Application of Polymer Membranes for a Purification of Fuel Oxygenated Additive. Methanol/Methyl Tert-butyl Ether (MTBE) Separation via Pervaporation: A Comprehensive Review

Methyl Tert-butyl Ether (MTBE) remains the most popular fuel additive to improve fuel performance and reduce the emission of hazardous components. The most common method of MTBE production is a catalytic synthesis with a great excess of methanol to improve the reaction yield. The problems of obtaining pure MTBE from the final product have determined the search for new techniques; primarily membrane methods. Pervaporation as an optimal membrane process for highly selective separation of organic mixtures is of particular interest. This review is focused on analysis of the research works on the various polymer membranes and their efficiency for the separation of the azeotropic methanol/MTBE mixture. Currently the most popular materials with optimal transport properties are poly(vinyl alcohol), cellulose acetate and polyheteroarylenes. Mixed matrix membranes (MMM) are highly effective as well as they show overall operational stability.

Flavonoids with Glutathione Antioxidant Synergy: Influence of Free Radicals Inflow

This report explores the antioxidant interaction of combinations of flavonoid–glutathione with different ratios. Two different 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid radical (ABTS•+)-based approaches were applied for the elucidation of the antioxidant capacity of the combinations. Despite using the same radical, the two approaches employ different free radical inflow systems: An instant, great excess of radicals in the end-point decolorization assay, and a steady inflow of radicals in the lag-time assay. As expected, the flavonoid–glutathione pairs showed contrasting results in these two approaches. All the examined combinations showed additive or light subadditive antioxidant capacity effects in the decolorization assay. This effect showed slight dilution dependence and did not change when the initial ABTS•+ concentration was two times as high or low. However, in the lag-time assay, different types of interaction were detected, from subadditivity to considerable synergy. Taxifolin–glutathione combinations demonstrated the greatest synergy, at up to 112%; quercetin and rutin, in combination with glutathione, revealed moderate synergy in the 30–70% range; while morin–glutathione appeared to be additive or subadditive. In general, this study demonstrated that, on the one hand, the effect of flavonoid–glutathione combinations depends both on the flavonoid structure and molar ratio; on the other hand, the manifestation of the synergy of the combination strongly depends on the mode of inflow of the free radicals.

Gestational Diabetes Review: Maternal-fetal Comorbidities and Treatment with Medicinal Plants

Gestational Diabetes is a condition characterized by hyperglycemia that provides a drop-in insulin performance in its appropriate receptors by hormones secreted by the placenta and fetus. The main fetal comorbidities are macrosomia, growth disorder, and congenital and maternal anomalies in gestational diabetes, preeclampsia, vascular injury, and post-gestational diabetes. This study addressed the possible treatments with medicinal plants in gestational diabetes. Medicinal plants that have the diabetic purpose were researched, however, many pregnant women use and do not know the effects that can happen for the fetus and also for itself, the plants used for this work is not satisfactory for pregnant women with diabetes, but for non-diabetics, some are beneficial for treating this pathology. It becomes necessary for people to know the effects of plants that are used to treat certain types of diseases because most often in great excess can be fatal. All of them presented satisfactory results in a study for diabetes mellitus in non-pregnant patients, but the study presented by Cow's Paw (Bauhinia forficata l.) in pregnant rats with diabetes showed harmful results in embryo implantation and there was no glycemic control, which leads us to investigate further under the use of all plants in the treatment of gestational diabetes.

Ab Initio Modelling the Structure of Proton-Sensing G-Protein Coupled Receptor GPR151

Protein is the proteios building block of life. Evolutionarily, its sequence is not as conserved as its structure, making it more reasonable for protein structure, instead of protein sequence, to be the descriptor of protein function. Yet, in the National Center for Biotechnology Information (NCBI) database, the number of experimentally identified protein sequences is in great excess of that of experimentally determined protein structures inside the almost-half-a-century old Protein Data Bank (PDB). For instance, GPR151 is an proton-sensing G-protein coupled receptor (GPCR) originally identified as homologous to galanin receptors. As of March 19, 2020, GPR151’s structure has not been experimentally determined and deposited in PDB yet. Thus, an ab initio modelling approach was employed here to build a three-dimensional structure of GPR151. Overall, the ab initio GPR151 model presented herein constitutes the first structural hypothesis of GPR151 to be experimentally tested in future with previously published, currently ongoing and future GPR151 studies.

