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Shimon Ben-Shabat

Bio: Shimon Ben-Shabat is an academic researcher from Ben-Gurion University of the Negev. The author has contributed to research in topics: Prodrug & Targeted drug delivery. The author has an hindex of 27, co-authored 69 publications receiving 6060 citations. Previous affiliations of Shimon Ben-Shabat include Columbia University & Hebrew University of Jerusalem.


Papers
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Journal ArticleDOI
TL;DR: Upon intravenous administration to mice, 2-Ara-Gl caused the typical tetrad of effects produced by THC: antinociception, immobility, reduction of spontaneous activity, and lowering of the rectal temperature.

2,764 citations

Journal ArticleDOI
04 Oct 2001-Nature
TL;DR: It is shown that, after injury to the mouse brain, 2-AG may have a neuroprotective role in which the cannabinoid system is involved and this effect was dose-dependently attenuated by SR-141761A, an antagonist of the CB1 cannabinoid receptor.
Abstract: Traumatic brain injury triggers the accumulation of harmful mediators that may lead to secondary damage. Protective mechanisms to attenuate damage are also set in motion. 2-Arachidonoyl glycerol (2-AG) is an endogenous cannabinoid, identified both in the periphery and in the brain, but its physiological roles have been only partially clarified. Here we show that, after injury to the mouse brain, 2-AG may have a neuroprotective role in which the cannabinoid system is involved. After closed head injury (CHI) in mice, the level of endogenous 2-AG was significantly elevated. We administered synthetic 2-AG to mice after CHI and found significant reduction of brain oedema, better clinical recovery, reduced infarct volume and reduced hippocampal cell death compared with controls. When 2-AG was administered together with additional inactive 2-acyl-glycerols that are normally present in the brain, functional recovery was significantly enhanced. The beneficial effect of 2-AG was dose-dependently attenuated by SR-141761A, an antagonist of the CB1 cannabinoid receptor.

708 citations

Journal ArticleDOI
TL;DR: The data indicate that the biological activity of 2-Ara-Gl can be increased by related, endogenous 2-acyl-glycerols, which alone show no significant activity in any of the tests employed, suggesting that this effect ('entourage effect') may represent a novel route for molecular regulation of endogenous cannabinoid activity.

540 citations

Journal Article
TL;DR: The augmentation of cell death in the presence of D(2)O and the protection afforded by quenchers and scavengers of singlet oxygen, indicates that the generation of Singlet oxygen may be involved in the mechanisms leading to the death of A2E-containing RPE cells after blue light illumination.
Abstract: Purpose The lipofuscin fluorophore A2E is known to be an initiator of blue-light-induced apoptosis in retinal pigment epithelial cells (RPE) The purpose of this study was to evaluate the role of oxidative mechanisms in mediating the cellular damage Methods Human RPE (ARPE-19) cells that had accumulated A2E were exposed to blue light in the presence and absence of oxygen, and nonviable cells were quantified Potential suppressors (histidine, azide, 1,4-diazabicyclooctane [DABCO], and 1,3-dimethyl-2-thiourea [DMTU]) and enhancers (deuterium oxide [D(2)O] and 3-aminotriazole [3-AT]) of oxidative damage, were also screened for their ability to modulate the frequency of nonviable cells A2E in PBS, with and without an oxygen-depleter or singlet-oxygen quencher and A2E-laden RPE, were exposed to 430-nm light and examined by reversed-phase high performance liquid chromatography (HPLC) and fast atom bombardment mass spectrometry (FAB-MS) Results The death of blue-light-illuminated A2E-laden RPE was blocked in oxygen-depleted media When A2E-laden RPE were transferred to D(2)O-based media and then irradiated (480 nm), the number of nonviable cells was increased, whereas the latter was decreased in the presence of histidine, DABCO, and azide Conversely, no affect was observed with 3-AT and DMTU When A2E, in either acellular or cellular environments, was irradiated at 430 nm, FAB-MS revealed the generation of a series of higher molecular mass derivatives of A2E The sizes of these species increased by increments of mass 16 The generation of these photo-products was accompanied by the consumption of A2E, the latter being diminished, however, when illumination was performed after oxygen depletion and in the presence of a singlet-oxygen quencher Conclusions The augmentation of cell death in the presence of D(2)O and the protection afforded by quenchers and scavengers of singlet oxygen, indicates that the generation of singlet oxygen may be involved in the mechanisms leading to the death of A2E-containing RPE cells after blue light illumination The finding that irradiation also produces oxygen-dependent photochemical changes in A2E, indicates that the effects of singlet oxygen may be mediated either directly or through the generation of reactive photo-products of A2E

