Zielstellung dieser Studie war es zu überprüfen, ob durch Fütterung einer mit Vitamin E und Selen angereicherten Mineralstoffmischung in der Transitphase eine Beeinflussung des antioxidativen Status mit Reaktionen GPX [Glutathionperoxidase], SOD [Superoxiddismutase], TEAC [Trolox equivalent antioxidative capacity] und ACW [nichtenzymatische wasserlösliche Antioxidantien] sowie des Stoffwechsels erreicht werden kann und ob damit die Häufigkeit der in der Frühlaktation typischen Erkrankungen sinkt. Zur Beantwortung dieser Fragestellung wurden in einem Milchviehbestand mit 1400 Kühen und Färsen zwei Gruppen von je 26 Tieren zu Beginn der Transitfütterung zusammengestellt. Die Versuchsgruppe erhielt drei Wochen ante partum bis drei Wochen post partum eine Mineralstoffmischung mit einem Vitamin E- Gehalt von 300 mg/kg TM (= 447 IU /kg TM) und einem Selengehalt von 0,5 mg/ kg TM, die Kontrollgruppe die stallübliche Mineralstoffmischung mit 0,3 mg Selen/kg TM ohne zusätzliche Vitamin E Ergänzung. Jedem Tier wurde drei Wochen ante partum, 2 bis 4 Tage post partum und 3 Wochen post partum zur klinisch- chemischen Kontrolle Blut entnommen.Zur Bestimmung des antioxidativen Status wurden die GPX, SOD, TEAC und ACW untersucht. Zur Bewertung des peripartalen Stoffwechsels wurden die Parameter des Energie-, Fett- und Leberstoffwechsels (BHB [ß-0H-Butyrat], Cholesterol, AST [Aspartat-Amino-Transferase], GLDH [Glutamat- Dehydrogenase]), des Eiweißstoffwechsels (Albumin, TP [Gesamt-Eiweiß]), sowie des Mineralstoffwechsels (Ca [Calcium], Pi [anorganisches Phosphat] und der CK [Creatinkinase] bestimmt und mit den Kühen der Kontrollgruppe verglichen. Im Blutbild wurden die Erythrozytenzahl, die Leukozytenzahl, die Erythrozytenindices (MCH, MCHC, MCV), Hämatokrit, Hämoglobin und Thrombozytenzahlen verglichen. Die Häufigkeit des Auftretens der klinischen Krankheitsbilder Mastitis, Gebärparese, Retentio secundinarum, Klauenerkrankungen und puerperale Septikämie und die Produktionsdaten Milchleistung nach 100 Tagen, Milchleistung nach 305 Tagen und Zwischenkalbezeit wurden nach Ende der Untersuchungen statistisch ausgewertet. Eine direkte Beeinflussung des SOD und der GPX ist möglich. Durch die Gabe der mit Vitamin E und Selen angereicherten Mineralstoffmischung konnte in der Versuchsgruppe ein Anstieg der GPX-Aktivität und eine Plateaubildung erreicht werden. Die SOD-Aktivitäten lagen in der Versuchsgruppe drei Wochen post partum signifikant höher als in der Kontrollgruppe. Eine bessere Adaptation an den oxidativen Stress im peripartalen Zeitraum kann durch eine mit Vitamin E und Selen angereicherte Mineralstoffmischung erreicht werden. Die Inzidenz der Mastitiserkrankungen in der Frühlaktation wurde signifikant gesenkt.Die Inzidenz der Mastitiserkrankungen in der Frühlaktation wurde signifikant gesenkt. Signifikante Unterschiede ergaben sich auch in der Aktivität der GLDH. In der Versuchsgruppe wurden 3 Wochen post partum deutlich niedrigere GLDH- Aktivität gemessen als in der Kontrollgruppe, woraus auf einen besseren Leberzellschutz in der kritischen biologischen Phase der Milchkuh zu schließen ist. Hinsichtlich der Häufigkeit des Auftretens weiterer klinischer Erkrankungen im peripartalen Zeitraum konnte jedoch keine Verbesserung erzielt werden. Ebenso haben sich die Produktionsparameter Milchleistung und Zwischenkalbezeit nicht verbessert.

Trotz intensiver Forschung ist die Ätiologie der sporadischen amyotrophen Lateralsklerose (sALS) weiterhin unbekannt. Zahlreiche Anzeichen deuten allerdings auf eine Mitbeteiligung von oxidativem Streß an der Pathogenese der sALS hin. So fand sich eine verminderte Aktivität der zellulären Glutathion-Peroxidase (GPX-1), eines als Radikalenfänger fungierenden Enzyms, in den Gyrus praecentrales bei sALS-Patienten. Zusätzliche Studien fanden eine Trinukleotid-Expansion des GGG-repeats im 1. Exon des für die GPX-1 kodierenden Gens. Da Trinukleotid-Expansionen bei einer Vielzahl von neurodegenerativen Erkrankungen wie dem Kennedy-Syndrom und der spinozerebellären Ataxie nachgewiesen werden konnten, war das Ziel dieser Arbeit, eine fragliche Mitbeteiligung dieser Trinkukleotid-Expansion der GPX-1 an der Pathogenese der sALS zu klären. Nach Etablierung der Methode bestehend aus einer Kombination von Polymerase-Kettenreaktion (PCR) und Restriktions-Fragment-Längen-Polymorphismus (RFLP) zeigte sich, dass der Genotyp 4*5 bei einer Gruppe von 231 sALS-Patienten signifikant häufiger vertreten war, wohingegen der Genotyp 5*6 in der Kontrollgruppe signifikant überrepräsentiert war. Im Vergleich zu bisher veröffentlichten Ergebnissen ließ sich der Genotyp 4*4 in der Kontrollgruppe signifikant häufiger nachweisen. Ursache hierfür könnte - neben einem tatsächlich erhöhten Risiko, an sALS zu erkranken - der Zusammenhang mit einem C/T-Polymorphismus der GPX-1 sein, der zu einem Austausch von Prolin zu Leucin führt. Die für Leucin kodierende Variante tritt hierbei nur zusammen mit 5 GCG-repeats auf, während die für Prolin kodierende Variante mit dem Auftreten von 4 und 6 GCG-repeats korreliert. / In spite of intensive research efforts the ethiology of sporadic amyotrophic lateral sclerosis (sALS) remains unknown. Various indices indeed suggest an involvement of oxidative stress in the pathogenesis of sALS. Thus a decreased activity of the cellular glutathione peroxidase (GPX-1) in gyrus praecentrales of sALS patients could be detected, an enzym strongly participating in the clearence of free radicals. Additional studies uncovered a trinucleotid expansion of a GCG repeat in the 1st exon of the gene coding for GPX-1. Such trinucleotid expansions play a major role in a variety of neurodegenerative disorders like the Kennedy Syndrom and spinal-cerebellary ataxia. Goal of this work was to disclose a possible involvement of the GCG expansion in the pathogenesis of sALS. Through the successful establishment of the methodology consisting of a combination of polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) we could demonstrate a significant decrease of the genotype 4*5 in a group of 231 sALS patients, whereas the genotype 5*6 was overrepresented in the control group. Compared to hitherto publications we detected an increased occurrence of the 4*4 genotype in the control group. Besides an effective increased risk to contract sALS, the distribution of the GCG-repeat expansion could originate from another C/T polymorphism of GPX-1-gene leading to a substitution of proline with leucine. The leucine coding mutation occurs together with 5 GCG repeats, whereas the proline coding mutant correlates with 4 and 6 GCG-repeats.

