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Topic Review
Arsenic metabolism, excretion, and toxicity
       Arsenic is a global, naturally present pollutant found in drinking water that is consumed by millions of people throughout the world. Humans have evolved an arsenic methyltransferase present in high levels in the liver to expedite its excretion from the body. Most organisms have this enzyme. The enzyme generates monomethyl (MMA) and dimethyl arsenic (DMA). These methylated species are considered more toxic than arsenite, but they bind less tightly to proteins and thereby are excreted more rapidly from the body. Individuals who have been chronically exposed to arsenite were found to possess advantageous genotypes to metabolize arsenites. However, higher expression of AS3MT was found to yield more toxic MMA but lower amounts were still capable of metabolizing arsenite to DMA. This likely reflects the complex metabolic processes involving not only AS3MT, but antioxidants and upstream regulators of AS3MT, potentially transcription factor NRF2. This article discusses arsenic metabolism, excretion, toxicity, and the evolution of this enzyme across various species. The fact that so many organisms have evolved to possess this arsenite metabolizing enzyme is indicative of the widespread and ancient pollution of our drinking water by arsenite.
  • 1.9K
  • 09 Oct 2020
Topic Review
Artemisia absinthium L.
Artemisia absinthium – wormwood (Asteraceae) – is a very important species in the history of medicine, formerly described in medieval Europe as “the most important master against all exhaustions”. It is a species known as a medicinal plant in Europe and also in West Asia and North America. The raw material obtained from this species is Artemisiae herba and Artemisiae absinthium aetheroleum. The main substances responsible for the biological activity of the herb are: the essential oil, bitter sesquiterpenoid lactones, flavonoids, another bitterness-imparting compounds, azulenes, phenolic acids, tannins and lignans. In the official European medicine, the species is used in both allopathy and homeopathy. In the traditional Asian and European medicine, it has been used as an effective agent in gastrointestinal ailments and also in the treatment of helminthiasis, anaemia, insomnia, bladder diseases, difficult-to-heal wounds, and fever. Today, numerous other directions of biological activity of the components of this species have been demonstrated and confirmed by scientific research, antiprotozoal, antibacterial, antifungal, anti-ulcer, hepatoprotective, anti-inflammatory, immunostimulatory, cytotoxic, analgesic, neuroprotective, antidepressant, procognitive, neurotrophic, and cell membrane stabilizing activities. A. absinthium is also making a successful career as a cosmetic plant. In addition, the importance of this species as a spice plant and valuable additive in the alcohol industry (famous absinthe and vermouth-type wines) has not decreased. The species has also become an object of biotechnological research.
  • 800
  • 27 Jan 2022
Topic Review
Aryl Hydrocarbon Receptor
The aryl hydrocarbon receptor (AhR) was first identified as the intracellular protein that 14 bound and mediated the toxic effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, dioxin) and 15 dioxin-like compounds (DLCs). Subsequent studies show that the AhR plays an important role in 16 maintaining cellular homeostasis and in pathophysiology and there is increasing evidence that the 17 AhR is a important drug target. The AhR binds structurally diverse compounds including 18 pharmaceuticals, phytochemicals, endogenous biochemicals some of which may serve as 19 endogenous ligands. Classification of DLCs and non-DLCs based on their persistence (metabolism), 20 toxicities, binding to wild-type/mutant AhR and structural similarities have been reported. This 21 review provides data suggesting that ligands for the AhR are selective AhR modulators (SAhRMs) 22 which exhibit tissue/cell-specific AhR agonist and antagonist activities and their functional diversity 23 is similar to selective receptor modulators that target steroid hormone and other nuclear receptors.
