positions of particles are disordered, and the disorder is quenched and follows a Gaussian distribution. To apprehend the problem, use is made of the standard phi(4) theory, where the field phi represents the composition fluctuation (order parameter), combined with the standard cumulant method. First, we derive the expression of the effective free energy of colloids and show that this is of Flory-Huggins type. Second, we find that the interaction parameter u between colloids is simply a linear combination of the isotherm compressibility and specific heat of the free mixture. Third, with the help of the derived effective free energy, we determine the complete shape of the phase diagram (binodal and spinodal) in the (Psi,u) plane, with Psi as the volume fraction of immersed colloids. The continuous "gas-liquid" transition occurs at some critical point K of coordinates (Psi(c) = 0.5,u(c) = 2). Finally, we emphasize that the present work is a natural extension of that, relative to simple liquid mixtures incorporating colloids.

Journal Article↗
PubMed2005

Kinetics of microphase separation in interpenetrated polymer networks in solution.

We present here a theoretical study of the early kinetics of the microphase separation in crosslinked polymer blends, made of two incompatible polymers A and B, dissolved in a common good solvent. Use is made of an extended blob model used previously for the investigation of the static properties of such a transition. We are interested in the variation of the relaxation rate, tau(q), versus the wave number q, in the vicinity of the spinodal temperature. We first show that kinetics is entirely dominated by local motions, which are of Rouse type. Slow motions are absent, because of the permanent presence of crosslinks. Second, we find that the characteristic frequency, omega (q) = tau(q)(-1), increases with increasing wave number q according to a sixth power law, that is omega (q) approximately q6 phi(-9/4), where phi is the overall monomer volume fraction. Therefore, the swelling of strands due to the excluded-volume forces leads to a renormalization of the characteristic frequency by a multiplicative factor scaling as phi(-9/4). The main conclusion is that the presence of a good solvent necessitates relaxation rates less important than those relative to crosslinked mixtures in the molten state.

Journal Article↗
PubMed2005

Kinetics of phase separation in ramified polymer blends of arbitrary topology.

We present here a theoretical study of kinetics of phase separation within a mixture made of two chemically incompatible ramified polymers. For simplicity, we assume that they have the same topology. We are interested in the variation of the relaxation rate, tau(q), versus the wave number q, in the vicinity of the spinodal temperature. The kinetics is governed by local (Rouse) and reptation motions (faster and slower modes). For qRG >> 1 (RG being the gyration radius), kinetics is entirely controlled by local motions where each chain moves inside its own tube, and we show that the corresponding characteristic frequency, tau(q)(-1), scales as tau(q)(-1) approximately kappaGq6, where kappaG is a known topological factor. For qR(G) << 1, however, kinetics is rather dominated by long-wavelength (reptation) motions where unlike ramified polymers creep inside a long tube. For this case, we find that tau(q)(-1) approximately delta (0) q2 (chi(c) - chi), where delta (0) is another known topological factor that represents the total mobility of free monomers belonging to connected chains and reticulation points, and chi(c) accounts for the critical value of the segregation parameter. Finally, the derived relaxation rate must be compared to that relative to a linear polymer mixture.

Journal Article↗
PubMed2004

Exact effective force between star-polymers in a Theta-solvent.

We re-examine here the computation of the effective force between two star-polymers of respective numbers of branches f(1) and f(2), immersed in a common Theta-solvent. Such a force originates essentially from the repulsive three-body interactions. To achieve this, we take advantage of some established results using renormalization theory for three-dimensional star-polymers, or conformal invariance for two-dimensional ones. We first show that, in dimension d = 3, the force, F(r), decreases with the center-to-center distance r as F(r)/kappa BT congruent with Af1f2 x [r ln (R2/r2]-1 (r<R), with the exact universal amplitude Af1f2 = f1f2(f1 + f2 - 2)/22. Second, in dimension d = 2, we find that the force decays more slowly as F(r)/kappa BT congruent with Bf1f2 x r-1 (r<R), with the exact universal amplitude Bf1f2. For high distances compared to the gyration radius, R approximately a square root of N, of a single polymer chain at the Theta-point, an exponential decay of the force is expected.