289 citations

Journal ArticleDOI
TL;DR: In reaction mixtures of retinal and outer segments and in samples of Royal College of Surgeons rat retina containing outer segment membranous debris, A2-PE was detected as a series of high performance liquid chromatography peaks, each with UV similar to reference A1-PE, thus confirming A2 -PE as the A2E precursor.

242 citations


Cited by
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Journal ArticleDOI
TL;DR: Substantial insight is provided into the intricate mechanisms of bacterial regulation of the cross-talk between the host and gut microbiota and provides a rationale for the development of a treatment that uses this human mucus colonizer for the prevention or treatment of obesity and its associated metabolic disorders.
Abstract: Obesity and type 2 diabetes are characterized by altered gut microbiota, inflammation, and gut barrier disruption. Microbial composition and the mechanisms of interaction with the host that affect gut barrier function during obesity and type 2 diabetes have not been elucidated. We recently isolated Akkermansia muciniphila, which is a mucin-degrading bacterium that resides in the mucus layer. The presence of this bacterium inversely correlates with body weight in rodents and humans. However, the precise physiological roles played by this bacterium during obesity and metabolic disorders are unknown. This study demonstrated that the abundance of A. muciniphila decreased in obese and type 2 diabetic mice. We also observed that prebiotic feeding normalized A. muciniphila abundance, which correlated with an improved metabolic profile. In addition, we demonstrated that A. muciniphila treatment reversed high-fat diet-induced metabolic disorders, including fat-mass gain, metabolic endotoxemia, adipose tissue inflammation, and insulin resistance. A. muciniphila administration increased the intestinal levels of endocannabinoids that control inflammation, the gut barrier, and gut peptide secretion. Finally, we demonstrated that all these effects required viable A. muciniphila because treatment with heat-killed cells did not improve the metabolic profile or the mucus layer thickness. In summary, this study provides substantial insight into the intricate mechanisms of bacterial (i.e., A. muciniphila) regulation of the cross-talk between the host and gut microbiota. These results also provide a rationale for the development of a treatment that uses this human mucus colonizer for the prevention or treatment of obesity and its associated metabolic disorders.

3,263 citations

Journal ArticleDOI
TL;DR: These factors have been shown to substantially affect the biodistribution and blood circulation half-life of circulating nanoparticles by reducing the level of nonspecific uptake, delaying opsonization, and increasing the extent of tissue specific accumulation.
Abstract: Nanoparticle (NP) drug delivery systems (5−250 nm) have the potential to improve current disease therapies because of their ability to overcome multiple biological barriers and releasing a therapeutic load in the optimal dosage range. Rapid clearance of circulating nanoparticles during systemic delivery is a critical issue for these systems and has made it necessary to understand the factors affecting particle biodistribution and blood circulation half-life. In this review, we discuss the factors which can influence nanoparticle blood residence time and organ specific accumulation. These factors include interactions with biological barriers and tunable nanoparticle parameters, such as composition, size, core properties, surface modifications (pegylation and surface charge), and finally, targeting ligand functionalization. All these factors have been shown to substantially affect the biodistribution and blood circulation half-life of circulating nanoparticles by reducing the level of nonspecific uptake, de...

