Leptin, Both Bad and Good Actor in Cancer.

Leptin is an important regulator of basal metabolism and food intake, with a pivotal role in obesity. Leptin exerts many different actions on various tissues and systems, including cancer, and is considered as a linkage between metabolism and the immune system. During the last decades, obesity and leptin have been associated with the initiation, proliferation and progression of many types of cancer. Obesity is also linked with complications and mortality, irrespective of the therapy used, affecting clinical outcomes. However, some evidence has suggested its beneficial role, called the "obesity paradox", and the possible antitumoral role of leptin. Recent data regarding the immunotherapy of cancer have revealed that overweight leads to a more effective response and leptin may probably be involved in this beneficial process. Since leptin is a positive modulator of both the innate and the adaptive immune system, it may contribute to the increased immune response stimulated by immunotherapy in cancer patients and may be proposed as a good actor in cancer. Our purpose is to review this dual role of leptin in cancer, as well as trying to clarify the future perspectives of this adipokine, which further highlights its importance as a cornerstone of the immunometabolism in oncology.

Methylation of the central transcriptional regulator KLF4 by PRMT5 is required for DNA end resection and recombination.

Cell fitness and survival upon exposure to DNA damage depends on the repair of DNA lesions. Interestingly, cellular identity does affect and finetunes such response, although the molecular basis of such differences between tissues and cell types is not well understood. Thus, a possibility is that DNA repair itself is controlled by the mechanisms that govern cell identity. Here we show that the KLF4, involved in cellular homeostasis, proliferation, cell reprogramming and cancer development, directly regulates resection and homologous recombination proficiency. Indeed, resection efficiency follows KLF4 protein levels, i.e. decreases upon KLF4 downregulation and increases when is overexpressed. Moreover, KLF4 role in resection requires its methylation by the methyl-transferase PRMT5. Thus, PRMT5 depletion not only mimics KLF4 downregulation, but also showed an epistatic genetic relationship. Our data support a model in which the methylation of KLF4 by PRMT5 is a priming event required to license DNA resection and homologous recombination.

Malignant paraganglioma and somatotropinoma in a patient with germline SDHB mutation-genetic and clinical features.

BACKGROUND: Pituitary adenomas and paragangliomas/pheocromocytomas are rare endocrine tumours, which can be sporadic or familial. During many years their coexistence in the same individual was considered a coincidental finding. However, an association between these two entities was recently demonstrated, with the possible involvement of SDHx genes. CASE REPORT: We describe a 57-year-old female patient, who was under surveillance since 1997 for a malignant paraganglioma with vertebral bone metastasis, and harboured a germline frameshift mutation in exon 6 of SDHB gene [c.587-591DelC]. Seventeen years later, she was diagnosed with acromegaly and underwent transesphenoidal endoscopic resection of a somatotropinoma. Three months after surgery she started treatment with lanreotide for residual disease. Despite initial good response, she developed resistance to first generation of somatostatin analogues and treatment had to be switched to pegvisomant. In the immunohistochemical staining, the pituitary adenoma was positive for SDHA expression, while SDHB showed an heterogeneous staining pattern, with areas markedly positive and others with positive and negative cells. CONCLUSIONS: Our findings provide useful data for understanding the link between paragangliomas/pheocromocytomas and somatotropinomas. While we confirm the well-established link between SDHB mutations and paragangliomas/pheocromocytomas, particularly with malignant paragangliomas, the preservation-at least partially-of SDHB expression in the somatotropinoma tissue does not allow drawing definite conclusions about the involvement of the SDHB mutation in pituitary adenoma.