Journal Article↗
PubMed2001

Peripheral astrocyte processes: monitoring by selective immunostaining for the actin-binding ERM proteins.

Astrocytes extend thin lamellate processes in the neuropil, in particular around synapses, where they can modulate synaptic function or mediate glial-neuronal communication. Previous studies have shown that these lamellate perisynaptic processes change their shape in response to neuronal activity, but the underlying mechanisms have remained unclear. Similarly, the molecular composition of these fine, sheet-like astrocytic processes (often 50-100 nm wide) is not understood but has to be related to their dynamic properties. To this end, we have studied the presence of ezrin, radixin, and moesin (ERM proteins) in the rat hippocampus and in primary cultured astrocytes, applying immunoperoxidase, immunofluorescence, and immunogold techniques. These three ERM proteins are known as actin-binding proteins that link the cell membrane to the actin cytoskeleton, particularly in microvillus-bearing epithelial cells. In cell culture, anti-ezrin and antiradixin, but not antimoesin, antibodies were specific for astrocytes, which often displayed selective staining of filopodia and microvilli. Nonoverlapping visualization of astrocytic peripheral and stem processes was obtained by immunocytochemical double labeling for ezrin and GFAP, respectively. In sections of rat hippocampus, homogeneous labeling of the neuropil, but not of cell layers, resulted from immunostaining of fine, peripheral astrocyte processes, as confirmed ultrastructurally. Our data show that the fine peripheral processes of astrocytes, which also constitute the perisynaptic glial sheath, are specialized in that they contain characteristic actin-associated molecules, likely to contribute to their dynamic properties. Applying anti-ezrin and anti-radixin as selective markers, plasticity of these perisynaptic glial processes can be analyzed.

Actin Cytoskeleton↗
PubMed2001

[Retroperitoneal neuroblastoma in the adult: case report and review of the literature].

Retroperitoneal neuroblastoma is a rare embryonic tumor of the sympathetic nervous system that is specific to the child. In this study, the case is reported of an infant who underwent median laparotomy at the age of 14 months for a tumor which occupied the left half of the abdomen. The lesion was large, hard, and not very mobile. It was considered to be unresectable, and the histological findings after biopsy showed it to be a neuroblastoma. Radiotherapy was then initiated, which successfully reduced the tumor size. A second investigation at the age of three years detected an unresectable tumor of 5 cm. A further biopsy was performed, and the histological findings showed the lesion to be a partially developed ganglioneuroblastoma. The patient has been followed up regularly by ultrasonography which has shown no increase in tumor size. She is now 20 years old, and is asymptomatic. The last computed tomography scan visualized a 62-mm retroperitoneal mass with no metastases. Surgery was decided against in favor of regular monitoring. This case is particular due to the prolonged survival of the patient, regression of histological stage, and reduction in size of the tumor after radiotherapy. It is remarkable that the diagnosis of neuroblastoma was made when the patient was 14 months old, and that she is still alive at 20 years old.

Adult↗
PubMed2000

Topical correlation of increased hippocampal glutamine synthetase immunoreactivity and glutamatergic terminal fields after entorhinal cortex lesion.

