Noncanonical and reversible cysteine ubiquitination prevents the overubiquitination of PEX5 at the peroxisomal membrane.

PEX5, the peroxisomal protein shuttling receptor, binds newly synthesized proteins in the cytosol and transports them to the organelle. During its stay at the peroxisomal protein translocon, PEX5 is monoubiquitinated at its cysteine 11 residue, a mandatory modification for its subsequent ATP-dependent extraction back into the cytosol. The reason why a cysteine and not a lysine residue is the ubiquitin acceptor is unknown. Using an established rat liver-based cell-free in vitro system, we found that, in contrast to wild-type PEX5, a PEX5 protein possessing a lysine at position 11 is polyubiquitinated at the peroxisomal membrane, a modification that negatively interferes with the extraction process. Wild-type PEX5 cannot retain a polyubiquitin chain because ubiquitination at cysteine 11 is a reversible reaction, with the E2-mediated deubiquitination step presenting faster kinetics than PEX5 polyubiquitination. We propose that the reversible nonconventional ubiquitination of PEX5 ensures that neither the peroxisomal protein translocon becomes obstructed with polyubiquitinated PEX5 nor is PEX5 targeted for proteasomal degradation.

Comparative analysis of antioxidant and fatty acid composition in avocado (Persea americana Mill.) fruits: Exploring regional and commercial varieties.

On Madeira Island, Portugal, the avocado crop benefits from a Mediterranean climate, exhibiting exceptional phytochemical and biochemical properties. Aiming to evaluate the antioxidant quality and fatty acid composition with a commercial avocado, flours were obtained from five varieties (four regional and one commercial Hass) across different tissues (pulp and by-products) and cycles (years and on-tree maturation stages). Results showed that a regional variety with thin purple skin had the highest antioxidant qualities and lipid content, surpassing the other regional and commercial Hass varieties. Oleic acid prevailed in all samples, with regional avocados containing arachidonic acid which is an uncommon occurrence among higher plants. Variations in fatty acid content were influenced by the timing of harvest. These outcomes highlight the promising potential of avocados from Madeira Island.

Glutathione and peroxisome redox homeostasis.

Despite intensive research on peroxisome biochemistry, the role of glutathione in peroxisomal redox homeostasis has remained a matter of speculation for many years, and only recently has this issue started to be experimentally addressed. Here, we summarize and compare data from several organisms on the peroxisome-glutathione topic. It is clear from this comparison that the repertoire of glutathione-utilizing enzymes in peroxisomes of different organisms varies widely. In addition, the available data suggest that the kinetic connectivity between the cytosolic and peroxisomal pools of glutathione may also be different in different organisms, with some possessing a peroxisomal membrane that is promptly permeable to glutathione whereas in others this may not be the case. However, regardless of the differences, the picture that emerges from all these data is that glutathione is a crucial component of the antioxidative system that operates inside peroxisomes in all organisms.

The mammalian peroxisomal membrane is permeable to both GSH and GSSG - Implications for intraperoxisomal redox homeostasis.

Despite the large amounts of H2O2 generated in mammalian peroxisomes, cysteine residues of intraperoxisomal proteins are maintained in a reduced state. The biochemistry behind this phenomenon remains unexplored, and simple questions such as "is the peroxisomal membrane permeable to glutathione?" or "is there a thiol-disulfide oxidoreductase in the organelle matrix?" still have no answer. We used a cell-free in vitro system to equip rat liver peroxisomes with a glutathione redox sensor. The organelles were then incubated with glutathione solutions of different redox potentials and the oxidation/reduction kinetics of the redox sensor was monitored. The data suggest that the mammalian peroxisomal membrane is promptly permeable to both reduced and oxidized glutathione. No evidence for the presence of a robust thiol-disulfide oxidoreductase in the peroxisomal matrix could be found. Also, prolonged incubation of organelle suspensions with glutaredoxin 1 did not result in the internalization of the enzyme. To explore a potential role of glutathione in intraperoxisomal redox homeostasis we performed kinetic simulations. The results suggest that even in the absence of a glutaredoxin, glutathione is more important in protecting cysteine residues of matrix proteins from oxidation by H2O2 than peroxisomal catalase itself.

The Extraction Mechanism of Monoubiquitinated PEX5 from the Peroxisomal Membrane.