Faculty and student perception of innovative evaluation strategies in a medical programme basic area / Percepción de docentes y estudiantes sobre estrategias innovadoras de evaluación en el área básica de un programa de medicina

ABSTRACT Objective: To understand the on-line knowledge examination, the Interdisciplinary Evaluation and Feedback Seminar (SERI in Spanish) and the Objective Structured Clinical Examination (OSCE) as innovative evaluation strategies, based on the perceptions of faculty and students of an medical programme basic area. Materials and methods: Qualitative, microethnographic research. Five focus groups and seven in-depth interviews were conducted with faculty members and students who gave their informed consent and their permission for recording. The data were analysed using open axial coding and emerging categories. Triangulation of sources, authors and techniques was used, and a final report was prepared before returning the information. Results: The strategies studied have strengths and weaknesses; on-line examination is well accepted by the students but there is a lack coordination. Greater faculty training in the use of the platform is required, and it is important to establish mechanisms to avoid potential fraud. SERI favours feedback but there is a need to reduce the risk of affecting self-esteem and to find ways to improve knowledge assessment. OSCE comes closer to the correlation between basic training and clinical practice, but organisation and physical space for stations need to be improved. Conclusions: Innovative evaluation strategies must be the focus of constant review in terms of their structure and implementation in order to strengthen comprehensive student training.

RESUMEN Objetivo: comprender las estrategias innovadoras de evaluación: examen de conocimientos en la plataforma virtual, Seminario de Evaluación y Retroalimentación Interdisciplinar (SERI) y Examen de Conocimientos por Objetivos Estructurado (ECOE), desde las percepciones de docentes y estudiantes del área básica de un programa de medicina. Materiales y métodos: investigación cualitativa, microetnográfica. Se realizaron cinco grupos focales y siete entrevistas en profundidad a docentes y estudiantes, con grabación autorizada y consentimiento informado; se analizó la información mediante codificación abierta y axial, y generación de categorías emergentes. Se utilizó triangulación de fuentes, autores y técnicas, se elaboró informe final, previa devolución de información. Resultados: las estrategias investigadas tienen fortalezas y debilidades, el examen en plataforma es bien recibido por estudiantes pero le falta coordinación. Se necesita mayor capacitación de docentes en el uso de la plataforma, y es importante establecer mecanismos para evitar posibles fraudes. El SERI favorece la retroalimentación, pero se requiere que disminuya el riesgo de vulnerar la autoestima y permita una mejor valoración de conocimientos. El ECOE los acerca a la correlación básico-clínica, pero falta organización y espacio para las estaciones. Conclusiones: las estrategias innovadoras de evaluación deben someterse a una constante revisión desde su estructura y ejecución, fortaleciendo así la formación integral de los estudiantes.

Gender and Health in Spanish Nurses / Gênero e Saúde em Enfermeiras Espanholas / Género y Salud en Enfermeras Españolas

Abstract gender exercises a powerful effect on determining health status: it may limit different rates of exposure to certain risks, different patterns in the quest for treatment or differential impacts of the social economic determinants of health. The object of this study has been to discover the relationships between gender and health in a special group of the Spanish population, male/female nurses. Spanish male (n = 98) and female (n = 98) nurses completed measures of gender norms, and health behavior variables. The analysis of correlations between health variables and gender norms indicates that registering a higher score in gender norms correlates with lower scores in physical and mental health and lifestyles. The logistical regression equations (self-perceived health, mental health and the number of illnesses suffered) identify differences between male and female nurses, with the only common variable being the level of perceived stress.

Resumo O gênero exerce um efeito poderoso na determinação do estado de saúde. Ele pode limitar diferentes níveis de exposição a certos riscos, diferentes padrões na busca por tratamento ou diferentes impactos de determinantes socioeconômicos na saúde. Este estudo teve por objetivo descobrir as relações entre gênero e saúde em um grupo especial da população espanhola, enfermeiros e enfermeiras. Enfermeiros (n = 98) e enfermeiras (n = 98) completaram medidas de normas de gênero e comportamentos de saúde. A análise das correlações entre variáveis de saúde e normas de gênero indicaram que um alto escore nas normas de gênero se correlaciona com baixos escores de saúde física/mental e estilos de vida. As equações de regressão logística (saúde auto percebida, saúde mental e número de dolências) identificaram diferenças entre enfermeiros e enfermeiras; estresse percebido foi a única variável em comum.