Porphyria

This chapter discusses six diseases caused by inborn errors of metabolism affecting the biosynthesis of haem. Haem is a tetracyclic metal-binding compound involved in oxygen transport (in haemoglobin and myoglobin) and redox reactions (e.g. in the cytochrome P450 system). Each of these conditions is caused by a single gene defect in one of the enzymes involved in the biosynthesis of haem. Inheritance is usually autosomal dominant with incomplete penetrance. The enzyme defect results in disease, not as a result of deficiency of the reaction product, but as a result of accumulation of precursors. Early, soluble precursors, 5-aminolaevulinic acid, and porphobilinogen (not porphyrins as such) are neurotoxic and, when present in great excess, as occurs when flux through the haem synthetic pathway is increased in response to particular medications or hormones, lead to acute neurovisceral crises. Later cyclical precursors (porphyrins) in the pathway are also water soluble and excreted in urine, but are susceptible to activation by electromagnetic radiation in the visible spectrum and are converted to free-radical metabolites that cause pain, inflammation, and tissue damage in the skin. The final haem precursors (also porphyrins) are hydrophobic and excreted in the bile and faeces and are also activated by light to toxic metabolites.

Sofosbuvir and Ribavirin Liver Pharmacokinetics in Patients Infected with Hepatitis C Virus

ABSTRACT Sofosbuvir and ribavirin exert their anti-hepatitis C virus (anti-HCV) activity following metabolic activation in the liver. However, intrahepatic concentrations of the pharmacologically active nucleotide metabolites in humans are poorly characterized due to the inaccessibility of tissue and technical challenges with measuring nucleotide levels. A clinical study assessing the efficacy of sofosbuvir and ribavirin administered prior to liver transplantation to prevent HCV recurrence provided a unique opportunity to quantify nucleotide concentrations in human liver. We analyzed nucleotides using high-performance liquid chromatography coupled to tandem mass spectrometry in liver tissue from 30 HCV-infected patients with hepatocellular carcinoma who were administered sofosbuvir (400 mg/day) and ribavirin (1,000 to 1,200 mg/day) for 3 to 52 weeks prior to liver transplantation. Median total hepatic metabolite concentrations (the sum of nucleoside and mono-, di-, and triphosphates) were 77.1 μM for sofosbuvir and 361 μM for ribavirin in patients on therapy at the time of transplantation. Ribavirin and sofosbuvir efficiently loaded the liver, with total hepatic metabolite concentrations exceeding maximal levels in plasma by approximately 30-fold. Ribavirin metabolite levels suggest that its monophosphate is in great excess of its inhibition constant for IMP dehydrogenase and that its triphosphate is approaching the binding constant for incorporation by the HCV NS5B RNA-dependent RNA polymerase. In accordance with the potent antiviral activity of sofosbuvir, these results demonstrate that the liver triphosphate levels achieved following sofosbuvir administration greatly exceed the inhibition constant for HCV NS5B. In conclusion, this study expands the quantitative understanding of the pharmacology of sofosbuvir and ribavirin by establishing efficient hepatic delivery in the clinic. (This study has been registered at ClinicalTrials.gov under identifier NCT01559844.)

Genomic epidemiology of artemisinin resistant malaria

The current epidemic of artemisinin resistant Plasmodium falciparum in Southeast Asia is the result of a soft selective sweep involving at least 20 independent kelch13 mutations. In a large global survey, we find that kelch13 mutations which cause resistance in Southeast Asia are present at low frequency in Africa. We show that African kelch13 mutations have originated locally, and that kelch13 shows a normal variation pattern relative to other genes in Africa, whereas in Southeast Asia there is a great excess of non-synonymous mutations, many of which cause radical amino-acid changes. Thus, kelch13 is not currently undergoing strong selection in Africa, despite a deep reservoir of variations that could potentially allow resistance to emerge rapidly. The practical implications are that public health surveillance for artemisinin resistance should not rely on kelch13 data alone, and interventions to prevent resistance must account for local evolutionary conditions, shown by genomic epidemiology to differ greatly between geographical regions.