Non-destructive comparative evaluation of fossil amber using terahertz time-domain spectroscopy.

Fossilized plant resins, or ambers, offer a unique paleontological window into the history of life. A natural polymer, amber can preserve aspects of ancient environments, including whole organisms, for tens or even hundreds of millions of years. While most amber research involves imaging with visual light, other spectra are increasingly used to characterize both organismal inclusions as well as amber matrix.

Metabolic studies of synaptamide in an immortalized dopaminergic cell line.

Introduction: Synaptamide, the N-acylethanolamine of docosahexaenoic acid (DHA), is structurally similar to the endocannabinoid N-arachidonoylethanolamine, anandamide. It is an endogenous ligand at the orphan G-protein coupled receptor 110 (GPR110; ADGRF1), and induces neuritogenesis and synaptogenesis in hippocampal and cortical neurons, as well as neuronal differentiation in neural stem cells.

Purpose: Our goal was to characterize the metabolic fate (synthesis and metabolism) of synaptamide in a dopaminergic cell line using immortalized fetal mesencephalic cells (N27 cells).

N-Docosahexaenoylethanolamine (synaptamide): Carbon-14 radiolabeling and metabolic studies.

N-Docosahexaenoylethanolamine (synaptamide) is structurally similar to the endocannabinoid N-arachidonoylethanolamine (anandamide), but incorporates the omega-3 22:6 fatty acid docosahexaenoic acid (DHA) in place of the omega-6 20:4 fatty acid arachidonic acid (AA). Some brain membrane lipid effects may be mediated via synaptamide. In competition experiments with mouse brain homogenate in vitro, we found that synaptamide was an order-of-magnitude poorer inhibitor of radioactive anandamide hydrolysis than was anandamide itself.

Brain uptake and metabolism of the endocannabinoid anandamide labeled in either the arachidonoyl or ethanolamine moiety.

Introduction: Anandamide (N-arachidonoylethanolamine) is a retrograde neuromodulator that activates cannabinoid receptors. The concentration of anandamide in the brain is controlled by fatty acid amide hydrolase (FAAH), which has been the focus of recent drug discovery efforts. Previous studies in C57BL/6 mice using [H-arachidonoyl]anandamide demonstrated deposition of tritium in thalamus and cortical areas that was blocked by treatment with an FAAH inhibitor and that was not seen in FAAH-knockout mice.

Tolerance to the Diuretic Effects of Cannabinoids and Cross-Tolerance to a κ-Opioid Agonist in THC-Treated Mice.

Daily treatment with cannabinoids results in tolerance to many, but not all, of their behavioral and physiologic effects. The present studies investigated the effects of 7-day exposure to 10 mg/kg daily of Δ(9)-tetrahydrocannabinol (THC) on the diuretic and antinociceptive effects of THC and the synthetic cannabinoid AM4054. Comparison studies determined diuretic responses to the κ-opioid agonist U50,488 and furosemide.

Integrity of (111)In-radiolabeled superparamagnetic iron oxide nanoparticles in the mouse.

Introduction: Iron-oxide nanoparticles can act as contrast agents in magnetic resonance imaging (MRI), while radiolabeling the same platform with nuclear medicine isotopes allows imaging with positron emission tomography (PET) or single-photon emission computed tomography (SPECT), modalities that offer better quantification. For successful translation of these multifunctional imaging platforms to clinical use, it is imperative to evaluate the degree to which the association between radioactive label and iron oxide core remains intact in vivo.

Methods: We prepared iron oxide nanoparticles stabilized by oleic acid and phospholipids which were further radiolabeled with (59)Fe, (14)C-oleic acid, and (111)In.

Synthesis and preliminary evaluation of N-(16-18F-fluorohexadecanoyl)ethanolamine (18F-FHEA) as a PET probe of N-acylethanolamine metabolism in mouse brain.

N-Acylethanolamines are lipid signaling molecules found throughout the plant and animal kingdoms. The best-known mammalian compound of this class is anandamide, N-arachidonoylethanolamine, one of the endogenous ligands of cannabinoid CB1 and CB2 receptors. Signaling by N-acylethanolamines is terminated by release of the ethanolamine moiety by hydrolyzing enzymes such as fatty acid amide hydrolase (FAAH) and N-acylethanolamine-hydrolyzing amidase (NAAA).

Assay and inhibition of diacylglycerol lipase activity.