Resumen el género ejerce un efecto poderoso en la determinación del estado de salud y puede limitar diferentes niveles de exposición a ciertos riesgos, diferentes patrones en la búsqueda por tratamiento o diferentes impactos de determinantes socioeconómicos en la salud. El objetivo de este estudio fue descubrir las relaciones entre género y salud en un grupo especial de la población española, enfermeros y enfermeras. Enfermeros (n = 98) y enfermeras (n = 98) completaron medidas de normas de género y comportamientos de salud. El análisis de las correlaciones entre variables de salud y de género indicaron que un alto escore en las normas de género se correlaciona con bajos escores de salud física/mental y estilos de vida. Las ecuaciones de regresión logística (salud autopercibida, salud mental y número de dolencias) identificaron diferencias entre enfermeros y enfermeras; estrés percibido ha sido la única variable en común.

Chelerythrine promotes Ca2+-dependent calpain activation in neuronal cells in a PKC-independent manner.

BACKGROUND: Chelerythrine is widely used as a broad range protein kinase C (PKC) inhibitor, but there is controversy about its inhibitory effect. Moreover, it has been shown to exert PKC-independent effects on non-neuronal cells. METHODS: In this study we investigated possible off-target effects of chelerythrine on cultured cortical rodent neurons and a neuronal cell line. RESULTS: We found that 10µM chelerythrine, a commonly used concentration in neuronal cultures, reduces PKC and cAMP-dependent protein kinase substrates phosphorylation in mouse cultured cortical neurons, but not in rat primary cortical neurons or in a striatal cell line. Furthermore, we found that incubation with chelerythrine increases pERK1/2 levels in all models studied. Moreover, our results show that chelerythrine promotes calpain activation as assessed by the cleavage of spectrin, striatal-enriched protein tyrosine phosphatase and calcineurin A. Remarkably, chelerythrine induces a concentration-dependent increase in intracellular Ca2+ levels that mediates calpain activation. In addition, we found that chelerythrine induces ERK1/2- and calpain-independent caspase-3 activation that can be prevented by the Ca2+ chelator BAPTA-AM. CONCLUSIONS: This is the first report showing that chelerythrine promotes Ca2+-dependent calpain activation in neuronal cells, which has consequences for the interpretation of studies using this compound. GENERAL SIGNIFICANCE: Chelerythrine is still marketed as a specific PKC inhibitor and extensively used in signal transduction studies. We believe that the described off-target effects should preclude its use as a PKC inhibitor in future works.

Preoperative Beta Cell Function Is Predictive of Diabetes Remission After Bariatric Surgery.

BACKGROUND: Bariatric surgery can improve glucose metabolism in obese patients with diabetes, but the factors that can predict diabetes remission are still under discussion. The present study aims to examine the impact of preoperative beta cell function on diabetes remission following surgery. MATERIALS AND METHODS: We investigated a cohort of 363 obese diabetic patients who underwent bariatric surgery. The impact of several preoperative beta cell function indexes on diabetes remission was explored through bivariate logistic regression models. RESULTS: Postoperative diabetes remission was achieved in 39.9 % of patients. Younger patients (p < 0.001) and those with lower HbA1c (p = 0.001) at the baseline evaluation had higher odds of diabetes remission. Use of oral anti-diabetics and insulin therapy did not reach statistical significance when they were adjusted for age and HbA1c. Among the evaluated indexes of beta cell function, higher values of insulinogenix index, Stumvoll first- and second-phase indexes, fasting C-peptide, C-peptide area under the curve (AUC), C-peptide/glucose AUC, ISR (insulin secretion rate) AUC, and ISR/glucose AUC predicted diabetes remission even after adjustment for age and HbA1c. Among them, C-peptide AUC had the higher discriminative power (AUC 0.76; p < 0.001). CONCLUSIONS: Patients' age and preoperative HbA1c can forecast diabetes remission following surgery. Unlike other studies, our group found that the use of oral anti-diabetics and insulin therapy were not independent predictors of postoperative diabetes status. Preoperative beta cell function, mainly C-peptide AUC, is useful in predicting diabetes remission, and it should be assessed in all obese diabetic patients before bariatric or metabolic surgery.

