The xenobiotic-metabolizing enzymes arylamine N-acetyltransferases in human lens epithelial cells: inactivation by cellular oxidants and UVB-induced oxidative stress

The abbreviations used are: NAT, arylamine N-acetyltransferase; XME, xenobiotic-metabolizing enzymes; SIN1, 3-morpholinosydnonimine N-ethylcarbamide MOL 9738 3 ABSTRACT The human arylamine N-acetyltransferases NAT1 and NAT2 are important xenobioticmetabolizing enzymes involved in the detoxification and metabolic activation of numerous drugs and chemicals. NAT activity depends on genetic polymorphisms and on environmental factors. It has been shown that low NAT-acetylation activity could increase the risk of age-dependent cataract suggesting that NAT detoxification function may be important for lens cells homeostasis. We report here that the NAT acetylation pathway may occur in human lens epithelial (HLE) cells. Functional NAT1 enzyme was readily detected in HLE cells by RT-PCR, western-blotting and enzyme activity assays. NAT2 mRNA and enzymic activity was also detected. We investigated whether oxidants, known to be produced in HLE cells during oxidative stresses and involved in age-dependent cataract formation, decreased endogenous NAT1 and NAT2 activity. The exposure of HLE cells to peroxynitrite led to the dose-dependent irreversible inactivation of both NAT isoforms. Exposing HLE cells to continuously generated H 2 O 2 gave a dose-dependent inactivation of NAT1 and NAT2, reversible on addition of high concentrations of reducing agents. UVB irradiation also induced the reversible dose-dependent inactivation of endogenous NAT1 and NAT2, reversible on addition of reducing agents. Thus, our data suggest that functional NAT1 and NAT2 are present in HLE cells and may be impaired by oxidants produced during oxidative and photo-oxidative stresses. Oxidative-dependent inhibition of NATs in these cells may increase exposure of lens to the harmful effects of toxic chemicals which could contribute to cataractogenesis over time

The Bacillus anthracis arylamine N-acetyltransferase ((BACAN)NAT1) that inactivates sulfamethoxazole, reveals unusual structural features compared with the other NAT isoenzymes

AbstractArylamine N-acetyltransferases (NATs) are xenobiotic-metabolizing enzymes that biotransform arylamine drugs. The Bacillus anthracis (BACAN)NAT1 enzyme affords increased resistance to the antibiotic sulfamethoxazole through its acetylation. We report the structure of (BACAN)NAT1. Unexpectedly, endogenous coenzymeA was present in the active site. The structure suggests that, contrary to the other prokaryotic NATs, (BACAN)NAT1 possesses a 14-residue insertion equivalent to the “mammalian insertion”, a structural feature considered unique to mammalian NATs. Moreover, (BACAN)NAT1 structure shows marked differences in the mode of binding and location of coenzymeA when compared to the other NATs. This suggests that the mechanisms of cofactor recognition by NATs is more diverse than expected and supports the cofactor-binding site as being a unique subsite to target in drug design against bacterial NATs

The xenobiotic-metabolizing enzymes arylamine N-acetyltransferases in human lens epithelial cells: inactivation by cellular oxidants and UVB-induced oxidative stress

ABSTRACT The human arylamine N-acetyltransferases NAT1 and NAT2 are important xenobiotic-metabolizing enzymes involved in the detoxification and metabolic activation of numerous drugs and chemicals. NAT activity depends on genetic polymorphisms and on environmental factors. It has been shown that low NAT-acetylation activity could increase the risk of age-dependent cataract, suggesting that NAT detoxification function may be important for lens cells homeostasis. We report here that the NAT acetylation pathway may occur in human lens epithelial (HLE) cells. Functional NAT1 enzyme was readily detected in HLE cells by reverse transcription-polymerase chain reaction, Western blotting, and enzyme activity assays. NAT2 mRNA and enzymic activity were also detected. We investigated whether oxidants, known to be produced in HLE cells during oxidative stresses and involved in age-dependent cataract formation, decreased endogenous NAT1 and NAT2 activity. The exposure of HLE cells to peroxynitrite led to the dose-dependent irreversible inactivation of both NAT isoforms. Exposing HLE cells to continuously generated H 2 O 2 gave a dose-dependent inactivation of NAT1 and NAT2, reversible on addition of high concentrations of reducing agents. UVB irradiation also induced the reversible dose-dependent inactivation of endogenous NAT1 and NAT2, reversible on addition of reducing agents. Thus, our data suggest that functional NAT1 and NAT2 are present in HLE cells and may be impaired by oxidants produced during oxidative and photooxidative stresses. Oxidativedependent inhibition of NATs in these cells may increase exposure of lens to the harmful effects of toxic chemicals that could contribute to cataractogenesis over time