The AAA ATPases PEX1•PEX6 extract PEX5, the peroxisomal protein shuttling receptor, from the peroxisomal membrane so that a new protein transport cycle can start. Extraction requires ubiquitination of PEX5 at residue 11 and involves a threading mechanism, but how exactly this occurs is unclear. We used a cell-free in vitro system and a variety of engineered PEX5 and ubiquitin molecules to challenge the extraction machinery. We show that PEX5 modified with a single ubiquitin is a substrate for extraction and extend previous findings proposing that neither the N- nor the C-terminus of PEX5 are required for extraction. Chimeric PEX5 molecules possessing a branched polypeptide structure at their C-terminal domains can still be extracted from the peroxisomal membrane thus suggesting that the extraction machinery can thread more than one polypeptide chain simultaneously. Importantly, we found that the PEX5-linked monoubiquitin is unfolded at a pre-extraction stage and, accordingly, an intra-molecularly cross-linked ubiquitin blocked extraction when conjugated to residue 11 of PEX5. Collectively, our data suggest that the PEX5-linked monoubiquitin is the extraction initiator and that the complete ubiquitin-PEX5 conjugate is threaded by PEX1•PEX6.

Statin Therapy Among Bariatric Patients: The Impact on Metabolic Outcomes and Diabetes Status.

INTRODUCTION: Statin therapy is associated with an increased risk of developing diabetes. Among bariatric patients, the influence of this therapy on various metabolic outcomes, such as diabetes status and its remission, is largely unknown. METHODS: This was a retrospective study of 1710 patients who underwent bariatric surgery at our hospital between January/2010 and June/2017. We compared patients with and without statin therapy at baseline, 12 and 24 months after surgery regarding statin use and its impact on several clinical and analytical parameters. Multiple linear regression was performed, adjusting differences for age, sex, surgery type, antidiabetic drugs at baseline, hypertension at baseline, LDL cholesterol ˃ 130 mg/dL, weight variation one year after surgery, and age of obesity onset. RESULTS: The overall prevalence of statin use was 20.2% before, 13.6% 12 months after surgery, and 15.0% 24 months after surgery. There was a larger reduction in fasting glucose and HbA1c at 12 and 24 months after surgery among statin-treated patients, with the opposite trend for weight reduction and BMI. Statin-treated patients with diabetes had lower diabetes remission rates (45.3 vs 68.5%) 12 months after surgery, with the highest reduction in HbA1c (1.3±1.3 vs -1.1±1.2%; p=0.042), fasting glucose (-40.8±48.8 vs -30.9±41.6 mg/dL; p=0.028), and insulin (-21.7±28.2 vs -13.4±14.2 mIU/L; p=0.039). The proportion of new-onset cases of diabetes was equal between statin-treated vs non-treated individuals at 12 months (1.9%) and 24 months (1.0%) after surgery. CONCLUSION: Bariatric surgery seems to lead to diabetes remission more frequently in patients not treated with statins. A larger reduction was observed in fasting glucose and HbA1c among statin-treated patients. Statin did not contribute to an increased proportion of new-onset diabetes after surgery.

Male gender as a poor prognostic factor in Medullary Thyroid Carcinoma: behaviour or biological difference?

PURPOSE: Due to the low incidence and heterogeneous behaviour of medullary thyroid carcinoma (MTC), its prognostic factors are still not well stablished. While several large studies have investigated the impact of gender in differentiated thyroid cancer (DTC), its role in MTC outcomes remains controversial. We aim to identify MTC prognostic features, specially focusing on the role of gender. METHODS: Retrospective analysis of 76 patients diagnosed with MTC between 1984 and 2018 at a Portuguese Comprehensive Cancer Center. RESULTS: Patients presented a median age at diagnosis of 49 years and multiple endocrine neoplasia type 2 (MEN2) was identified in 27.6% of them, with those individuals being significantly younger (P<0.001). Most cases were diagnosed as stage IV disease (46.9%), except for the subgroup detected through pre-symptomatic genetic screening (55.6% at stage I). The 5- and 10-year survival rates were 87.6% and 75.6%, respectively. Univariate analysis identified male gender (P=0.010), age ≥45 years (P=0.007), presence of distant metastasis at diagnosis (P<0.01), capsule invasion (P=0.004), extrathyroidal invasion (P=0.003) and absence of biochemical cure after surgery (P=0.042) as having a negative impact on prognosis. On multivariate analysis, male gender (P=0.046) remained an independent predictor of mortality, as well as an older age (P<0.001) and the presence of distant metastases (P=0.012). CONCLUSIONS: Male gender independently predicted worse survival in MTC patients even after adjusting for age and disease stage. The few older studies on the topic pointed to a behavioural explanation regarding medical care seeking patterns by men, but our study and newer genetic and basic-science oriented publications raise the possibility of a true biological difference between genders in the tumourigenesis of MTC that should me further investigated.

Secondary Hyperparathyroidism Among Bariatric Patients: Unraveling the Prevalence of an Overlooked Foe.