A genome-wide screening uncovers the role of CCAR2 as an antagonist of DNA end resection.

There are two major and alternative pathways to repair DNA double-strand breaks: non-homologous end-joining and homologous recombination. Here we identify and characterize novel factors involved in choosing between these pathways; in this study we took advantage of the SeeSaw Reporter, in which the repair of double-strand breaks by homology-independent or -dependent mechanisms is distinguished by the accumulation of green or red fluorescence, respectively. Using a genome-wide human esiRNA (endoribonuclease-prepared siRNA) library, we isolate genes that control the recombination/end-joining ratio. Here we report that two distinct sets of genes are involved in the control of the balance between NHEJ and HR: those that are required to facilitate recombination and those that favour NHEJ. This last category includes CCAR2/DBC1, which we show inhibits recombination by limiting the initiation and the extent of DNA end resection, thereby acting as an antagonist of CtIP.

Effect of different bariatric surgery type on the leukocyte formula.

BACKGROUND: Obesity is associated with higher leukocyte counts, whereas weight loss decreases these counts. It is unknown if different bariatric surgery (BS) types have different effects on leukocytes. OBJECTIVES: The aim of the study was to determine predictors of leukocyte and their subset count variation in patients submitted to BS. SETTING: Tertiary care university hospital, Porto, Portugal. METHODS: This was a retrospective analysis of patients submitted to Roux-en-Y gastric bypass (RYGB), laparoscopic adjustable gastric banding (LAGB), or sleeve gastrectomy (SG). Leukocyte and subset counts were compared between baseline and 1-year postsurgery and between BS types. A multivariate linear regression model was built to study determinants of leukocyte and subset variation. RESULTS: We analyzed 764 patients: 238 submitted to LAGB; 452 to RYGB, and 74 to SG. Mean age was 42 years and 86.6% were women. All BS types were associated with a decrease in leukocyte and neutrophil counts but the variation in body mass index and homeostatic model assessment (HOMA-IR) were the only variables independently associated with a decrease 1-year postsurgery. Monocytes increased in patients submitted to LAGB and decreased in those who underwent RYGB and SG. The BS type was independently associated with monocyte variation. Patients who underwent RYGB and SG had a decrease in monocyte counts of 77/µL and 62/µL, respectively, compared with LAGB. CONCLUSION: Weight and insulin resistance are the main predictors of leukocyte and neutrophil variation after BS. The specific type of BS is a determinant of monocyte count variation independent of the amount of weight loss or the degree of insulin resistance improvement.

Graves' disease in a mediastinal mass presenting after total thyroidectomy for nontoxic multinodular goiter: a case report.

BACKGROUND: Thyrotoxicosis after total thyroidectomy is mostly iatrogenic. Rarely, a hyperfunctional thyroid remnant or ectopic tissue may be the cause. There are few cases of Graves' disease arising from thyroid tissue located in the mediastinum and none in which Graves' disease was diagnosed only after surgery. We report the case of a patient with Graves's disease in a mediastinal thyroid mass presenting 7 years after total thyroidectomy for nontoxic goiter. CASE PRESENTATION: A 67-year-old Caucasian woman presented with palpitations, fatigue and weight loss. She had a history of total thyroidectomy for nontoxic multinodular goiter at the age of 60 without any signs of malignancy on microscopic examination. She had been medicated with levothyroxine 100 µg/day since the surgery without follow-up. She was tachycardic, had no cervical mass or eye involvement. Her thyroid-stimulating hormone levels were suppressed (0.000 µU/mL) and her free thyroxine (3.22 ng/dL) and free triiodothyronine (8.46 pg/mL) levels increased. Neither mediastinal enlargement nor trachea deviation was found on chest roentgenogram. Levothyroxine treatment was stopped but our patient showed no improvement on free thyroxine or free triiodothyronine 10 days later. Thyroglobulin was increased to 294 mg/mL. A cervical ultrasound scan revealed no thyroid remnant. Her anti-thyroid-stimulating hormone receptor antibodies were high (19.7 U/L). Corporal scintigraphy demonstrated increased intrathoracic radioiodine uptake. A computed tomography scan confirmed a 60 × 40 mm mediastinal mass. Methimazole 10 mg/day was started. Three months later, her thyroid function was normal and she underwent surgical resection. Microscopic examination showed thyroid tissue with no signs of malignancy. CONCLUSIONS: Although thyrotoxicosis after total thyroidectomy is mostly due to excessive supplementation, true hyperthyroidism may rarely be the cause, which should be kept in mind. The presence of thyroid tissue after total thyroidectomy in our patient may correspond to a remnant or ectopic thyroid tissue that became hyperfunctional in the presence of anti- thyroid-stimulating hormone receptor antibodies.