Many astrocyte functions are related to glutamatergic transmission and to other synaptic functions, such as glutamate uptake and glutamate metabolism. While many of these functions can be executed by perisynaptic astrocyte processes, it is not clear how these processes are formed. One of the factors guiding them to the synapse may be synaptically released glutamate. This would explain the topical correlation between laminated glutamatergic terminal fields and laminae most intensely labeled by a cytoplasmic astrocyte marker, anti-glutamine synthetase (GS). This hypothesis was tested by selectively increasing the glutamate content in one terminal field. The rat entorhinal cortex, the origin of the glutamatergic projection to the outer molecular layer (OML) of the hippocampal fascia dentata, was lesioned electrolytically. In line with the hypothesis, GS immunoreactivity was strongly increased in the OML at 6 and 8 days postlesion. Lesion of only the medial entorhinal cortex resulted in heavily increased GS immunoreactivity only in the central portion of the molecular layer (i.e., the corresponding terminal field). The laminae affected were always separated from neighboring fields by a straight and clear-cut line. Although many other factors are released in the terminal field after lesion, the results are consistent with a guiding role for glutamate. The lamina-specific effect suggests that the factor(s) involved have a very limited diffusion distance. The straight border line between affected and unaffected laminae, which cuts across astrocyte territories, can best be explained by ramification of only those processes of a given astrocyte that are contained within the lamina affected.

Animals↗
PubMed2000

Ezrin immunoreactivity is associated with increasing malignancy of astrocytic tumors but is absent in oligodendrogliomas.

The actin-binding protein ezrin has been associated with motility and invasive behavior of malignant cells. To assess the presence of this protein in human glial cells of the brain and its potential role in benign and malignant glial tumors, we studied ezrin immunoreactivity (IR), proliferation (MIB-1-IR), and apoptosis (terminal dUTP nick-end labeling) in normal human brain tissues from 10 autopsies and tissues from 115 cases of human glial tumors including astro-cytomas, ependymomas, oligodendrogliomas, and glioblastomas. We found weak staining of peripheral processes in normal human brain astrocytes and in World Health Organization grade II benign astrocytomas. Staining was markedly increased in anaplastic astrocytomas (World Health Organization grade III) and clearly strongest in glioblastomas (World Health Organization grade IV). The increase of ezrin-IR correlated significantly with increasing malignancy of astrocytic tumors (P < 0.0001). Statistical analysis revealed a stronger association with increasing malignancy for ezrin-IR than for MIB-1-IR or terminal dUTP nick-end labeling staining. Ezrin-IR was absent in normal oligodendrocytes and in oligodendrogliomas, but pronounced in normal ependymal cells and ependymomas. Ezrin-IR seems to be specific for astrocytes and ependymal glia in the normal brain. Our results indicate that ezrin-IR may provide a useful tool for the distinction of oligodendrogliomas and astrocytomas and for the grading of astrocytic tumors.

Antigens, Nuclear↗
PubMed2000

Heme oxygenase-2 and nitric oxide synthase immunoreactivity of bovine olfactory receptor neurons and a comparison with the distribution of NADPH-diaphorase staining.

It has recently been suggested that, in addition to nitric oxide (NO), carbon monoxide (CO) is an important gaseous messenger which might be involved in vertebrate olfactory transduction because its effects include activation of guanylyl cyclase and the formation of cGMP. As there is no information regarding the presence of heme oxygenase-2 -- the constitutive isoform of the heme oxygenase system -- in olfactory neurons of non-rodent species, we have investigated the distribution pattern of heme oxygenase-2 in the olfactory epithelium of the bovine, a representative of macrosmatics. Localization of nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) activity of the olfactory epithelium was compared with heme oxygenase-2 and NO synthase (NOS) immunoreactivities in order to obtain possible hints at functional significance. NADPH-d activity was particularly intense in apical dendrites of receptor neurons. It was also found in Bowman glands and intraepithelial duct cells. Less intense, discrete NADPH-d activity was present also at intermediate and basal levels of the olfactory epithelium, corresponding to the layer of receptor neuron somata and basal cells. While heme oxygenase-2 activity mainly occurred in neuronal perikarya, a very intense NOS immunoreactivity, exclusively for the inducible isoform, was detected in the apical dendrites. Ultrastructurally, NADPH-d histochemistry showed distinct labelling of membranes, in particular of endoplasmic reticulum, mitochondria and nucleus. The coincident localization of the moderate NADPH-d activity and heme oxygenase-2 immunoreactivity in receptor cell perikarya suggest a functional association between NADPH-cytochrome P450 reductase and heme oxygenase-2. In contrast, dendritic localization of NADPH-d activity is topically and possibly functionally related to the presence of the inducible isoform of NOS. The results suggest that both CO and NO may be generated in bovine receptor neurons and thus involved in odorant stimulation. Based on immunocytochemical localization of synthesizing enzymes, NO might be regarded as a direct regulator of transduction related processes while CO might act as a modulator of the initial signal.