No description available.

The three insecticides of interest were lindane (an organochlorine), malathion (an organophosphate) and piperonyl butoxide (PBO; a synergist). Based on minimum cytotoxicity (> LC25), the following concentrations were chosen for the pesticide mixture studies: 70μM lindane (Lind), 50μM malathion (Mal) and 55μM PBO. In the AlamarBlue cytotoxicity assay, individual pesticide and mixtures of malathion/PBO (MP) and malathion/lindane (ML) prompted cytotoxicity with varying intensities (Mal 18.8%, Lind 20.4%, PBO 23.5%, ML 53.6% and MP 64.9%). Cytopathological analysis revealed apoptotic features in treated cells and the DNA Ladder Assay confirmed the presence of DNA fragments. The specific mode of cell death was examined via the 7-aminoactinomycin D (7-AAD) Staining Assay. Apoptosis was detected in each treatment (Mal 6.5%, Lind 12.0%, PBO 13.2%, ML 19.3% and MP 23.4%). Furthermore, 7-AAD staining in combination with fluorescent-labeled monoclonal antibodies, PE-CD45RB/220 and FITC-CD90, was performed. B-cells were more susceptible to Mal and PBO treatments than were T-cells. The pro-oxidant activity of the pesticides was monitored via the Dichlorofluorescin Diacetate assay. Exposure to pesticides for 15 minutes increased H2O2 production above the controls, Mal 21.1%; Lind 10.8%; PBO 25.9%; ML 26.8%; MP 37.8%. The activities of antioxidant enzymes, glutathione peroxidase (GSH-Px) and glutathione reductase (GR) were altered by these treatments. GR was significantly reduced for the pesticide mixtures only (control: 51.7; Mal: 48.2; Lind: 50; PBO: 52.3; ML: 40.5; MP: 42 Units/mg). GSH-Px activity was severely reduced for all the pesticide treatments (control: 44.9; Mal: 30.2; Lind: 30.6; PBO: 32.4; ML: 21.1; MP: 21.1 Units/mg). These results indicate that exposure to these pesticide and pesticide mixtures induces apoptosis and oxidative stress. / Master of Science

<p>Women with pregestational diabetes have a 2-5 fold increased risk of giving birth to malformed babies compared with non-diabetic women. Diabetes-induced oxidative stress in maternal and embryonic tissues has been implicated in the teratogenic process. The malformations are likely to be induced before the seventh week of pregnancy, when the yolk sac is partly responsible for the transfer of metabolites to the embryo, and the uterine blood flow to the implantation site determines the net amount of nutrients available to the conceptus. We aimed to evaluate the effect on embryogenesis caused by a diabetes-induced disturbance in yolk sac morphology, uterine blood flow or altered maternal antioxidative status in conjunction with a varied severity of the maternal diabetic state.</p><p>We investigated to which extent maternal diabetes with or without folic acid (FA) supplementation affects mRNA levels and protein distribution of ROS scavenging enzymes (SOD, CAT, GPX), vascular endothelial growth factor-A (Vegf-A), folate binding protein-1 (Folbp-1), and apoptosis associated proteins (Bax, Bcl-2, Caspase-3) in the yolk sacs of rat embryos on gestational days 10 and 11. We found that maternal diabetes impairs, and that FA supplementation restores, yolk sac vessel morphology, and that maternal diabetes is associated with increased apoptotic rate in embryos and yolk sacs, as well as impaired SOD gene expression. We assessed uterine blood flow with a laser-Doppler-flow-meter and found increased blood flow to implantation sites of diabetic rats compared with controls. Furthermore, resorbed and malformed offspring showed increased and decreased blood flow to their implantation sites, respectively. In mice with genetically altered CuZnSOD levels, maternal diabetes increased embryonic dysmorphogenesis irrespective of CuZnSOD expression. We thus found the maternal diabetic state to be a major determinant of diabetic embryopathy and that the CuZnSOD status exerts a partial protection for the embryo in diabetic pregnancy. </p>

A nefropatia diabética (ND) é uma das principais causas de nefropatia crônica, o que torna o diabetes mellitus (DM) responsável por 44% da prevalência de doença renal crônica (DRC) no mundo. O papel do estresse oxidativo na patogênese da ND está bem estabelecido e genes pertencentes a vias pró- e antioxidantes são possíveis candidatos a conferirem susceptibilidade genética a essa e a outras complicações crônicas. Além do estresse oxidativo, o transporte intracelular de glicose, mediado por transportadores específicos, também parece exercer influência sobre a ND e outras complicações. O objetivo deste trabalho foi avaliar a associação entre ND e alguns polimorfismos de um único nucleotídeo (SNPs) em genes que codificam proteínas transportadoras de glicose (GLUT2 [SLC2A2]), proteínas pró-oxidantes (p22phox [CYBA] e NOX-2 [CYBB]) e proteínas antioxidantes (glutationa peroxidase-4 [GPX4] e catalase [CAT]) em uma coorte brasileira (n=453; 45,8% de pacientes com ND) e três coortes francesas (SURGENE [n=340; 17,7% de pacientes com ND na fase basal], GENEDIAB [n=313; 66,7% de pacientes com ND] e GENESIS [n=636; 49,7% de pacientes com ND]) de pacientes portadores de DM tipo 1. Os SNPs foram genotipados com o uso da técnica de reação em cadeia da polimerase (PCR) em tempo real e os resultados expressos em odds ratio (OR) ou hazard ratio (HR), com seus respectivos intervalos de confiança (IC), determinados em modelos ajustados de regressão logística politômica ou regressão de risco proporcional de Cox, respectivamente. A razão albumina/creatinina urinária (ACR) ou a taxa de excreção urinária de albumina (EUA) foram utilizadas para definir os estágios de ND e os pacientes foram classificados de acordo com a presença ou ausência de ND incipiente (ACR 30 - 300 mg/g de creatinina ou EUA 20 - 200 ?g/min ou 20 - 200 mg/L) e creatinina plasmática <1,7 mg/dL), ND estabilizada (ACR >300 mg/g de creatinina ou EUA > 200 ug/min ou > 200 mg/L e creatinina plasmática < 1,7 mg/dL ) ou ND avançada (ACR > 300 mg/g de