Down-regulation of BDNF in cell and animal models increases striatal-enriched protein tyrosine phosphatase 61 (STEP61 ) levels.

Brain-derived neurotrophic factor (BDNF) regulates synaptic strengthening and memory consolidation, and altered BDNF expression is implicated in a number of neuropsychiatric and neurodegenerative disorders. BDNF potentiates N-methyl-D-aspartate receptor function through activation of Fyn and ERK1/2. STriatal-Enriched protein tyrosine Phosphatase (STEP) is also implicated in many of the same disorders as BDNF but, in contrast to BDNF, STEP opposes the development of synaptic strengthening. STEP-mediated dephosphorylation of the NMDA receptor subunit GluN2B promotes internalization of GluN2B-containing NMDA receptors, while dephosphorylation of the kinases Fyn, Pyk2, and ERK1/2 leads to their inactivation. Thus, STEP and BDNF have opposing functions. In this study, we demonstrate that manipulation of BDNF expression has a reciprocal effect on STEP61 levels. Reduced BDNF signaling leads to elevation of STEP61 both in BDNF(+/-) mice and after acute BDNF knockdown in cortical cultures. Moreover, a newly identified STEP inhibitor reverses the biochemical and motor abnormalities in BDNF(+/-) mice. In contrast, increased BDNF signaling upon treatment with a tropomyosin receptor kinase B agonist results in degradation of STEP61 and a subsequent increase in the tyrosine phosphorylation of STEP substrates in cultured neurons and in mouse frontal cortex. These findings indicate that BDNF-tropomyosin receptor kinase B signaling leads to degradation of STEP61 , while decreased BDNF expression results in increased STEP61 activity. A better understanding of the opposing interaction between STEP and BDNF in normal cognitive functions and in neuropsychiatric disorders will hopefully lead to better therapeutic strategies. Altered expression of BDNF and STEP61 has been implicated in several neurological disorders. BDNF and STEP61 are known to regulate synaptic strengthening, but in opposite directions. Here, we report that reduced BDNF signaling leads to elevation of STEP61 both in BDNF(+/-) mice and after acute BDNF knockdown in cortical cultures. In contrast, activation of TrkB receptor results in the degradation of STEP61 and reverses hyperlocomotor activity in BDNF(+/-) mice. Moreover, inhibition of STEP61 by TC-2153 is sufficient to enhance the Tyr phosphorylation of STEP substrates and also reverses hyperlocomotion in BDNF(+/-) mice. These findings give us a better understanding of the regulation of STEP61 by BDNF in normal cognitive functions and in neuropsychiatric disorders.

The Effect of Bariatric Surgery Type on Lipid Profile: An Age, Sex, Body Mass Index and Excess Weight Loss Matched Study.

