Keap1, the cysteine-based mammalian intracellular sensor for electrophiles and oxidants

The Kelch-like ECH associated protein 1 (Keap1) is a component of a Cullin3-based Cullin-RING E3 ubiquitin ligase (CRL) multisubunit protein complex. Within the CRL, homodimeric Keap1 functions as the Cullin3 adaptor, and importantly, it is also the critical component of the E3 ligase that performs the substrate recognition. The best-characterized substrate of Keap1 is transcription factor NF-E2 p45-related factor 2 (Nrf2), which orchestrates an elaborate transcriptional program in response to environmental challenges caused by oxidants, electrophiles and pro-inflammatory agents, allowing adaptation and survival under stress conditions. Keap1 is equipped with reactive cysteine residues that act as sensors for endogenously produced and exogenously encountered small molecules (termed inducers), which have a characteristic chemical signature, reactivity with sulfhydryl groups. Inducers modify the cysteine sensors of Keap1 and impair its ability to target Nrf2 for ubiquitination and degradation. Consequently, Nrf2 accumulates, enters the nucleus and drives the transcription of its target genes, which encode a large network of cytoprotective proteins. Here we summarize the early studies leading to the prediction of the existence of Keap1, followed by the discovery of Keap1 as the main negative regulator of Nrf2. We then describe the available structural information on Keap1, its assembly with Cullin3, and its interaction with Nrf2. We also discuss the multiple cysteine sensors of Keap1 that allow for detection of a wide range of endogenous and environmental inducers, and provide fine-tuning and tight control of the Keap1/Nrf2 stress-sensing response

Mean Age of Patients with and without Type 2 Diabetes Mellitus during Surgical Treatment of Age-Related Cataract

Introduction: Age-related cataract is one of the most common causes of preventable blindness. Type 2 diabetes is a non-infectious epidemic disease with an ever-increasing number of diseased patients. Cataract is one of the leading causes of reduced vision in diabetics. The preferred treatment method is phacoemulsification. The aim of the present study was to compare the mean age of patients with and without diabetes type 2 at the time of cataract surgery. Materials and methods: After informed consent and approval by the Ethics Commission of the Medical University of Sofia, 176 patients admitted to the Clinic of Ophthalmology at the University Hospital „Alexandrovska“ for surgical treatment of cataract were randomized. Inclusion criteria: diagnosed age-related cataract, requiring surgical treatment. Patients were divided into two groups – diabetic type 2 and non-diabetic patients. Inclusion criteria for the group of diabetics: medical history of diabetes type 2 and administration of anti diabetic medications. Results: The average age of patients undergoing cataract surgery was 70.81 years. The average ageof patients with diabetes type 2 was 65.89 years, and that of non-diabetics – 71.74 years. Diabetes type 2 was established at 15.91 % of patients (19 men and 9 women). Conclusion: Patients with diabetes type 2 develop age-related cataract, requiring surgical treatment, at an earlier age compared to non-diabetics. The transparency of the lens in diabetic patients is of particular importance for the diagnosis and treatment of the diabetic retinopathy. Follow-up by an ophthalmologist and maintenance of strict blood glucose control are necessary to reduce the incidence of vision loss, caused by cataract and diabetic retinopathy

The multifaceted role of Nrf2 in mitochondrial function

Oxidative ToxicologyThe transcription factor nuclear factor erythroid 2 p45-related factor 2 (Nrf2) is the master regulator of the cellular redox homeostasis. Nrf2 target genes comprise of a large network of antioxidant enzymes, proteins involved in xenobiotic detoxification, repair and removal of damaged proteins, inhibition of inflammation, as well as other transcription factors. In recent years it has emerged that as part of its role as a regulator of cytoprotective gene expression, Nrf2 impacts mitochondrial function. Increased Nrf2 activity defends against mitochondrial toxins. Reduced glutathione, the principal small molecule antioxidant in the mammalian cell and a product of several of the downstream target genes of Nrf2, counterbalances mitochondrial ROS production. The function of Nrf2 is suppressed in mitochondria-related disorders, such as Parkinson's disease and Friedrich's ataxia. Studies using isolated mitochondria and cultured cells have demonstrated that Nrf2 deficiency leads to impaired mitochondrial fatty acid oxidation, respiration and ATP production. Small molecule activators of Nrf2 support mitochondrial integrity by promoting mitophagy and conferring resistance to oxidative stress-mediated permeability transition. Excitingly, recent studies have shown that Nrf2 also affects mitochondrial function in stem cells with implications for stem cell self-renewal, cardiomyocyte regeneration, and neural stem/progenitor cell survival.Peer reviewe