3,009 citations

Journal ArticleDOI
TL;DR: It is considered premature to rename cannabinoid receptors after an endogenous agonist as is recommended by the International Union of Pharmacology Committee on Receptor Nomenclature and Drug Classification, because pharmacological evidence for the existence of additional types of cannabinoid receptor is emerging and other kinds of supporting evidence are still lacking.
Abstract: Two types of cannabinoid receptor have been discovered so far, CB(1) (2.1: CBD:1:CB1:), cloned in 1990, and CB(2) (2.1:CBD:2:CB2:), cloned in 1993. Distinction between these receptors is based on differences in their predicted amino acid sequence, signaling mechanisms, tissue distribution, and sensitivity to certain potent agonists and antagonists that show marked selectivity for one or the other receptor type. Cannabinoid receptors CB(1) and CB(2) exhibit 48% amino acid sequence identity. Both receptor types are coupled through G proteins to adenylyl cyclase and mitogen-activated protein kinase. CB(1) receptors are also coupled through G proteins to several types of calcium and potassium channels. These receptors exist primarily on central and peripheral neurons, one of their functions being to inhibit neurotransmitter release. Indeed, endogenous CB(1) agonists probably serve as retrograde synaptic messengers. CB(2) receptors are present mainly on immune cells. Such cells also express CB(1) receptors, albeit to a lesser extent, with both receptor types exerting a broad spectrum of immune effects that includes modulation of cytokine release. Of several endogenous agonists for cannabinoid receptors identified thus far, the most notable are arachidonoylethanolamide, 2-arachidonoylglycerol, and 2-arachidonylglyceryl ether. It is unclear whether these eicosanoid molecules are the only, or primary, endogenous agonists. Hence, we consider it premature to rename cannabinoid receptors after an endogenous agonist as is recommended by the International Union of Pharmacology Committee on Receptor Nomenclature and Drug Classification. Although pharmacological evidence for the existence of additional types of cannabinoid receptor is emerging, other kinds of supporting evidence are still lacking.

2,619 citations

Journal Article
TL;DR: In this article, the authors discuss the factors which can influence nanoparticle blood residence time and organ specific accumulation, including interactions with biological barriers and tunable nanoparticle parameters, such as composition, size, core properties, surface modifications (pegylation and surface charge), and targeting ligand functionalization.
Abstract: Nanoparticle (NP) drug delivery systems (5−250 nm) have the potential to improve current disease therapies because of their ability to overcome multiple biological barriers and releasing a therapeutic load in the optimal dosage range. Rapid clearance of circulating nanoparticles during systemic delivery is a critical issue for these systems and has made it necessary to understand the factors affecting particle biodistribution and blood circulation half-life. In this review, we discuss the factors which can influence nanoparticle blood residence time and organ specific accumulation. These factors include interactions with biological barriers and tunable nanoparticle parameters, such as composition, size, core properties, surface modifications (pegylation and surface charge), and finally, targeting ligand functionalization. All these factors have been shown to substantially affect the biodistribution and blood circulation half-life of circulating nanoparticles by reducing the level of nonspecific uptake, de...

2,543 citations

Journal ArticleDOI
TL;DR: This review summarizes the current knowledge of RPE functions and describes how failure of these functions causes loss of visual function.
Abstract: Located between vessels of the choriocapillaris and light-sensitive outer segments of the photoreceptors, the retinal pigment epithelium (RPE) closely interacts with photoreceptors in the maintenance of visual function. Increasing knowledge of the multiple functions performed by the RPE improved the understanding of many diseases leading to blindness. This review summarizes the current knowledge of RPE functions and describes how failure of these functions causes loss of visual function. Mutations in genes that are expressed in the RPE can lead to photoreceptor degeneration. On the other hand, mutations in genes expressed in photoreceptors can lead to degenerations of the RPE. Thus both tissues can be regarded as a functional unit where both interacting partners depend on each other.

2,387 citations