BACKGROUND: Bariatric surgery improves lipid profile. A still unanswered question is whether this improvement is merely weight-dependent or also results from factors inherent to specificities of the bariatric procedure. We aimed to study lipid profile 1 year after bariatric surgery and compare its changes between the different procedures in patients matched for initial weight and weight loss. METHODS: We retrospectively analysed patients submitted to Roux-en-Y gastric bypass (RYGB), adjustable gastric banding (AGB) or sleeve gastrectomy (SG) between 2010 and 2013. Patients were matched for age (±5 years), sex, pre-surgery body mass index (BMI) (±2 Kg/m(2)) and excess weight loss (EWL) (±5%). Baseline and 1-year lipid profile, its variation and percentage of variation was compared between surgeries. RESULTS: We analysed 229 patients: 72 pairs RYGB-AGB, 47 pairs RYGB-SG and 33 pairs AGB-SG. The median age was 41 (35-52) years and 11.8% were male. Pre-operative BMI was 44.0 ± 4.6 and 32.1 ± 4.4 Kg/m(2) at 1 year. EWL at 1 year was 64.2 ± 18.9%. There were no differences in baseline lipid profile between patients submitted to different types of bariatric surgery. At 1 year, high-density lipoprotein cholesterol (HDL) and triglycerides (TG) improved similarly with all surgeries. Total cholesterol (TC) and low-density lipoprotein cholesterol (LDL) at 1 year decreased significantly more in patients submitted to RYGB than in weight-matched patients undergoing AGB or SG. CONCLUSIONS: RYGB is the only bariatric surgery that reduces TC and LDL in age-, sex-, BMI- and EWL-matched patients. All three procedures improved TG and HDL similarly when the confounding effect of weight loss is eliminated.

Permanent neonatal diabetes by a new mutation in KCNJ11: unsuccessful switch to sulfonylurea

Permanent neonatal diabetes (PNDM) can result from activating heterozygous mutations in KCNJ11 gene, encoding the Kir6.2 subunit of the pancreatic ATP-sensitive potassium channels (KATP). Sulfonylureas promote KATP closure and stimulate insulin secretion, being an alternative therapy in PNDM, instead of insulin. Male, 20 years old, diagnosed with diabetes at 3 months of age. The genetic study identified a novel heterozygous mutation in exon 1 of the KCNJ11 gene – KCNJ11:c1001G>7 (p.Gly334Val) – and confirmed the diagnosis of PNDM. Therefore it was attempted to switch from insulin therapy to sulfonylurea. During glibenclamide institution C-peptide levels increased, however the suboptimal glycemic control lead us to restart an intensive insulin scheme. This new variant of KCNJ11 mutation had a phenotypic lack of response to sulfonylurea therapy. Age, prior poor metabolic control and functional change of KATP channel induced by this specific mutation may explain the observed unsuccessful switch to sulfonylurea. Interestingly, C-peptide levels raise during glibenclamide administration support some degree of improvement in insulin secretory capacity induced by the treatment. Understanding the response to sulfonylurea is crucial as successful treatment may be life-changing in these patients.

Hyperactivation of D1 and A2A receptors contributes to cognitive dysfunction in Huntington's disease.

Stimulation of dopamine D1 receptor (D1R) and adenosine A2A receptor (A2AR) increases cAMP-dependent protein kinase (PKA) activity in the brain. In Huntington's disease, by essentially unknown mechanisms, PKA activity is increased in the hippocampus of mouse models and patients and contributes to hippocampal-dependent cognitive impairment in R6 mice. Here, we show for the first time that D1R and A2AR density and functional efficiency are increased in hippocampal nerve terminals from R6/1 mice, which accounts for increased cAMP levels and PKA signaling. In contrast, PKA signaling was not altered in the hippocampus of Hdh(Q7/Q111) mice, a full-length HD model. In line with these findings, chronic (but not acute) combined treatment with D1R plus A2AR antagonists (SCH23390 and SCH58261, respectively) normalizes PKA activity in the hippocampus, facilitates long-term potentiation in behaving R6/1 mice, and ameliorates cognitive dysfunction. By contrast, chronic treatment with either D1R or A2AR antagonist alone does not modify PKA activity or improve cognitive dysfunction in R6/1 mice. Hyperactivation of both D1R and A2AR occurs in HD striatum and chronic treatment with D1R plus A2AR antagonists normalizes striatal PKA activity but it does not affect motor dysfunction in R6/1 mice. In conclusion, we show that parallel alterations in dopaminergic and adenosinergic signaling in the hippocampus contribute to increase PKA activity, which in turn selectively participates in hippocampal-dependent learning and memory deficits in HD. In addition, our results point to the chronic inhibition of both D1R and A2AR as a novel therapeutic strategy to manage early cognitive impairment in this neurodegenerative disease.