Animals↗
PubMed1999

Cortical neurons immunoreactive for the potassium channel Kv3.1b subunit are predominantly surrounded by perineuronal nets presumed as a buffering system for cations.

Perineuronal nets (PNs) are known as chondroitin sulphate-rich, lattice-like coatings of the extracellular matrix. In the cortex of mammalian species investigated so far, they were mainly found around GABAergic neurons, but to a lesser degree also around pyramidal cells. Previous investigations in the rat revealed similar distribution patterns of fast-firing neurons expressing both the Kv3.1b subunit of voltage-gated potassium channels and the calcium-binding protein parvalbumin. In the present study, triple fluorescence labelling was applied for the simultaneous demonstration of PNs with the N-acetylgalactosamine-specific Wisteria floribunda agglutinin (WFA), parvalbumin-immunoreactivity (ir) with a monoclonal antibody and of Kv3.1b-ir with several rabbit antibodies. Subsets of non-pyramidal neurons - enwrapped by PNs and expressing parvalbumin and Kv3.1b - were detected in the rat and monkey neocortex and hippocampus. In the rat, faintly stained PNs were additionally found around several layer II/III and V pyramidal cells immunonegative for Kv3.1b, but contacted by Kv3.1b-containing boutons. In the monkey, more intensely labelled PNs frequently occurred around pyramidal cells which themselves appeared to be Kv3. 1b-immunopositive. We also observed minor Kv3.1b-ir and parvalbumin-ir cortical cell populations which were devoid of PNs; occasionally, nets were detected around neurons lacking both immunoreactivities. By confocal laser scanning microscopy, Kv3.1b-ir and WFA-binding sites were found adjoining at the soma and proximal dendritic surface, while lectin-binding sites usually extended on more distal dendritic segments and the axon initial segments which failed to express detectable Kv3.1b-ir. This spatial relationship of both markers was also confirmed by combined WFA-gold labelling and Kv3.1b-immunoperoxidase staining at the electron microscopic level. The data are used for a critical examination of current hypotheses concerning the functional role of PNs. We conclude that PNs may serve as rapid local buffers of excess cation changes in the extracellular space. Somatic membranes of fast-spiking neurons seem to be a main, but not the only source of such changes.

Animals↗
PubMed1999

The dopamine D2 receptor subfamily in rat retina: ultrastructural immunogold and in situ hybridization studies.

