Methods for Labeling Nonphagocytic Cells with MR Contrast Agents
Michel M. J. Modo, Jeff W. M. Bulte in Molecular and Cellular MR Imaging, 2007
Liposomal “artificial virus-like envelopes” have been used to label cells and showed enhanced T1 relaxivity with degradation of the envelope.64 GdDOTA covalently attached to D-Tat facilitated, via macropinocytosis, the entry of the agent into leukemia cells and demonstrated T1 contrast enhancement at 4.7 tesla.65 By targeting the amino acid active transport in cancer, Lattuada et al.66 developed gadolinium complexes conjugated to agmatine, arginine, and glutamine and labeled tumor cells in culture. In this study, glutamine (gln)–GdDTPA-labeled rat hepatocellular carcinoma cell pellets had a greater than 50% decrease in T1 than unlabeled control cells at 7 tesla. Comparison of membrane-bound to internalized forms of the contrast agent was made and demonstrated a moderate reduction of T1 when the gadolinium chelate was internalized in the hepatocellular carcinoma cell, compared to bound to its surface.
Biogenic Amines in Plant Food
Akula Ramakrishna, Victoria V. Roshchina in Neurotransmitters in Plants, 2018
Fermented beverages such as boza (a traditional cereal-based fermented Turkish beverage), beer, cider (an alcoholic beverage made from apple juice), and wine contain histamine and other biogenic amines (Stratton et al., 1991; Ercan et al., 2013). Fermented beverages represent an important category of foodstuff that can supply significant quantities of biogenic amines. Wine is the most frequently fermented alcoholic beverage. Since alcohol is an inhibitor of monoamine oxidases (MAOs), the control of biogenic amines in fermented beverages is of considerable importance for consumer’s health (Russo et al., 2010; Ercan et al., 2013). Agmatine, cadaverine, ethanolamine, histamine, putrescine, and tyramine are formed at larger concentrations during fermentation of alcohol (Santos, 1996). In wine biogenic amine may have two various sources, raw materials and fermentation processes (Spano et al., 2010).
Micronutrients in the Prevention and Improvement of the Standard Therapy for Alzheimer’s Disease
Kedar N. Prasad in Micronutrients in Health and Disease, 2019
The activation of Nrf2 becomes unresponsive to ROS during chronic oxidative stress found in AD. The levels of Nrf2 decreased in the hippocampal neurons from patients with AD and Lewy body variant of AD compared to normal hippocampal neurons.336 Treatment with tert-butylhydroquinone, an inducer of Nrf2, or with adenoviral Nrf2 gene transfer, protected neurons against Aβ-induced toxicity in transgenic mouse model of AD.364 Other agents that induce Nrf2 include Pierisformoside B (PFB) (isolated from Rhododendron brachycarpum)365 and Cudraflavone B, a prenylated flavone, isolated from Cudrania triscuspidata.366 Agmatine treatment inhibited the accumulation of beta-amyloids, and enhanced insulin signal transduction, and improved cognitive function via the Nrf2/ARE pathway in streptomycin-induced AD rat model.367 These inducers of Nrf2 reduced markers of oxidative damage and chronic inflammation in the hippocampal neurons.
Ketogenic diet: overview, types, and possible anti-seizure mechanisms
Published in Nutritional Neuroscience, 2021
Mohammad Barzegar, Mohammadreza Afghan, Vahid Tarmahi, Meysam Behtari, Soroor Rahimi Khamaneh, Sina Raeisi
Agmatine is a metabolite derived from L-arginine through arginine decarboxylation. This small molecule is found throughout the brain, mainly in the hippocampus. Agmatine has also been partially found in synapses and can be considered as an inhibitory neurotransmitter. It may exert anticonvulsant effects probably by inhibiting different brain excitatory receptors including N-methyl-D-aspartate (NMDA), adrenaline, and histamine receptors. It has been shown in a study by Calderón et al. that KD could increase in the hippocampus agmatine levels of the studied rats [49]. This study could support the notion that KD-induced enhancement in the brain levels of agmatine which has neuroprotection effects can be considered as another anti-seizure mechanism of this therapeutic diet.
Protective effect against brain tissues oxidative damage as a possible mechanism for beneficial effects of L -arginine on lipopolysaccharide induced memory impairment in rats
Published in Drug and Chemical Toxicology, 2018
Mahmoud Hosseini, Akbar Anaeigoudari, Farimah Beheshti, Mohammad Soukhtanloo, Reza Nosratabadi
On the other hand, LA can be converted to agmatine through decarboxylation by mitochondrial arginine decarboxylase enzyme (Molderings and Haenisch 2012). Agmatine has been proposed to act as a competitive inhibitor for nNOS and iNOS (Auguet et al. 1995) as well as it can inhibit endothelial NOS (eNOS) (Galea et al. 1996). Because of co-storing with L-glutamate in hippocampal neurons, agmatine may also act as a neuromodulator via blocking the N-methyl-D-aspartate (NMDA) receptors and inhibiting nNOS in the hippocampus of rats (Aricioglu-Kartal and Uzbay 1997). Interestingly, other researchers have pointed that agmatine reversed spatial learning and memory impairment caused by LPS in rats (Zarifkar et al. 2010). Additionally, it has been reported that LA-derived agmatine has a neuro-protective role against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) neurotoxicity and spinal cord ischemia and prevents from development of AD (Chu et al. 1995, Gilad et al. 2005). In this study the level of NO metabolites in hippocampus tissues decreased in LA-LPS group vis-à-vis LPS group. Therefore, it is thought that a part of the improving effect of LA on memory impairment may be mediated through inhibition of NOS or NMDA receptors or both of them by LA-derived agmatine; however, it needs to be more investigated.
Evaluation of plasma agmatine level and its metabolic pathway in patients with bipolar disorder during manic episode and remission period
Published in International Journal of Psychiatry in Clinical Practice, 2019
Emine Yılmaz, M. Ramazan Şekeroğlu, Ekrem Yılmaz, Erdem Çokluk
The opinion about the anti-stress effect of agmatine was first proposed by Streward and Mc Kay (2000). Experimental animal studies conducted by Aricioglu and Altunbas (2003) have indicated that endogenous agmatine production elevated more than five-fold of normal levels under stress, systemic agmatine had an anxiolytic potential even in low doses, agmatine which is an endogenous substance elevated for preventing the brain against stress. Experimental animal studies have also indicated that agmatine administered to rats via intra-peritoneal (0.01–50 mg/kg) or intra-cranial vein could have anti-depressant effect alone and also enhance the anti-depressant effect of imipramine (Zomkowski et al., 2002). Aricioglu and Altunbas (2003) have reported that the effect of agmatine is not dose-dependent.
Related Knowledge Centers
- Agmatinase
- Amine
- Guanidine
- Polyamine
- Putrescine
- Urea
- Urea Cycle
- Nitric Oxide
- Arginine
- Foodborne Illness