A series of N-formyl-α-amino acid esters of β-lactone derivatives structurally related to tetrahydrolipstatin (THL) and O-3841 were synthesized that inhibit human and murine diacylglycerol lipase (DAGL) activities. New ether lipid reporter compounds were developed for an in vitro assay to efficiently screen inhibitors of 1,2-diacyl-sn-glycerol hydrolysis and related lipase activities using fluorescence resonance energy transfer (FRET). A standardized thin layer chromatography (TLC) radioassay of diacylglycerol lipase activity utilizing the labeled endogenous substrate [1″-(14)C]1-stearoyl-2-arachidonoyl-sn-glycerol with phosphorimaging detection was used to quantify inhibition by following formation of the initial product [1″-(14)C]2-arachidonoylglycerol and further hydrolysis under the assay conditions to [1-(14)C]arachidonic acid.

A methodology for radiolabeling of the endocannabinoid 2-arachidonoylglycerol (2-AG).

The metabolic intermediate and endocannabinoid signaling lipid 2-arachidonoylglycerol (2-AG) has not been readily labeled, primarily because of its instability toward rearrangement. We now detail a synthetic method that easily gives tritiated 2-AG from [5,6,8,9,11,12,14,15-(3)H(N)]arachidonic acid in two steps. We utilized a short chain 1,3-diacylglycerol and proceeded through the "structured lipid" [5'',6'',8'',9'',11'',12'',14'',15''-(3)H(N)]2-arachidonoyl-1,3-dibutyrylglycerol, a triacylglycerol that was conveniently deprotected in ethanol with acrylic beads containing Candida antarctica lipase B to give [5'',6'',8'',9'',11'',12'',14'',15''-(3)H(N)]2-arachidonoylglycerol ([(3)H]2-AG).

Requirements, in terms of root canal treatment, of undergraduates in the European Union: an audit of teaching practice.

Aim: The purpose of this study was to gather information from across the EU about requirements of dental undergraduates in the area of root canal treatment (RCT).

Methodology: One hundred and ninety-two EU dental schools were invited to complete an online survey. The survey inquired about assessment in RCT, whether students complete a minimum number of RCTs, whether this includes both anterior and posterior teeth, and if root canal retreatment and endodontic surgery are compulsory.

The preparation of 2-O-[1'-C]arachidonoyl-1-O-stearoyl-sn-glycerol.

2-O-Arachidonoyl-1-O-stearoyl-sn-glycerol is the most abundant molecular species of the 1,2-diacyl-sn-glycerol signaling lipids in neural tissue. The facile preparation of 2-O-[1'-(14)C]arachidonoyl-1-O-stearoyl-sn-glycerol from 2-O-[1'-(14)C]arachidonoyl-1-O-stearoyl-sn-glycero-3-phosphocholine at a hexane and phosphate buffer interface with phospholipase C was demonstrated on a 20 µCi scale in 83% radiochemical yield. The specific activity of the product 2-O-[1'-(14)C]arachidonoyl-1-O-stearoyl-sn-glycerol was 57.

Long-term effects of irradiation with iron-56 particles on the nigrostriatal dopamine system.

Exposure to heavy ions during a Mars mission might damage the brain, thus compromising mission success and the quality of life of returning astronauts. Several workers have suggested that the dopamine system is particularly sensitive to heavy ion radiation, but direct evidence for this notion is lacking. We examined measures of brain dopamine viability at times up to 15 months after acute exposure of rats to (56)Fe (1.

Biodistribution of radiolabeled ethanol in rodents.

The biodistribution of [1-(14)C]ethanol in rodents was examined to determine sites of concentration of ethanol or its metabolites that may contribute to its toxicological and pharmacokinetic characteristics. After i.v.

Applications of Clinical Dopamine Imaging.

Recent technologic advances make it increasingly possible to image neurotransmitter systems in living human brain. The dopamine system has been most intensively studied owing to its involvement in several brain disorders, including motor disorders such as Parkinson's disease and Huntington's disease, as well as psychiatric disorders such as schizophrenia, depression, and compulsive behavioral disorders of multiple types. A variety of aspects of dopamine receptor density, function, and dopaminergic terminal status can now be assessed using the minimally invasive neuroimaging techniques of positron emission tomography and single-photon emission computed tomography.

Applications of clinical dopamine imaging.

Recent technologic advances make it increasingly possible to image neurotransmitter systems in living human brain, The dopamine system has been most intensively studied owing to its involvement in several brain disorders such as Parkinson's disease and Huntington's disease, as well as psychiatric disorders such as schizophrenia, depression, and compulsive behavioral disorders of multiple types. A variety of aspects of dopamine receptor density, function, and dopaminergic terminal status can now be assessed using the minimally invasive neuroimaging techniques of positron emission tomography and single-photon emission computed tomography. Although these techniques are currently used most often in the context of research, clinical applications are rapidly emerging.

MicroPET investigation of chronic long-term neurotoxicity from heavy ion irradiation.