creatinina ou EUA > 200 ug/min ou > 200 mg/L e creatinina plasmática > 1,7 mg/dL ou qualquer terapia de reposição renal) e também foram avaliadas associações dos SNPs com a taxa de filtração glomerular estimada (TFGe). O alelo raro A do SNP rs6610650 no gene CYBB foi associado com valores baixos de TFGe em mulheres na coorte brasileira e com a prevalência de ND estabilizada/avançada em mulheres da coorte francesa (OR 1,75; IC 95% 1,11 - 2,78; p=0,016). O alelo raro T do SNP rs713041 no gene GPX4 foi inversamente associado com a prevalência de ND estabilizada/avançada em homens na coorte brasileira (OR 0,30, IC95% 0,13 - 0,68, p=0,004) e com valores elevados de TFGe em homens na coorte francesa. O alelo raro A do SNP rs7947841 no gene CAT foi associado com a prevalência de ND incipiente (OR 2,79; IC95% 1,21 - 6,24; p=0,01) e ND estabilizada/avançada (OR 5,72; IC95% 1,62 - 22,03; p=0,007), bem como com a incidência de eventos renais, definidos como novos casos de microalbuminúria ou progressão para um estágio mais grave de ND durante o seguimento de estudo, na coorte SURGENE (HR 1,82; IC95% 1,13 - 2,81; p=0,01). O mesmo alelo de risco associou-se com a prevalência de ND incipiente (OR 3,13; IC95% 1,42 - 7,24; p=0,004) e com a incidência de insuficiência renal crônica terminal (IRCT) na coorte GENEDIAB (HR 2,11; IC95% 1,23 - 3,60; p=0,008) e com a prevalência de ND incipiente (OR 2,16; IC95% 1,14 - 4,10, p=0,02) e ND estabilizada/avançada (OR 2,71; IC95% 1,38 - 5,42; p=0,004) na coorte brasileira. O alelo raro T do SNP rs9932581 no gene CYBA foi inversamente associado com a prevalência de ND estabilizada/avançada (OR 0,60; IC95% 0,46 - 0,78; p=0,0001) e com valores mais baixos de TFGe nos pacientes de descendência europeia da coorte GENESIS/GENEDIAB. Este mesmo alelo foi associado com a incidência de eventos renais e de IRCT nas coortes SURGENE (HR 0,63; IC95% 0,46 - 0,86; p=0,003) e GENESIS/GENEDIAB (HR 0,51; IC95% 0,31 - 0,78; p=0,002), respectivamente. Entretanto estes resultados não foram replicados na coorte brasileira. O alelo raro T do SNP rs11924032 no gene SLC2A2 foi inversamente associado com a perda da TFGe ao logo do tempo (0,02%/ano vs 2,18%/ano para os pacientes portadores do genótipo GG; p=0,005), na coorte SURGENE. Este mesmo alelo foi inversamente associado com a incidência de IRCT nas coortes GENESIS/GENEDIAB (HR 0,53; IC95% 0,29 - 0,89; p=0,01). Os resultados observados para o gene SLC2A2 não forneceram fortes indícios para afirmarmos que este gene exerça um papel relevante no desenvolvimento da ND nos pacientes com DM tipo 1 nas coortes francesas estudadas. Em contrapartida, os SNPs nos genes que codificam as proteínas pró-oxidantes CYBA e CYBB e as proteínas antioxidantes GPX-4 e CAT foram capazes de modular o risco para doença renal em pacientes portadores de DM tipo 1, sendo que os SNPs presentes nos genes CYBB, GPX4 e CAT tiveram seus resultados replicados em coortes independentes, o que corrobora a importância destes genes e, consequentemente, do estresse oxidativo, na patogênese da ND / Diabetic nephropathy (DN) is a major cause of chronic nephropathy, with diabetes mellitus (DM) accounting for 44% of the prevalence of chronic kidney disease (CKD) in the world. The role of oxidative stress in the pathogenesis of DN is well established and genes belonging to pro- and antioxidant pathways are possible candidates to confer genetic susceptibility to this and other chronic complications. Besides oxidative stress, intracellular glucose transport mediated by specific transporters, also appears to influence DN and other complications. The aim of this study was to evaluate the association between DN and some single nucleotide polymorphisms (SNPs) present in genes encoding glucose transport proteins (GLUT2 [SLC2A2]), pro- (p22phox [CYBA] and NOX-2 [CYBB]) and antioxidants (glutathione peroxidase-4 [GPX4] and catalase [CAT]) proteins, in a Brazilian cohort [n= 453; 45.8% f patients with DN], and three French cohorts (SURGENE [n=340; 17.7% of patients with DN at baseline], GENEDIAB [n=313; 66.7% of patients with DN], and GENESIS [n=636; 49.7% of patients with DN]) of patients with type 1 DM. The SNPs were genotyped using the technique of real time polymerase chain reaction (PCR) and results expressed as odds ratio (OR) and hazard ratio (HR), with their respectively 95% confidence intervals (CI), determined by adjusted models of polytomic logistic regression and Cox proportional hazard regression, respectively. The albumin/creatinine ratio (ACR) or the urinary albumin excretion (UAE) rate were used to define the DN stages and the patients were classified according to the presence or absence of incipient DN (ACR 30 - 300 mg/g of creatinine or UAE 20 - 200 ug/min or 20 - 200 mg/L) and plasmatic creatinine < 1,7 mg/dL), established DN (ACR > 300 mg/g of creatinine or EUA > 200 ug/min or > 200 mg/L and plasmatic creatinine <1,7 mg/dL) or advanced DN (ACR >300 mg/g of creatinine or UAE > 200 ug/min or > 200 mg/L and plasmatic creatinine > 1,7 mg/dL or any renal replacement therapy). Associations for the estimated glomerular filtration rate (eGFR) were also evaluated. The rare allele A of the SNP rs6610650 in CYBB gene was associated with low values of eGFR in women in the Brazilian cohort and with the prevalence of established/advanced DN in women in the French cohort (OR 1.75, 95%CI 1.11 - 2.78, p=0.016). The rare allele T of the SNP rs713041 in GPX4 gene was inversely associated with the prevalence of established/advanced DN in men in the Brazilian cohort (OR 0.30, 95%CI 0.13 - 0.68, p=0.004) and with higher values of eGFR in men in the French cohort. The rare allele A of the SNP rs7947841 in CAT gene was associated with the prevalence of incipient DN (OR 2.79, 95%CI 1.21 - 6.24, p=0.01) and established/advanced DN (OR 5.72; 95%CI 1.62 - 22.03, p=0.007) as well as the incidence of renal events, defined as new cases of microalbuminuria or progression to a more severe