Childhood glaucoma

Въведение: Глаукомата в детска възраст е сравнително рядко, но сериозно застрашаващо зрението заболяване. По литературни данни засяга 1 на 10 000 до 12 500 новородени. Заболяването има значителни различия по отношение на етиопатогенезата, клиниката и лечението в сравнение с глаукомата при възрастни. Цел: Целта на настоящата статия е да представи алгоритъм за диагностика и проследяване на деца с глаукома, както и резултатите от изследване на деца с първична конгенитална глаукома. Материали и Методи: Под обща маскова анестезия са изследвани 18 очи на 9 деца. Изследвани са вътреочното налягане, централната роговична дебелина и хоризонтален роговичен диаметър. Резултати: При 3 от децата заболяването засяга само едното око, a при останалите 6 и двете очи. Средната възраст на изследваните деца е 6 месеца и 5 дни. Заключение: Глаукомата в детска възраст е актуален, значим, широко дискутиран медико-социален проблем. При всички деца с глаукома или съмнение за такава трябва да се предложи пакет от изследвания, които се правят в определена последователност, струват пари и отнемат време. Без тяхна помощ обаче е абсолютно невъзможна правилната диагноза, стадирането на болестта и предлагането на адекватна терапия. Повече от половината от пациентите с ПКГ стигат до слепота.Introduction: Childhood glaucoma is a relatively rare but seriously sight threatening disease. According to the literature it affects 1 out of 10 000 to 12 500 newborns. It has ethiopathological, clinical and therapeutic differences from the adult glaucoma. Aim: The aim of the current study is to present an algorithm for diagnosis and follow-up of patients with glaucoma and the results of the examination of 9 children with primary congenital glaucoma Methods and Materials: We have examined under general mask anestesia 18 eyes of 9 children (3 boys and 6 girls): intraocular pressure of each eye; central corneal sickness and horizontal corneal diameter. Results: Three of the children had unilateral disease and in the rest the diseases affected both eyes. The average age of the examined children was 6 months and 5 days. Conclusion: Childhood glaucoma is a relevant, significant and widely-discussed medico-social problem. In all cases of children with glaucoma or suspicion for such a package of tests should be performed which are costly and time-consuming. However, without these tests it is absolutely impossible to give an accurate diagnosis and hence initiate a proper therapy. More than half of the patients with primary congenital glaucoma become blind

Influence of sulphate ions on the crystal chemistry of white cement mortars with a high content of marble filler powder

Objects of this research are white cement mortars, characterized by both of high content of addition of marble powder and reduced water-cement ratio. The hardened cement mortars,formed after 28-and 120-day curing under standard conditions, are studied. The newlyformed phases, containing [SO4]2-, [CO3]2-, [OH]-, etc., are identified using X-ray powder diffraction, infrared spectroscopy and thermal analysis (coupled with analysis of the outgoing gas mixture by mass spectrometry). Based on of the formed calcium silicate hydrates, calcium aluminate hydrates, the influence of sulphate ions is analysed and the mechanism of the thermal decomposition reaction at high temperatures in an oxidizing gas environment is studied. This allows us to establish that the hydration of Portland cement depends on the addition of marble powder (technically calcium carbonate CaCO3), as well as mono-and hemicarboaluminates are formed instead of monosulphoaluminates

Suboptimal paths in the problem of a planar motion with bounded derivative of the curvature