  • 871
  • 10 Feb 2021
Topic Review
Ascorbic Acid against Chronic Diseases
Ascorbic acid (ASC) is a key nutrient that serves as an antioxidant and a cofactor for numerous enzymatic reactions. However, humans, unlike most mammals, are unable to synthesize it. Consequently, ASC must be obtained through dietary sources, especially fresh fruit and vegetables. The value of administering exogenous micronutrients, to reestablish antioxidant concentrations in patients with severe disease, has been recognized for decades. Despite the suggestion that ASC supplementation may reduce oxidative stress and prevent several chronic conditions, few large, randomized clinical trials have tested it in patients with severe illness. This article reviews the recent literature on the pharmacological profile of ASC and the role of its supplementation in critically ill patients.
  • 598
  • 11 Dec 2020
Topic Review
Astaxanthin as Potential Neurotherapeutic Agent
ASX, a member of the xanthophyll group, was found to be a promising therapeutic anti-inflammatory agent for many neurological disorders, including cerebral ischemia, Parkinson’s disease, Alzheimer’s disease, autism, and neuropathic pain.
  • 1.2K
  • 15 Apr 2021
Topic Review
Asthma and Obesity
Asthma is a common chronic airway disease characterized by variable airflow limitation resulting from the combination of airway narrowing, airway hypersensitivity, airway wall thickening, and increased mucus hypersecretion. Airway narrowing results from both chronic inflammation and airway remodeling. Asthma is a heterogeneous disease with several distinct clinical presentations (phenotypes) and complex pathophysiological mechanisms (endotypes). Obesity is the consequence of an excessive body fat accumulation due to an imbalance of energy intake and energy expenditure. Diagnosis of obesity is usually established by assessing the body mass index (BMI) ≥ 30 kg/m2.
  • 507
  • 22 Feb 2021
Topic Review
Asthma-Polycystic Ovary Overlap Syndrome
Asthma is a heterogeneous inflammatory disease characterized by abnormalities in immune response. Due to the inherent complexity of the disease and the presence of comorbidities, asthma control is often difficult to obtain. In asthmatic patients, an increased prevalence of irregular menstrual cycles, infertility, obesity, and insulin resistance has been reported.
  • 401
  • 21 Jun 2023
Topic Review
Atherosclerosis in Prediabetes
Atherosclerosis is a chronic inflammatory process within the arterial wall.
  • 368
  • 29 Apr 2021
Topic Review
Atorvastatin
Atorvastatin (ATS) is the gold-standard treatment worldwide for the management of hypercholesterolemia and prevention of cardiovascular diseases associated with dyslipidemia.
  • 875
  • 01 Jun 2021
Topic Review
Autophagy in Nanomaterial Toxicity
Nanotechnology has rapidly promoted the development of a new generation of industrial and commercial products; however, it has also raised some concerns about human health and safety. To evaluate the toxicity of the great diversity of nanomaterials (NMs) in the traditional manner, a tremendous number of safety assessments and a very large number of animals would be required. For this reason, it is necessary to consider the use of alternative testing strategies or methods that reduce, refine, or replace (3Rs) the use of animals for assessing the toxicity of NMs. Autophagy is considered an early indicator of NM interactions with cells and has been recently recognized as an important form of cell death in nanoparticle-induced toxicity. Impairment of autophagy is related to the accelerated pathogenesis of diseases. By using mechanism-based high-throughput screening in vitro, we can predict the NMs that may lead to the generation of disease outcomes in vivo. Thus, a tiered testing strategy is suggested that includes a set of standardized assays in relevant human cell lines followed by critical validation studies carried out in animals or whole organism models such as C. elegans (Caenorhabditis elegans), zebrafish (Danio rerio), and Drosophila (Drosophila melanogaster)for improved screening of NM safety. A thorough understanding of the mechanisms by which NMs perturb biological systems, including autophagy induction, is critical for a more comprehensive elucidation of nanotoxicity. A more profound understanding of toxicity mechanisms will also facilitate the development of prevention and intervention policies against adverse outcomes induced by NMs. The development of a tiered testing strategy for NM hazard assessment not only promotes a more widespread adoption of non-rodent or 3R principles but also makes nanotoxicology testing more ethical, relevant, and cost- and time-efficient.
  • 602
  • 28 Oct 2020
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