Positron emission tomography (PET) permits imaging of the regional biodistribution and pharmacokinetics of compounds labeled with short-lived positron-emitting isotopes. It has enabled evaluation of neurochemical systems in the living human brain, including effects of toxic substances. MicroPET devices allow studies of the rat brain with a spatial resolution of approximately 2 mm.

Evaluation of the in vivo receptor occupancy for the behavioral effects of cannabinoids using a radiolabeled cannabinoid receptor agonist, R-[125/131I]AM2233.

G-protein coupled receptors exist in both high and low agonist affinity conformations, with tracer levels of agonist radioligands preferentially binding to the former. The goal of the present study was to characterize the in vivo binding of the aminoalkyindole-based, CB1 receptor agonist, R-[125/131I]AM2233 ((2-[125/131I]iodo-phenyl)-[1-(1-methyl-piperidin-2-yl-methyl)-1H-indol-3-yl]-methanone), and to use this radiotracer to selectively measure the receptor occupancy by the related CB1 receptor agonist, WIN55212-2, to the agonist-preferring affinity state of the receptor. In mouse locomotor assays, both WIN55212-2 and AM2233 (racemic) produced an approximately 60% reduction in activity at 1 mg/kg, (i.

Imaging of the brain cannabinoid system.

This review covers two major strategies for imaging of the brain cannabinoid system: autoradiography and in vivo neuroimaging. Cannabinoid receptors can be imaged directly with autoradiography in brain slices using radiolabeled cannabinoid receptor ligands. In addition, the effects of pharmacologic doses of unlabeled cannabinoid drugs can be autoradiographically imaged using indicators of blood flow or indicators of metabolism such as glucose analogs.

Ex vivo imaging of fatty acid amide hydrolase activity and its inhibition in the mouse brain.

There is recent behavioral evidence that fatty acid amide hydrolase (FAAH) inhibitors produce a subset of cannabinoid receptor agonist effects, suggesting both anandamide-specific behavioral functions and possible regional differences in FAAH inhibitory effects. Here, we introduce a novel imaging method to quantify regional differences in brain FAAH activity. Upon intravenous [3H]anandamide administration, brain FAAH activity generates [3H]arachidonic acid, which is promptly trapped in membrane phospholipids.

PET imaging in clinical drug abuse research.

Over the last two decades, SPECT (single photon emission computed tomography) and especially PET (positron emission tomography) have proven increasingly effective imaging modalities in the study of human psychopharmacology. Abusing populations can be studied at multiple times after abstinence begins, to give information about neurochemical and physiological adaptations of the brain during recovery from addiction. Individual human subjects can be studied using multiple positron labeled radiotracers, so as to probe more than one facet of brain function.

Potent cannabinergic indole analogues as radioiodinatable brain imaging agents for the CB1 cannabinoid receptor.

A series of novel aminoalkylindoles was synthesized in an effort to develop compounds that are potent agonists at the CB1 cannabinoid receptor and that are also easily labeled with radioisotopes of iodine for biochemical and imaging studies. 2-Iodophenyl-[1-(1-methylpiperidin-2-ylmethyl)-1H-indol-3-yl]methanone (8, AM2233) had a very high affinity for the rat CB1 receptor, with most of the affinity residing with the (R)-enantiomer. Radioiodinated 8, (R)-8, and (S)-8 were prepared by radioiododestannylation of the tributyltin analogues in high yields, radiochemical purities, and specific radioactivities.

Low doses of alcohol substantially decrease glucose metabolism in the human brain.

Moderate doses of alcohol decrease glucose metabolism in the human brain, which has been interpreted to reflect alcohol-induced decreases in brain activity. Here, we measure the effects of two relatively low doses of alcohol (0.25 g/kg and 0.

Candidate PET radioligands for cannabinoid CB1 receptors: [18F]AM5144 and related pyrazole compounds.

Introduction: The mammalian brain contains abundant G protein-coupled cannabinoid CB(1) receptors that respond to Delta(9)-tetrahydrocannabinol, the active ingredient of cannabis. The availability of a positron emission tomography (PET) radioligand would facilitate studies of the addictive and medicinal properties of compounds that bind to this receptor. Among the known classes of ligands for CB(1) receptors, the pyrazoles are attractive targets for radiopharmaceutical development because they are antagonists and are generally less lipophilic than the other classes.

Brain kinetics of methylphenidate (Ritalin) enantiomers after oral administration.

Methylphenidate (MP) (Ritalin) is widely used for the treatment of attention deficit hyperactivity disorder (ADHD). It is a chiral drug, marketed as the racemic mixture of d- and l-threo enantiomers. Our previous studies (PET and microdialysis) in humans, baboons, and rats confirm the notion that pharmacological specificity of MP resides predominantly in the d-isomer.