INTRODUCTION: Bariatric surgery (BS) is the most effective therapeutic approach to obesity. It is associated with great gastrointestinal anatomic changes, predisposing the patients to altered nutrient absorption that impacts phosphocalcium metabolism. This study aimed to clarify the prevalence of secondary hyperparathyroidism (SHPT) and its predictors in patients submitted to BS. METHODS: Retrospective study of 1431 patients who underwent metabolic surgery between January 2010 and June 2017 and who were followed for at least 1 year. We compared the clinical and biochemical characteristics of patients with and without secondary hyperparathyroidism (considering SHPT a PTH ˃ 69 pg/mL). Two different analyses were performed: (1) paired analysis of participants before and 1 year after surgery (N = 441); (2) Cross sectional analysis of participants submitted to bariatric surgery before (N = 441), 1 year after (N = 1431) and 4 years after surgery (N = 333). Multiple logistic regression models were used to evaluate possible predictors of SHPT after BS. RESULTS: The overall prevalence of SHPT was 24.9% before surgery, 11.2% 1 year after surgery and 21.3% 4 years after surgery. Patients submitted to LAGB had the highest prevalence of SHPT 1 year after surgery (19.4%; vs RYGB, 12.8%, vs SG, 5.3%). Four years after surgery, RYGB had the highest prevalence of SHPT (27.0%), followed by LAGB (13.2%) and SG (6.9%). Higher body mass index and age, decreased levels of vitamin D and RYGB seem to be independent predictors of SHPT 1 year after surgery. The only independent predictor of SHPT 4 years after surgery was RYGB. CONCLUSION: The prevalence of SHPT is higher before and 4 years after BS than 1 year after surgery. This fact raises some questions about the efficacy of the implemented follow-up plans of vitamin D supplementation on the long term, mainly among patients submitted to RYGB.

Membrane topologies of PEX13 and PEX14 provide new insights on the mechanism of protein import into peroxisomes.

PEX13 and PEX14 are two core components of the so-called peroxisomal docking/translocation module, the transmembrane hydrophilic channel through which newly synthesized peroxisomal proteins are translocated into the organelle matrix. The two proteins interact with each other and with PEX5, the peroxisomal matrix protein shuttling receptor, through relatively well characterized domains. However, the topologies of these membrane proteins are still poorly defined. Here, we subjected proteoliposomes containing PEX13 or PEX14 and purified rat liver peroxisomes to protease-protection assays and analyzed the protected protein fragments by mass spectrometry, Edman degradation and western blotting using antibodies directed to specific domains of the proteins. Our results indicate that PEX14 is a bona fide intrinsic membrane protein with a Nin -Cout topology, and that PEX13 adopts a Nout -Cin topology, thus exposing its carboxy-terminal Src homology 3 [SH3] domain into the organelle matrix. These results reconcile several enigmatic findings previously reported on PEX13 and PEX14 and provide new insights into the organization of the peroxisomal protein import machinery. ENZYMES: Trypsin, EC3.4.21.4; Proteinase K, EC3.4.21.64; Tobacco etch virus protease, EC3.4.22.44.

Pressão diastólica final do ventrículo esquerdo e síndromes coronarianas agudas / Left ventricular end diastolic pressure and acute coronary syndromes / Presión diastólica final del ventrículo izquierdo y síndromes coronarios agudos

FUNDAMENTO: Há falta de dados sobre o impacto prognóstico da pressão diastólica final do ventrículo esquerdo (PDFVE) sobre as síndromes coronarianas agudas (SCA). OBJETIVO: Avaliar a PDFVE e suas implicações prognósticas em pacientes com SCA. MÉTODOS: Estudo prospectivo, longitudinal e contínuo de 1.329 pacientes com SCA de um único centro, realizado entre 2004 e 2006. A função diastólica foi determinada através da PDFVE. A população foi dividida em dois grupos: Grupo A - PDFVE < 26,5 mmHg (n = 449); Grupo B - PDFVE > 26,5 mmHg (n = 226). RESULTADOS: Não houve diferenças significantes entre os grupos em relação aos fatores de risco para doença cardiovascular, histórico médico e terapia médica durante a admissão. Nos pacientes do grupo A, a SCA sem elevação do segmento ST foi mais frequente, bem como angiogramas coronários normais. A mortalidade hospitalar foi similar entre os grupos, mas a sobrevida de um ano foi maior entre os pacientes do grupo A (96,9 vs 91,2 por cento, log rank p = 0,002). Em um modelo multivariado de regressão de Cox, uma PDFVE > 26,5 mmHg (RR 2,45, IC95 por cento 1,05 - 5,74) permaneceu um preditor independente para mortalidade de um ano, quando ajustado para idade, fração de ejeção sistólica do VE, SCA com elevação do segmento ST, pico da troponina, glicemia na admissão hospitalar e diuréticos após 24 horas. Além disso, uma PDFVE > 26,5 mmHg foi um preditor independente de uma futura rehospitalização por IC congestiva (RR 6,65 IC95 por cento 1,74 - 25,5). CONCLUSÃO: Em nossa população selecionada, a PDFVE apresentou uma influência prognóstica significante.