stage during the follow-up study, in SURGENE cohort (HR 1.82, 95%CI 1.13 - 2.81, p=0.01). The same risk allele was associated with the prevalence of incipient DN (OR 3.13, 95%CI 1.42 - 7.24, p=0.004), the incidence of end-stage renal disease (ESRD) in the cohort GENEDIAB (HR 2.11, 95%CI 1.23 - 3.60, p=0.008) and with the prevalence of incipient DN (OR 2.16, 95%CI 1.14 - 4.10, p=0.02) and established/advanced DN (OR 2.71, 95%CI 1.38 - 5.42, p=0.004) in the Brazilian cohort. The rare T allele of the SNP rs9932581 in CYBA gene was inversely associated with the prevalence of established/advanced DN (OR: 0.60, 95%CI: 0.46 - .78, p=0.0001) and associated with lower values of eGFR in patients of GENESIS/GENEDIAB cohort. The same allele was inversely associated with the incidence of renal events and ESRD in SURGENE (HR 0.63, 95%CI 0.46 - 0.86, p=0.003) and GENESIS/GENEDIAB (HR 0.51, 95%CI 0.31 - 0.78, p=0.002) cohorts. However, these results were not replicated in the Brazilian cohort. The rare T allele of the SNP rs11924032 in SLC2A2 gene was inversely associated with the loss of eGFR during the follow-up (0.02%/year vs. 2.18%/year for patients with the GG genotype, p=0.005) in the SURGENE cohort. The same allele was inversely associated with the incidence of ESRD in the GENESIS/GENEDIAB cohorts (HR 0.53, 95%CI 0.29 - 0.89, p=0.01). The results observed for the SLC2A2 gene, in this study, did not provide strong evidence to state that this gene exerts a relevant role in the development of DN in patients with type 1 DM in the studied cohorts. However, SNPs in genes encoding the pro-oxidant proteins CYBA and CYBB, and the antioxidants proteins GPX-4 and CAT were able to modulate the risk of renal disease in patients with type 1 DM. The studied SNPs in CYBB, GPX4 and CAT genes had their results replicated in independent cohorts, which confirms the importance of these genes and, hence, of the oxidative stress in the pathogenesis of DN

Introdução: As neuropatias periférica (NP) e autonômica cardiovascular (NAC) são complicações prevalentes do diabetes mellitus (DM). Há indícios de que seu desenvolvimento se deve não somente ao controle metabólico. Neste sentido, a busca por preditores genéticos faz-se imperativa. Diversos genes relacionados às vias bioquímicas que levam ao dano celular induzido pela hiperglicemia têm sido investigados, destacando-se os genes relacionados às vias do extresse oxidativo. O balanço entre os sistemas antioxidantes (como glutationa e tiorredoxina) e pró-oxidantes (como o NADPH-oxidase) é um importante fator na defesa celular contra o estresse oxidativo. Objetivo primário: avaliar a associação entre os polimorfismos de um único nucleotídeo (SNP) pertencentes às vias anti- e pró-oxidantes mencionadas e a NP e NAC em pacientes DM tipo 1: 718C/T na região 3\' UTR (untranslated region) (rs713041) no gene da glutationa peroxidase 4 (GPX4); -129 C/T (rs1788390) no gene da glutamato cisteína ligase (GLCL); -1365 C/T (rs7211) no gene da proteína de interação com a tiorredoxina (TXNIP); -2810 A/G (rs6610650) no gene do CYBB; - 675 T/A (não registrado) no gene do CYBA. Objetivo secundário: avaliar a relação entre as diferentes complicações microvasculares entre si (neuropatia, doença renal diabética [DRD] e retinopatia diabética [RD]). Material e métodos: foram selecionados 378 pacientes com DM tipo 1 do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo e do Hospital das Clínicas da Universidade Estadual de Campinas com mais de 10 anos de doença e controle inadequado (HbA1c >8% em algum período da vida), e examinados para NP e NAC. A genotipagem dos polimorfismos foi realizada pela técnica de reação em cadeia da polimerase em tempo real (Sistema Taqman ®). Foram avaliadas variáveis clínicas, laboratoriais do metabolismo glicêmico e lipídico e a presença de DRD e de RD. Foram avaliados 257 pacientes retrospectivamente quanto à evolução da taxa de filtração glomerular estimada (TFGe) em relação à NP e NAC. O teste de Pearson foi usado para comparar as frequências dos genótipos e a magnitude de associação foi estimada pelo cálculo do odds ratios (OR), com respectivo intervalo de confiança (IC) ajustada por regressão logística para possíveis fatores de confusão. Resultados: A presença de pelo menos um alelo T do SNP +718C/T no gene GPX4 conferiu proteção para NAC (OR=0,39; IC 95% 0,17 - 0,84; P = 0,0165). Na análise de associação entre as complicações, observou-se que: (1) na presença de NP há aumento na probabilidade de NAC (OR = 3,38; IC95% 2,01 - 5,73; P < 0,0001), de albuminúria A3 (OR = 7,17; IC95% 3,68 - 14,53; P < 0,0001) e de RD proliferativa (OR = 9,58; IC95% 5,04 - 19,09; P < 0,0001) e (2) na presença de NAC há aumento na probabilidade de NP (OR = 3,72; IC95% 2,14 - 6,53; P < 0,0001), de albuminuria A3 (OR = 9,37; IC95% 4,68 - 19,65; P < 0,0001) e de RD proliferativa (OR = 3,30; IC95% 1,81 - 6,18, P < 0,0001). No subgrupo avaliado retrospectivamente, a presença de NP e de NAC associou-se com queda de TFGe anual maior (-4,74 mL/min/ano vs. -1,22 mL/min/ano; P < 0,0001 e -3,74 mL/min/ano vs. -1,54 mL/min/ano; P = 0,04, respectivamente). Conclusões: (1) a presença do alelo T no SNP +718C/T (rs713041) no gene GPX4 confere proteção para NAC na população com DM tipo 1 estudada e (2) existe associação de risco para NP e NAC entre si e para as formas graves de DRD e RD / Introduction: Peripheral (PN) and cardiovascular autonomic neuropathies (CAN) are prevalent complications of diabetes mellitus (DM). There are indications that their development occurs not only secondary to metabolic control. Thus, search for genetic predictors is very important. Several genes related to the biochemical pathways that lead to cellular damage induced by hyperglycemia have been investigated, emphasizing the genes related to the pathways of oxidative stress. The balance between antioxidant systems (such as glutathione and thioredoxin) and pro-oxidants (such as NADPH oxidase) is an important