We consider the planar motion of a car-like robot with a bounded derivative of the curvature, with given initial and final configuration (i.e. positions, tangent angles and curvatures). The tangent angle and the curvature of the path are assumed to be continuous. When the distance between the initial and the final point is much greater than the initial and final curvatures and the curvature's derivative, we show how to construct a suboptimal path (the cost is the path length). We admit a finite number of cusps in the path

Advantages of using modern online booking systems in tourism

У статті розглянуто значення систем онлайн-бронювання в діяльності підприємств туристичної індустрії та гостинності. Визначено переваги їх використання для бронювання туристичних та готельних послуг через мережу інтернет, в інтерактивному режимі. Окреслено і деякі обмеження щодо надання цих послуг у режимі онлайн в Україні.The article examines the importance of online booking systems in the activities of enterprises in the tourism industry and hospitality. The advantages of their use for booking tourist and hotel services via the Internet, in an interactive mode, have been determined. Some restrictions on the provision of these services online in Ukraine are also outlined

Pharmacokinetics and pharmacodynamics of orally administered acetylenic tricyclic <i>bis</i>(cyanoenone), a highly potent Nrf2 activator with a reversible covalent mode of action

AbstractThe acetylenic tricyclic bis(cyanoenone) TBE-31 is a highly potent cysteine targeting compound with a reversible covalent mode of action; its best-characterized target being Kelch-like ECH-associated protein-1 (Keap1), the cellular sensor for oxidants and electrophiles. TBE-31 reacts with cysteines of Keap1, impairing its ability to target nuclear factor-erythroid 2 p45-related factor 2 (Nrf2) for degradation. Consequently, Nrf2 accumulates and orchestrates cytoprotective gene expression. In this study we investigated the pharmacokinetic and pharmacodynamic properties of TBE-31 in C57BL/6 mice. After a single oral dose of 10 μmol/kg (∼200 nmol/animal), the concentration of TBE-31 in blood exhibited two peaks, at 22.3 nM and at 15.5 nM, 40 min and 4 h after dosing, respectively, as determined by a quantitative stable isotope dilution LC-MS/MS method. The AUC0–24h was 195.5 h/nmol/l, the terminal elimination half-life was 10.2 h, and the kel was 0.068 h−1. To assess the pharmacodynamics of Nrf2 activation by TBE-31, we determined the enzyme activity of its prototypic target, NAD(P)H:quinone oxidoreductase 1 (NQO1) and found it elevated by 2.4- and 1.5-fold in liver and heart, respectively. Continuous feeding for 18 days with diet delivering the same daily doses of TBE-31 under conditions of concurrent treatment with the immunosuppressive agent azathioprine had a similar effect on Nrf2 activation without any indications of toxicity. Together with previous reports showing the cytoprotective effects of TBE-31 in animal models of carcinogenesis, our results demonstrate the high potency, efficacy and suitability for chronic administration of cysteine targeting reversible covalent drugs

Targeted expression of human FSH receptor Asp567Gly mutant mRNA in testis of transgenic mice: role of the human FSH receptor promoter.

AIM: To specifically express the Asp567Gly human follicle-stimulating hormone receptor (FSHR) under the control of its promoter to evaluate the phenotypic consequences in the presence of normal pituitary function. METHODS: We produced transgenic mice overexpressing the Asp567Gly human FSHR under the control of a 1.5kb 5'-flanking region fragment of its promoter. RESULTS: Mice were phenotypically normal and fertile. In males, mRNA could be detected in the testis and the brain, indicating that the 1.5kb promoter fragment drives expression not only in the gonads. The testis weight/body weight ratio and the testosterone levels in transgenic and non-transgenic littermates were similar. By in situ hybridisation we found that the transgenic FSHR was highly expressed in Sertoli cells, spermatocytes and round spermatids. However, a radioligand receptor assay failed to show a significant difference in total FSHR binding sites in testis homogenates of transgenic and wild type animals, suggesting that the transgenic FSHR is probably not translated into functional receptor protein. CONCLUSION: A 1.5kb 5'-region of the human FSHR drives mRNA expression of the transgene in the testis but leads to ectopic expression in germ cells and in the brain. No phenotypic consequences could be documented due to the lack of protein expression