Dopamine, a major neurotransmitter in the vertebrate retina, is released from interplexiform cells and a restricted subset of amacrine cells. Dopamine effects vary between different retinal cell types, most likely due to differences in cell-specific receptor subtype expression. Identification of cells expressing receptors of the D2-subfamily (D2R, D3R, D4R) on a light microscopical level has rendered equivocal results, and no information is as yet available concerning the subcellular distribution of receptor protein. In the present study, D2R and D2/3R subtype-specific antisera, and D2R-, D3R- and D4R-specific oligonucleotide probes were used for ultrastructural and in situ hybridization analyses of the receptor subtype distribution in the rat retina. Light and electron microscopy showed that in addition to the known localization of intense D2R-immunoreactivity in all dopaminergic cells immunoreactive for tyrosine hydroxylase (TH), homogeneous, less intense D2R-immunoreactivity was also seen throughout the inner plexiform layer (IPL). Ultrastructurally, many additional amacrine cell processes devoid of TH-immunoreactivity at all levels of the inner plexiform layer were immunoreactive. D2R-immunoreactivity was found mainly on intracellular vesicles, and immunoreactivity associated with the plasma membrane was always extrasynaptic. No D2R-immunoreactivity was found in amacrine cell somata postsynaptic to the so-called dopaminergic 'ring endings'. Many D2R-mRNA reactive cells were observed throughout the inner nuclear layer. Morphologically, labelled cells resemble amacrines and bipolars but not horizontal cells. Reactivity with splice variant-specific oligonucleotide probes suggested that the D2LR variant is the predominant if not the only D2R isoform in the rat retina. D2R-mRNA reactivity was not observed in other retinal layers, in particular not in photoreceptor inner segments, which displayed D4R-mRNA reactivity. D3R-mRNA reactivity was not detected. The results indicate that D2-like responses are mediated through the D2R subtype, by an autoreceptor mechanism in dopaminergic cells, and by volume transmission in non-dopaminergic cells of the inner retina. D2-like responses in photoreceptors probably represent D4R activation.

Animals↗
PubMed1998

Glutamine synthetase activity in patients with Parkinson's disease.

According to current concepts, the excitatory amino acid glutamate is involved in the pathogenesis of Parkinson's disease (PD). Overactivity of glutamatergic projection neurons and beneficial effect of antiglutamatergic substances in animal experiments suggest that excess supply of glutamate might contribute to the pathophysiology of PD. Reduced activity of the glutamate metabolizing enzyme glutamine synthetase (GS) leads to decreased uptake of glutamate and thus abundant glutamate. Here we report that PD patients and age-matched controls are comparable with respect to GS activity in peripheral blood mononuclear cells (PBMC). These results imply no systemic dysregulation of the enzyme GS in patients with PD.

Case-Control Studies↗
PubMed1996

Identified glial cells in the early postnatal mouse hippocampus display different types of Ca2+ currents.

Based on their typical pattern of membrane currents, four populations of glial cells could be identified in thin brain slices of the postnatal hippocampus. In the present study, we applied the patch-clamp technique to glial cells in the hippocampal CA1 region, which are characterized by a complex pattern of different Na+ and K+ currents ("complex" cells). These cells were identified as non-neuronal cells, most likely astrocytes, by their glutamine synthetase immunoreactivity. Two types of glial Ca2+ currents could be identified that differed in their kinetics and pharmacological properties. A low-voltage activated (LVA), fast inactivating component was activated at membrane potentials positive to -60 mV and reached maximum current amplitudes at about -20 mV. This current was sensitive to amiloride and thus displayed properties of neuronal LVA currents. The threshold potential of the second Ca2+ current component was at about -40 mV, and peak currents were observed at 0 mV. In contrast to the LVA component, the inactivation of these high-voltage activated (HVA) currents slowed down with increasing depolarizations. This current was sensitive to low concentrations of Cd2+ but was not affected by amiloride. A small fraction of the HVA currents was sensitive to nifedipine, and omega-conotoxin GVIA (omega-CgTx) was also found to reduce the glial HVA component. The study provides electrophysiological and pharmacological characterization of different types of Ca2+ currents in gray matter glial cells in situ.

Animals↗
PubMed1996

Possible role of the Müller cell in uptake and metabolism of glutamate in the mammalian outer retina.

It is not known how glutamate released synaptically in the outer plexiform layer of the retina is inactivated. Since there is no extracellular enzymatic degradation, glutamate released from photoreceptors is taken up intracellularly by at least one of the three transporters known, and metabolized by a glutamate degrading enzyme. In order to elucidate which of the transporters and enzymes are involved in this process, immuno-electron microscopy was carried out on retinal sections of adult albino rats, applying antiserum against either glutamine synthetase (GS) or L-glutamate-L-aspartate transporter (GLAST). Both stainings revealed immunoreactivity in Müller cells and particularly in their processes tightly ensheathing rod photoreceptor terminals. Thus, although this remains to be tested functionally, transmitter uptake and subsequent degradation at photoreceptor terminals might be preferentially controlled by GLAST and GS expressed in the fine Müller cell processes.