factor in cell defense against oxidative stress. Primary objective: to evaluate the association between the single nucleotide polymorphisms (SNP) of the mentioned anti-and pro-oxidant pathways and NP and NAC in type 1 DM patients: 718C / T in the 3 \'UTR (untranslated region) (rs713041) of the glutathione peroxidase 4 gene (GPX4); -129 C / T (rs1788390) in the glutamate cysteine ligase gene (GLCL); -1365 C / T (rs7211) in the thioredoxin interaction protein gene (TXNIP); -2810 A / G (rs6610650) in the CYBB gene; - 675 T / A (unregistered) in the CYBA gene. Secondary objective: to evaluate the relationship between different microvascular complications (neuropathy, diabetic renal disease [DRD] and diabetic retinopathy [DR]). Material and methods: 378 type 1 patients DM were selected from the Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo and from Hospital das Clínicas da Universidade Estadual de Campinas; they had more than 10 years of disease and inadequate control (HbA1c > 8% at some period of life), and were examined for NP and NAC. Polymorphism genotyping was performed by real-time polymerase chain reaction (Taqman System®). Clinical, glycemic and lipid metabolism laboratorial variables and the presence of DRD and DR were evaluated. Also 257 patients were retrospectively evaluated regarding the evolution of the estimated glomerular filtration rate (eGFR) in relation to PN and CAN. The Pearson test was used to compare the frequencies of the genotypes and the magnitude of association was estimated by the odds ratios (OR), with the respective confidence interval (CI) adjusted by logistic regression for possible confounding factors. Results: The presence of at least one T allele at the SNP + 718C / T of the GPX4 gene protected for CAN (OR = 0.39; 95% CI 0.17-0.84; P = 0.0165). In the analysis of the association between complications, it was observed that: (1) in the presence of NP, there was an increase in risk of NAC (OR = 3.38; 95% CI 2.01 - 5.73; P < 0.0001), of albuminuria A3 (OR = 7.17; 95% CI 3.68 - 14.53; P < 0.0001) and of proliferative DR (OR = 9.58; 95% CI, 5.04 - 19.09; P < 0.0001) (2) in the presence of CAN, there was an increase in risk of PN (OR = 3.72; 95% CI 2.14 - 6.53; P < 0.0001), albuminuria A3 (OR = 9.37; CI95% 4.68 - 19.65; P<0,0001) and proliferative DR (OR = 3.30; CI95% 1.81 - 6.18; P < 0,0001).) In the subgroup evaluated retrospectively, the presence of PN and CAN was associated with a greater annual decrease of eGFR (-4.74 mL / min / year vs. -1.22 mL / min / year, P < 0.0001 and - 3.74 mL / min / yr vs. -1.54 mL / min / yr, P < 0.04, respectively). Conclusions: (1) the presence of the T allele at the SNP + 718C / T (rs713041) in the GPX4 gene confers protection for the presence of CAN in the studied type 1 DM population and (2) there is a risk association for PN and CAN among themselves and for severe forms of DRD and RD

INTRODUÇÃO: acredita-se que o controle glicêmico inadequado, a duração do diabetes melito (DM) e a presença de hipertensão arterial e dislipidemia sejam os fatores de risco mais importantes para o desenvolvimento das complicações microvasculares no DM, contudo, existem inúmeras evidências sugerindo que uma predisposição genética participe da suscetibilidade para o desenvolvimento dessas complicações. Vários genes relacionados aos mecanismos dos danos induzidos pela hiperglicemia têm sido investigados. O papel do estresse oxidativo na patogênese das complicações crônicas do DM vem sendo demonstrado e os genes que codificam enzimas que participam dos mecanismos antioxidantes são candidatos a conferirem suscetibilidade ou proteção contra as complicações crônicas. A glutationa é um dos mais importantes antioxidantes endógenos; no entanto, a associação entre polimorfismos em genes que codificam enzimas que participam desse sistema e complicações crônicas do DM foi pouco explorada na literatura. OBJETIVOS: avaliar a associação de polimorfismos em três genes que codificam enzimas relacionadas ao metabolismo da glutationa com o desenvolvimento de nefropatia e retinopatia em pacientes diabéticos tipo 1. Foram estudados: o polimorfismo -129C/T do gene GCLC, o número de repetições do trinucleotídeo GCG no exon 1 do gene GPX1 e o polimorfismo -65T/C do gene GPX3. CASUÍSTICA E MÉTODOS: 299 pacientes (139 do gênero masculino e 160 do gênero feminino) com DM tipo 1 com mais de 15 anos de diagnóstico e mau controle glicêmico foram divididos conforme presença ou ausência das seguintes complicações: nefropatia diabética (ND) avançada, ND, doença renal crônica (DRC) estágios 3 a 5 e retinopatia diabética proliferativa (RDP). Em cada grupo foram avaliadas as freqüências das variantes alélicas dos três genes estudados. RESULTADOS: a distribuição dos genótipos na população estudada foi consistente com o equilíbrio de Hardy-Weinberg para os três genes analisados. A presença de pelo menos um alelo T do polimorfismo -129C/T do gene GCLC conferiu risco independente para a presença de ND avançada (OR = 2,82 ; IC 95% = 1,13 - 7,05; p = 0,026), para ND (OR = 3,64; IC 95% = 1,27 10,36; p = 0,016) e para DRC estágios 3 a 5 (OR = 5,74; IC 95% = 2,17 15,1; p < 0,001) e a presença de pelo menos um alelo C do polimorfismo -65 T/C conferiu risco independente para a presença de ND avançada (OR = 2,62; IC 95% = 1,19 -5,72, p = 0,022) na população estudada. Não houve associação do número de repetições do trinucleotídeo GCG do gene GPX1 com nenhuma das complicações estudadas. O haplótipo CC_TT, composto pelos alelos selvagens dos genes GCLC e GPX3, foi negativamente associado com ND avançada (OR = 0,32, IC 95% = 0,15 0,66; p = 0,002) e DRC (OR = 0,25; IC 95% = 0,11 - 0,55; p = 0,001). CONCLUSÕES: a presença de pelo menos um alelo T do polimorfismo -129 C/T do gene GCLC e de pelo menos um alelo C do polimorfismo -65 T/C do gene GPX3, ambos associados a uma menor atividade transcricional do respectivo gene, conferiram risco para a presença de complicações renais na