BRCA1 accelerates CtIP-mediated DNA-end resection.

DNA-end resection is a highly regulated and critical step in the response and repair of DNA double-strand breaks. In higher eukaryotes, CtIP regulates resection by integrating cellular signals via its posttranslational modifications and protein-protein interactions, including cell-cycle-controlled interaction with BRCA1. The role of BRCA1 in DNA-end resection is not clear. Here, we develop an assay to study DNA resection in higher eukaryotes at high resolution. We demonstrate that the BRCA1-CtIP interaction, albeit not essential for resection, modulates the speed at which this process takes place.

Competing roles of DNA end resection and non-homologous end joining functions in the repair of replication-born double-strand breaks by sister-chromatid recombination.

While regulating the choice between homologous recombination and non-homologous end joining (NHEJ) as mechanisms of double-strand break (DSB) repair is exerted at several steps, the key step is DNA end resection, which in Saccharomyces cerevisiae is controlled by the MRX complex and the Sgs1 DNA helicase or the Sae2 and Exo1 nucleases. To assay the role of DNA resection in sister-chromatid recombination (SCR) as the major repair mechanism of spontaneous DSBs, we used a circular minichromosome system for the repair of replication-born DSBs by SCR in yeast. We provide evidence that MRX, particularly its Mre11 nuclease activity, and Sae2 are required for SCR-mediated repair of DSBs. The phenotype of nuclease-deficient MRX mutants is suppressed by ablation of Yku70 or overexpression of Exo1, suggesting a competition between NHEJ and resection factors for DNA ends arising during replication. In addition, we observe partially redundant roles for Sgs1 and Exo1 in SCR, with a more prominent role for Sgs1. Using human U2OS cells, we also show that the competitive nature of these reactions is likely evolutionarily conserved. These results further our understanding of the role of DNA resection in repair of replication-born DSBs revealing unanticipated differences between these events and repair of enzymatically induced DSBs.

Increased 90-kDa ribosomal S6 kinase (Rsk) activity is protective against mutant huntingtin toxicity.

BACKGROUND: The 90-kDa ribosomal S6 kinase (Rsk) family is involved in cell survival. Rsk activation is regulated by sequential phosphorylations controlled by extracellular signal-regulated kinase (ERK) 1/2 and 3-phosphoinositide-dependent protein kinase 1 (PDK1). Altered ERK1/2 and PDK1 phosphorylation have been described in Huntington's disease (HD), characterized by the expression of mutant huntingtin (mhtt) and striatal degeneration. However, the role of Rsk in this neurodegenerative disease remains unknown. Here, we analyzed the protein levels, activity and role of Rsk in in vivo and in vitro HD models. RESULTS: We observed increased protein levels of Rsk1 and Rsk2 in the striatum of Hdh(Q111/Q111) and R6/1 mice, STHdh(Q111/Q111) cells and striatal cells transfected with full-length mhtt. Analysis of the phosphorylation of Rsk in Hdh mice and STHdh cells showed reduced levels of phospho Ser-380 (dependent on ERK1/2), whereas phosphorylation at Ser-221 (dependent on PDK1) was increased. Moreover, we found that elevated Rsk activity in STHdh(Q111/Q111) cells was mainly due to PDK1 activity, as assessed by transfection with Rsk mutant constructs. The increase of Rsk in STHdh(Q111/Q111) cells occurred in the cytosol and in the nucleus, which results in enhanced phosphorylation of both cytosolic and nuclear Rsk targets. Finally, pharmacological inhibition of Rsk, knock-down and overexpression experiments indicated that Rsk activity exerts a protective effect against mhtt-induced cell death in STHdh(Q7/Q7) cells transfected with mhtt. CONCLUSION: The increase of Rsk levels and activity would act as a compensatory mechanism with capacity to prevent mhtt-mediated cell death. We propose Rsk as a good target for neuroprotective therapies in HD.