Immunosuppressive therapy after solid-organ transplantation: does the INTERMED identify patients at risk of poor adherence?

Lack of adherence to medication is a trigger of graft rejection in solid-organ transplant (SOT) recipients. This exploratory study aimed to assess whether a biopsychosocial evaluation using the INTERMED instrument before transplantation could identify SOT recipients at risk of suboptimal post-transplantation adherence to immunosuppressant drugs. We hypothesized that complex patients (INTERMED>20) might have lower medication adherence than noncomplex patients (INTERMED≤20). Each patient eligible for transplantation at the University Hospital of Lausanne, Switzerland, has to undergo a pre-transplantation psychiatric evaluation. In this context the patient was asked to participate in our study. The INTERMED was completed pre-transplantation, and adherence to immunosuppressive medication was monitored post-transplantation by electronic monitors for 12 months. The main outcome measure was the implementation and persistence to two calcineurin inhibitors, cyclosporine and tacrolimus, according to the dichotomized INTERMED score (>20 or ≤20). Among the 50 SOT recipients who completed the INTERMED, 32 entered the study. The complex (N=11) and noncomplex patients (N=21) were similar in terms of age, sex and transplanted organ. Implementation was 94.2% in noncomplex patients versus 87.8% in complex patients (non-significant p-value). Five patients were lost to follow-up: one was non-persistent, and four refused electronic monitoring. Of the four patients who refused monitoring, two were complex and withdrew early, and two were noncomplex and withdrew later in the study. Patients identified as complex pre-transplant by the INTERMED tended to deviate from their immunosuppressant regimen, but the findings were not statistically significant. Larger studies are needed to evaluate this association further, as well as the appropriateness of using a nonspecific biopsychosocial instrument such as INTERMED in highly morbid patients who have complex social and psychological characteristics

Enteric Neurospheres Are Not Specific to Neural Crest Cultures: Implications for Neural Stem Cell Therapies

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited

Open access in Southern European countries

The Spanish Foundation for Science and Technology (FECYT) is a public foundation under the Spanish Ministry of Science and Innovation whose mission is to strengthen the value chain of knowledge by fostering science and innovation and trying to integrate them and bring them closer to society, in response to the needs and expectations of the Spanish science, technology and enterprise system. The Foundation’s goal is to be recognized by Spanish society as a key reference in the dissemination, information and measurement of science and innovation. It also wishes to contribute to the development of a knowledge-based economy. One of the main challenges of the Foundation is to lead the integration and rationalization of scientific information and science, technology and innovation metrics, described as the “integrate and measure vector” in its 2010- 2012 strategic plan. FECYT already has considerable experience in managing national scientific information. It is the national licensee of the Thomson Reuters Web of Knowledge accessed by the Spanish scientific community. It is also firmly committed to establishing itself as the Spanish hub in favour of the open access (OA) movement (for free access to scientific information available on the Internet), in combination with supporting the traditional markets of scientific information. In 2010 FECYT organized the 5th International Conference on Open Repositories in Madrid, with the aim of positioning Spain in the debate on emerging trends in the management of scientific information. The authorities are opening the door to the open access movement, under the belief that publicly funded research should be freely available. Among other initiatives, the 2010 Spanish Bill on Science, Technology and Innovation urges researchers to deposit their research papers produced with public funding in institutional repositories

Market opportunities for octopus in the Atlantic area: Cephs & Chefs: summary of main achievements

Sem resumo disponível.INTERREG Atlantic Area (EAPA 282/2016)publishe