população de pacientes estudada. / INTRODUCTION: glycemic control, diabetes duration, systemic hypertension and dyslipidemia have been implicated as main risk factors for the development of diabetic microangiopathy, however there is evidence suggesting that genetic predisposition plays a role in the susceptibility to microvascular complications. Based on underlying pathogenesis, polymorphisms of several genes belonging to multiple pathways have been investigated, like the genes related to mechanisms of hyperglycemia-induced damage. The role of oxidative stress in the pathogenesis of diabetic complication has been increasingly demonstrated and genes coding enzymes involved in antioxidant defense are candidates to confer susceptibility or protection against these complications. Glutathione is one the most important endogen antioxidants, however, the association between polymorphisms in genes related to glutathione metabolism and diabetic complications has not been deeply investigated. OBJECTIVES: to study the association between polymorphisms in three genes which code enzymes related to glutathione metabolism and the development of nephropathy and retinopathy in type 1 diabetic patients: the polymorphism -129 C/T of GCLC, the number of trinucleotide GCG repeats at exon 1 of GPX1 and the polymorphism -65 T/C of GPX3. CASUISTIC AND METHODS: 299 type 1 diabetic patients (139 male and 160 female) with at least 15 years from diagnosis and poor glycemic control were studied. The patients were divided in two groups according to the presence or absence of diabetic complications: with and without diabetic nephropathy (DN), advanced DN, chronic kidney disease (CKD) stages 3 to 5 and proliferative diabetic retinopathy (PDR). RESULTS: The allelic distribution of the three studied polymorphisms was consistent with Hardy-Weinberg equilibrium. The presence of at least one T allele of GCLC 129 C/T was an independent risk factor for advanced DN (OR = 2.82 ; CI 95% = 1.13 -7.05; p = 0.026), for DN (OR = 3.64; CI 95% = 1.27 10.36; p = 0.016) and for CKD stages 3 to 5 (OR = 5.74; CI 95% = 2.17 15.1; p < 0.001) and the presence of at least one C allele of GPX3 -65 T/C was an independent risk factor for advanced DN (OR = 2.62; IC 95% = 1.19 -5.72, p = 0.022) in the studied population. There were no associations between GCG trinucleotide repeats of GPX1 and diabetic complications. The haplotype CC_TT, composed by GCLC and GPX3 wild type alleles, was negatively related to advanced DN (OR = 0.32, CI 95% = 0.15 0.66; p = 0.002) and CKD (OR = 0.25; CI 95% = 0.11 0.55; p = 0.001). CONCLUSIONS: the presence of at least one T allele of -129C/T polymorphism of GCLC and one C allele of -65 T/C polymorphism of GPX3, both associated to a lower transcriptional activity of its genes, conferred risk for renal complications in the studied population.

INTRODUÇÃO: A retinopatia diabética (RD) é uma das complicações mais frequentes dos diabetes mellitus tipo 1 (DM1). Durante a hiperglicemia, as células endoteliais da retina são expostas a altas concentrações de glicose e são incapazes de conter seu influxo. Isso resulta na ativação de vias deletérias intracelulares que culminam com o aumento de espécies reativas de oxigênio (ROS) e lesão neuronal e vascular. O estado pró inflamatório e pró trombótico ativa vias pró-oxidantes como a da NADPH oxidase. O excesso de ROS não é devidamente tamponado pelas vias antioxidantes (tais como as vias da glutationa e da tiorredoxina) em situações de hiperglicemia crônica, o que contribui para perpetuar o dano. OBJETIVO: Caracterizar uma população de pacientes DM1 quanto ao grau de RD e analisar a associação desta complicação microvascular com cinco polimorfismo de um único nucleotídeo (SNP) em genes pertencentes a vias pró- e antioxidantes. MÉTODOS: Pacientes acompanhados no ambulatório de diabetes de dois hospitais terciários do estado de São Paulo foram submetidos a fotos digitais do fundo de olho que incluíam os sete campos padronizados no estudo Early Treatment Diabetic Retinopathy Study (ETDRS) ou a uma oftalmoscopia binocular indireta; ambos foram avaliados por um único oftalmologista em cada um dos hospitais. A genotipagem dos SNPs foi feita por reação em cadeia de polimerase após transcrição reversa com duas sondas marcadas para cada reação. Os seguintes SNPs foram estudados: rs713041 (gene GPX4), rs17883901 (gene GCLC), rs6610650 (gene CYBB), -675 T/A (gene CYBA) e rs7211 (gene TXNIP). Os dados clínicos foram coletados por consulta ao prontuário médico ou questionário. Foi utilizado o modelo de regressão logística nominal politômica, tendo como categoria de referência a ausência de RD (ARD) ou dicotômica, tendo como categorias de referência a ausência de RD proliferativa (RDP) ou ARD. Após correção de Bonferroni, um valor de p <= 0,02 foi considerado significante. RESULTADOS: Um total de 341 pacientes (62% mulheres; idade média de 35 [±11] anos; com 22 [±9] anos de duração do DM1 e HbA1c de 8,6% [±1,6]) foi incluído. A prevalência de RDP foi de 30%, enquanto 42% dos pacientes apresentavam RD não proliferativa (RDNP). Somente os SNPs cuja distribuição dos genótipos respeitou o equilíbrio de Hardy-Weinberg foram analisados. Após ajuste para potenciais fatores de confusão, a presença do alelo T no SNP rs713041 (+718 C/T) no GPX4 foi inversamente associada à prevalência de RDP em pacientes do sexo feminino, com um odds ratio (OR) de 0,36 (intervalo de confiança [IC] de 95% de 0,17 a 0,75; p = 0,007) na análise dicotômica de RDP versus ausência de RDP. A presença do alelo T no SNP rs17883901 (-129 C/T) no GCLC conferiu risco para RDP na análise politômica (OR de 4,23; IC 95% de 1,38 a 12,93; p=0,01) e conferiu risco para a presença de qualquer grau de RD na análise dicotômica (ARD versus RDNP + RDP; OR de 3,07; IC 95% de 1,22 a 8,95; p=0,02). Não houve associação entre o SNP rs6610650 (gene CYBB) e RD nessa população. CONCLUSÃO: Os SNPs funcionais rs713041 no GPX4 e rs17883901 