Increased PKA signaling disrupts recognition memory and spatial memory: role in Huntington's disease.

Huntington's disease (HD) patients and mouse models show learning and memory impairment even before the onset of motor symptoms. However, the molecular events involved in this cognitive decline are still poorly understood. Here, using three different paradigms, the novel object recognition test, the T-maze spontaneous alternation task and the Morris water maze, we detected severe cognitive deficits in the R6/1 mouse model of HD before the onset of motor symptoms. When we examined the putative molecular pathways involved in these alterations, we observed hippocampal cAMP-dependent protein kinase (PKA) hyper-activation in naïve R6/1 mice compared with wild-type (WT) mice, whereas extracellular signal-regulated kinase 1/2 and calcineurin activities were not modified. Increased PKA activity resulted in hyper-phosphorylation of its substrates N-methyl-D-aspartate receptor subunit 1, Ras-guanine nucleotide releasing factor-1 and striatal-enriched protein tyrosine phosphatase, but not cAMP-responsive element binding protein or the microtubule-associated protein tau. In correlation with the over-activation of the PKA pathway, we found a down-regulation of the protein levels of some phosphodiesterase (PDE) 4 family members. Similar molecular changes were found in the hippocampus of R6/2 mice and HD patients. Furthermore, chronic treatment of WT mice with the PDE4 inhibitor rolipram up-regulated PKA activity, and induced learning and memory deficits similar to those seen in R6 mice, but had no effect on R6/1 mice cognitive impairment. Importantly, hippocampal PKA inhibition by infusion of Rp-cAMPS restored long-term memory in R6/2 mice. Thus, our results suggest that occlusion of PKA-dependent processes is one of the molecular mechanisms underlying cognitive decline in R6 animals.

Diagnóstico ecosonográfico y seguimiento neurológico de porencefalia congénita / Echosonographyc diagnostic and neurological continuation of congenital porencephaly

Se presenta un caso de porencefalia congénita diagnosticado por ultrasonido en la semana 35 del embarazo en una paciente epiléptica. La tomografía axial computarizada confirmó el diagnóstico ecográfico. El examen neurológico neonatal sólo reveló hipotonía de miembros inferiores. Al año de edad la paciente presenta retardo psico-motor, retardo en la adquisición del lenguaje. Electroencefalograma anormal, asimétrico, especifico, sin tendencia paroxística, con tendencia focal. actualmente, 16 meses de edad con hemiplejia izquierda (camina con apoyo)

Ecosonografía, control neurólogico / Ultrasonography, neurological control

Evaluamos y seguimos desde el punto de vista clínico neurológico y ecosonográfico a una muestra de 50 niños con peso inferior a 1.500 gramos al nacer, egresados de la Maternidad "Concepción Palacios". La evaluación clínica neurológica la realizamos siguiendo los patrones del examen neonatal y desarrollo psicomotor de Mme. Saint Anne Dargassies y el estudio ecosonográfico con aparato Dataline General Eletric de tiempo real con transductor lineal de 3,5 Mhz y un Aloka con transductor linieal de 3,5 Mhz. La incidencia de secuelas mayores fue del 12%. Ecosonográficamente tuvimos 30% de HIV y 14% dilataciones ventrículares. En nuestro estudio encontramos al igual que otros autores que a medida que es mayor el grado de severidad de la hemorragia, mayor es la incidencia de secuelas graves. Asimismo obtuvimos que la evolución de los niños con hemorragia sin dilatación no fue muy diferente a los normales ecosonográficamente, así como no la hubo entre los niños con hemorragia ventricular acompañada de dilatación y los que presentaron dilatación sin hemorragia