BACKGROUND: Data is lacking in the literature regarding the prognostic impact of left ventricular-end diastolic pressure (LVEDP) across acute coronary syndromes (ACS). OBJECTIVE: To assess LVEDP and its prognostic implications in ACS patients. METHODS: Prospective, longitudinal and continuous study of 1329 ACS patients from a single center between 2004 and 2006. Diastolic function was determined by LVEDP. Population was divided in two groups: A - LVEDP < 26.5 mmHg (n = 449); group B - LVEDP > 26.5 mmHg (n = 226). RESULTS: There were no significant differences between groups with respect to risk factors for cardiovascular disease, medical history and medical therapy during admission. In group A, patients with non-ST elevation ACS were more frequent, as well as normal coronary angiograms. In-hospital mortality was similar between groups, but one-year survival was higher in group A patients (96.9 vs 91.2 percent, log rank p = 0.002). On a multivariate Cox regression model, a LVEDP > 26.5 mmHg (HR 2.45, 95 percentCI 1.05 - 5.74) remained an independent predictor for one-year mortality, when adjusted for age, LV systolic ejection fraction, ST elevation ACS, peak troponin, admission glycemia, and diuretics at 24 hours. Also, a LVEDP > 26.5 mmHg was an independent predictor for a future readmission due to congestive HF (HR 6.65 95 percentCI 1.74 - 25.5). CONCLUSION: In our selected population, LVEDP had a significant prognostic influence.

FUNDAMENTO: Hay falta de datos sobre el impacto pronóstico de la presión diastólica final del ventrículo izquierdo (PDFVI) sobre los síndromes coronarios agudos (SCA). OBJETIVO: Evaluar la PDFVI y sus implicaciones pronósticas en pacientes con SCA. MÉTODOS: Estudio prospectivo, longitudinal y continuo de 1.329 pacientes con SCA de un único centro, realizado entre 2004 y 2006. La función diastólica fue determinada a través de la PDFVI. La población fue dividida en dos grupos: Grupo A - PDFVI < 26,5 mmHg (n = 449); Grupo B - PDFVI > 26,5 mmHg (n = 226). RESULTADOS: No hubo diferencias significativas entre los grupos en relación a los factores de riesgo para enfermedad cardiovascular, historia médica y terapia médica durante la admisión. En los pacientes del grupo A, la SCA sin elevación del segmento ST fue más frecuente, así como angiogramas coronarios normales. La mortalidad hospitalaria fue similar entre los grupos, pero la sobrevida de un año fue mayor entre los pacientes del grupo A (96,9 vs 91,2 por ciento, log rank p = 0,002). En un modelo multivariado de regresión de Cox, una PDFVI > 26,5 mmHg (RR 2,45, IC95 por ciento 1,05 -5,74) permaneció un predictor independiente para mortalidad de un año, cuando fue ajustado para edad, fracción de eyección sistólica del VI, SCA con elevación del segmento ST, pico de la troponina, glicemia en la admisión hospitalaria y diuréticos después de 24 horas. Además de eso, una PDFVI > 26,5 mmHg fue un predictor independiente de una futura rehospitalización por IC congestiva (RR 6,65 IC95 por ciento 1,74 - 25,5). CONCLUSIÓN: En nuestra población seleccionada, la PDFVI presentó una influencia pronóstica significativa.

Carney complex: a case report.

Cardiac myxoma is the most common benign cardiac tumor, and 10% of cases are familial forms. The authors present a review of the literature on the Carney complex, and a case report of a 68-year-old man with a cardiac mass, associated with a significant family history and a diagnosis of coronary embolism.

Dissecçäo aguda da aorta (tipo I de De Bakey), associada a insuficiência aórtica e insuficiência renal aguda: tratamento cirúrgico; relato de caso / Acute dissection of the aorta (type I of De Bakey), associated with aortic insufficiency: surgical treatment, a case report

Um caso de dissecçäo aguda da aorta (tipo I - classificaçäo de De Bakey) associada a insuficiência aórtica apresentou insuficiência renal aguda por provável envolvimento de artéria renal esquerda. O tratamento cirúrgico consistiu na substituiçäo da valva por bioprótese e troca da aorta ascendente por um tubo de "dacron". Houve boa evoluçäo hospitalar e tardia com regressäo total da lesäo renal. Säo comentadas as complicaçöes renais bem como a evoluçäo destes doentes