Amino Acid Transport System X-AG↗
PubMed1996

Spatial relationship of lectin-labelled extracellular matrix and glutamine synthetase-immunoreactive astrocytes in rat cortical forebrain regions.

Extracellular matrix proteoglycans have previously been revealed by immunocytochemical and lectin-histochemical methods as distinct perineuronal nets in the microenvironment of different types of neurons, but also as a diffuse stain throughout the neuropil in region-dependent patterns. Ultrastructural investigations of perineuronal nets in subcortical regions have demonstrated glycan components in the close vicinity of astrocyte processes, suggesting that the extracellular matrix contributes differentially to the glianeuron interface. In the present study the spatial relationship of extracellular matrix components and astrocytes was characterised at the regional and cellular level by lectin histochemistry (soybean agglutinin, Vicia villosa agglutinin, Wisteria floribunda agglutinin) and antiglutamine synthetase immunocytochemistry in the rat neocortex and hippocampus. In most cortical areas layer-specific patterns of diffuse neuropil staining revealed by the lectins could also be recognised after glutamine synthetase (GS) immunostaining. In double-labelling experiments GS-immunoreactive astrocyte processes were found to reach lectin-stained perineuronal nets. GS-immunoreactivity was often parallelled but did not coincide with the lectin label completely, but was observed to form net-like structures similar to the perineuronal lectin staining. Using immunocytochemistry with anti-GS perineuronal, net-like structures were demonstrated on certain parvalbumin-immunopositive neurons which are known to be ensheathed by lectin-stained perineuronal nets. It was evident that a single neuron may receive net-like contacts from several astrocytes and that a single astrocyte can contribute to perineuronal nets on more than one neuron. The findings support the view that N-acetylgalactosamine-containing extracellular matrix molecules and astrocytic processes are topically associated to a high degree. Different proportions of both components may specify the individual neuronal micro-environment.

Acetylgalactosamine↗
PubMed1995

Coincidence of L-glutamate/L-aspartate transporter (GLAST) and glutamine synthetase (GS) immunoreactions in retinal glia: evidence for coupling of GLAST and GS in transmitter clearance.

Our aim was to identify proteins that mediate the uptake and degradation of synaptically released glutamate, focusing on the rat retina with its well-defined glutamatergic pathways. Immunoreactivity against the L-glutamate/L-aspartate transporter (GLAST) is present in Müller cells. Ultrastructurally, even the finest glial processes, particularly those ensheathing identified structures of glutamatergic transmission (rod spherules), are immunoreactive for GLAST. Further light and electron microscopic observations revealed that also retinal astrocytes and pigment epithelial cells are immunoreactive for GLAST. No neuronal or microglial staining was observed. This is in line with uptake of exogenous [3H]glutamate previously localized specifically in Müller cells and pigment epithelium (Ehinger and Falck: Brain Res 33:157-172, 1971). Since endogenous glutamate can only be demonstrated in Müller cells if glutamine synthetase (GS) is inhibited (Pow and Robinson: Neuroscience 60:355-366, 1994), the immunocytochemical localization of GS was determined. GS immunoreactivity was found in all but only those cell types immunoreactive for GLAST. The light and electron microscopic patterns of immunoreactivity were very similar, particularly in the outer plexiform layer. The three cell types containing both GS and GLAST (Müller cells, astrocytes, and retinal pigment epithelium) are related developmentally. In the light of the two references quoted the present data indicate that the proteins mediating retinal uptake and degradation of synaptically released glutamate may be GLAST and GS, respectively, and that they may operate in concert to terminate the neurotransmitter action of glutamate.

Amino Acid Transport System X-AG↗