no GCLC modularam a susceptibilidade a RD na população de pacientes com DM1 estudada / INTRODUCTION: Diabetic retinopathy (DR) is one of the most frequent complications of type 1 diabetes mellitus (T1D). During hyperglycemia, retinal endothelial cells are exposed to high glucose concentrations and are unable to contain their influx. This results in the activation of deleterious intracellular pathways that culminate with the increase of reactive oxygen species (ROS) and neuronal and vascular injury. The pro-inflammatory and prothrombotic state activates pro-oxidant pathways such as NADPH oxidase. The excess of ROS is not adequately buffered by the antioxidant pathways (such as glutathione and thioredoxin pathways) in situations of chronic hyperglycemia, which contributes to perpetuate the damage. OBJECTIVE: To characterize a population of T1D patients regarding DR degree and to analyze the association of this microvascular complication with five single nucleotide polymorphisms (SNP) in genes belonging to pro- and antioxidant pathways. METHODS: Patients followed at the diabetes outpatient clinic of two tertiary hospitals in the state of São Paulo were submitted to digital photos of the eye fundus that included the seven fields standardized in the Early Treatment Diabetic Retinopathy Study (ETDRS) or to binocular indirect ophthalmoscopy; both were evaluated by a single ophthalmologist in each one of the hospitals. SNP genotyping was performed by polymerase chain reaction after reverse transcription with two labeled probes for each reaction. The following SNPs were studied: rs713041 (GPX4 gene), rs17883901 (GCLC gene), rs6610650 (CYBB gene), -675 T/A (CYBA gene) and rs7211 (TXNIP gene). The clinical data were collected by consulting the medical chart or by questionnaire. The polytomous nominal logistic regression model was used, having as reference category the absence of DR (ADR) or the dichotomous nominal logistic regression model was used, having as reference categories the absence of proliferative DR (PDR) or ADR. After Bonferroni correction, a p value <= 0.02 was considered significant. RESULTS: A total of 341 patients (62% female; mean age of 35 [± 11] years-old; diabetes duration of 22 [± 9] years and HbA1c of 8.6% [± 1.6]) was included. The prevalence of PDR was 30%, while 42% of the patients had non-proliferative DR (NPDR). Only SNPs whose distribution of genotypes respected the Hardy-Weinberg equilibrium were analyzed. After adjusting for potential confounding factors, the presence of the T allele at rs713041 (+718 C/T) in GPX4 was inversely associated with the prevalence of PDR in female patients, with an odds ratio (OR) of 0.36 (95% confidence interval [CI] 0.17-0.75; p = 0.007) in the dichotomous analysis of PDR versus absence of PDR. The presence of the T allele at rs17883901 (-129 C/T) in GCLC conferred risk for PDR in the polytomous analysis (OR of 4.23; 95% CI 1.38 to 12.93; p = 0.01) and for any degree of DR in the dichotomous analysis (ADR versus NPDR + PDR; OR of 3.07; 95% CI 1.22-8.95; p = 0.02). There was no association between the SNP rs6610650 (CYBB gene) and DR in this population. CONCLUSION: The functional SNPs rs713041 in GPX4 and rs17883901 in GCLC modulated the susceptibility to DR in the studied population of patients with T1D

Das 1817 erstmals schriftlich erwähnte Selen galt lange Zeit nur als toxisch und sogar als procancerogen, bis es 1957 von Schwarz und Foltz als essentielles Spurenelement erkannt wurde, dessen biologische Funktionen in Säugern durch Selenoproteine vermittelt werden. Die Familie der Glutathionperoxidasen nimmt hierbei eine wichtige Stellung ein. Für diese sind konkrete Funktionen und die dazugehörigen molekularen Mechanismen, welche über die von ihnen katalysierte Hydroperoxidreduktion und damit verbundene antioxidative Kapazität hinausgehen, bislang nur unzureichend beschrieben worden. <br><br> Die Funktion der gastrointestinalen Glutathionperoxidase (GI-GPx) wird als Barriere gegen eine Hydroperoxidabsorption im Gastrointestinaltrakt definiert. Neuen Erkenntnissen zufolge wird die GI-GPx aber auch in verschiedenen Tumoren verstärkt exprimiert, was weitere, bis dato unbekannte, Funktionen dieses Enzymes wahrscheinlich macht.<br> Um mögliche neue Funktionen der GI-GPx, vor allem während der Cancerogenese, abzuleiten, wurde hier die transkriptionale Regulation der GI-GPx detaillierter untersucht. Die Sequenzanalyse des humanen GI-GPx-Promotors ergab das Vorhandensein von zwei möglichen "antioxidant response elements" (ARE), bei welchen es sich um Erkennungssequenzen des Transkriptionsfaktors Nrf2 handelt. Die meisten der bekannten Nrf2-Zielgene gehören in die Gruppe der Phase-II-Enzyme und verfügen über antioxidative und/oder detoxifizierende Eigenschaften. Sowohl auf Promotorebene als auch auf mRNA- und Proteinebene konnte die Expression der GI-GPx durch typische, in der Nahrung enthaltene, Nrf2-Aktivatoren wie z.B. Sulforaphan oder Curcumin induziert werden. Eine direkte Beteiligung von Nrf2 wurde durch Cotransfektion von Nrf2 selbst bzw. von Keap1, das Nrf2 im Cytoplasma festhält, demonstriert. Somit konnte die GI-GPx eindeutig als Nrf2-Zielgen identifiziert werden. Ob sich die GI-GPx in die Gruppe der antiinflammatorischen und anticancerogenen Phase-II-Enzyme einordnen lässt, bleibt noch zu untersuchen. <br><br> Die Phospholipidhydroperoxid Glutathionperoxidase (PHGPx) nimmt aufgrund ihres breiten Substratspektrums, ihrer hohen Lipophilie und ihrer Fähigkeit, Thiole zu modifizieren, eine Sonderstellung innerhalb der Familie der Glutathionperoxidasen ein. Mit Hilfe eines PHGPx-überexprimierenden Zellmodells wurden deshalb Beeinflussungen des zellulären Redoxstatus und daraus resultierende Veränderungen in der Aktivität redoxsensitiver Transkriptionsfaktorsysteme und in der Expression atheroskleroserelevanter Adhäsionsmoleküle untersucht. Als Transkriptionsfaktoren wurden NF-kB und Nrf2 ausgewählt. Die Bindung von NF-kB an sein entsprechendes responsives Element in der DNA erfordert das Vorhandensein freier Thiole, wohingegen Nrf2 durch Thiolmodifikation von Keap1 freigesetzt wird und in den Kern transloziert. Eine erhöhte Aktivität der PHGPx resultierte in einer Erhöhung des Verhältnisses von GSH zu GSSG, andererseits aber in einer verminderten Markierbarkeit freier Proteinthiole. PHGPx-Überexpression reduzierte die IL-1-induzierte NF-kB-Aktivität, die sich in einer verminderten NF-kB-DNA-Bindefähigkeit und Transaktivierungsaktivität ausdrückte. Auch war die Proliferationsrate der Zellen vermindert. Die Expression des NF-kB-regulierten vaskulären Zelladhäsionsmoleküls, VCAM-1, war ebenfalls deutlich verringert. Umgekehrt war in PHGPx-überexprimierenden Zellen eine erhöhte Nrf2-Aktivität und Expression der Nrf2-abhängigen Hämoxygenase-1 zu verzeichnen. Letzte kann für die meisten der beobachteten Effekte verantwortlich gemacht werden.<br><br> Die hier dargestellten Ergebnisse verdeutlichen, dass eine Modifizierung von Proteinthiolen als wichtige Determinante für die Regulation der Expression und Funktion von Glutathionperoxidasen angesehen werden kann. Entgegen früheren Vermutungen, welche oxidative Vorgänge generell mit pathologischen Veränderungen assoziierten, scheint ein moderater oxidativer Stress, bedingt durch eine transiente Thiolmodifikation, durchaus günstige Auswirkungen zu haben, da, wie hier dargelegt, verschiedene, miteinander interagierende, cytoprotektive Mechanismen ausgelöst werden. Hieran wird deutlich, dass sich "antioxidative Wirkung" oder "oxidativer Stress" keineswegs nur auf "gute" oder "schlechte" Vorgänge beschränken lassen, sondern im Zusammenhang mit den beeinflussten (patho)physiologischen Prozessen und dem Ausmaß der "Störung" des physiologischen Redoxgleichgewichtes betrachtet werden müssen. / Selenium was discovered in 1817 by the Swedish chemist Berzelius and was for a long time considered as being toxic and even procarcinogenic. In 1957, however, Schwarz and Foltz realized that selenium is an essential trace element which elicits its biological functions in mammals as a structural component of selenoproteins among which the family of glutathione peroxidases plays a dominant role. Glutathione peroxidases reduce hydroperoxides to the corresponding alcohols and contribute to the antioxidative capacity of a cell. However, other functions of glutathione peroxidases and the according molecular mechanisms have hardly been described.>br><br> The gastrointestinal glutathione peroxidase (GI-GPx) is believed to build a barrier against the absorption of foodborne hydroperoxides. In addition, GI-GPx expression is increased in different tumors. This indicates further, still unknown, functions of this enzyme.<br> In order to elucidate new possible functions of GI-GPx, especially during carcinogenesis, the transcriptional regulation of GI-GPx was analyzed in more detail. An analysis of the GI-GPx promoter sequence revealed the presence of two putative "antioxidant response elements" (ARE) which are recognition sites for the transcription factor Nrf2. Most of the known Nrf2 target genes either belong to the group of phase-II detoxification enzymes or possess antioxidative and/or detoxifying properties. On promoter level as well as on mRNA- and protein level the expression of GI-GPx was induced by typical Nrf2-activating compounds such as sulforaphane or curcumin that are contained in the diet. A direct involvement of Nrf2 was demonstrated by cotransfection of Nrf2 itself or by cotransfection of Keap1 which retains Nrf2 in the cytosol. Thus, the GI-GPx gene was unequivocally identified as a new target for Nrf2. Whether GI-GPx also belongs in the category of antiinflammatory and anticarcinogenic enzymes remains to be elucidated.<br><br> The phospholipid hydroperoxide glutathione peroxidase (PHGPx) is exceptional among the glutathione peroxidases because of its broad range of substrates, its high lipophilicity, and its ability to modify protein thiols. With PHGPx-overexpressing cells, the influence of PHGPx on the cellular redox state and on resulting changes in the activity of redox-sensitive transcription factors and on the expression of proatherogenic adhesion molecules was analyzed. For this, the redox-sensitive transcription factors NF-kB and Nrf2 were chosen. NF-kB requires free thiols for being able to bind to its responsive element within the DNA, whereas Nrf2 is released from Keap1 and translocates to the nucleus upon a modification of protein thiols. PHGPx-overexpression resulted in an increase in the ratio of GSH to GSSG, in a reduced amount of intracellular protein thiols, and in a diminished proliferation rate. Furthermore, PHGPx-overexpressing cells displayed a reduced IL-1-dependent NF-kB activity as was assessed by a reduced NF-kB DNA-binding ability and activity of a NF-kB-driven reporter gene. In addition, the expression of the NF-kB-dependent vascular cell adhesion molecule (VCAM-1) was also inhibited by overexpression of PHGPx. On the other hand, PHGPx-overexpressing cells displayed an increased activity of Nrf2 that was accompanied by an increased expression of the Nrf2-dependent heme oxygenase-1. Heme oxygenase-1 most likely is responsible for most of the aforementioned effects.<br><br> The data presented here show that a modification of protein thiols can be regarded as an important determinant for the regulation and for the functions of glutathione peroxidases. In contrast to the previous assumption that oxidative processes are always linked to pathologic changes, a moderate oxidative stress seems to have beneficial effects, because it triggers different cytoprotective mechanisms. It can be concluded that the terms "antioxidative effect" or "oxidative stress" cannot simply be restricted to "good" or "bad" processes, but need to be seen in context with the modulated (patho)physiological processes and the degree of "disturbance" of the physiologic redox balance.