Cláudia N. Ferreira

Bio: Cláudia N. Ferreira is an academic researcher from Universidade Federal de Minas Gerais. The author has contributed to research in topics: Polycystic ovary & Insulin resistance. The author has an hindex of 13, co-authored 49 publications receiving 537 citations.

Coronary Artery Bypass Surgery Provokes Alzheimer's Disease-Like Changes in the Cerebrospinal Fluid

Abstract: Several biomarkers are used in confirming the diagnosis of cognitive disorders. This study evaluates whether the level of these markers after heart surgery correlates with the development of cognitive dysfunction, which is a frequent complication of cardiac interventions. Concentrations of amyloid-β peptide, tau, and S100β in the cerebro-spinal fluid were assessed, as well as cognitive functions were evaluated before and after coronary artery bypass grafting, utilizing immuno-assays and psychometric tests, respectively. A drastic rise in the level of S100β was observed one week after the surgery, a mark of a severe generalized cerebral injury. The level of amyloid-β peptide significantly decreased, whereas the concentration of tau markedly increased six months postoperatively. Gradual cognitive decline was also present. These findings clearly demonstrate post-surgical cognitive impairment associated with changes in biomarkers similar to that seen in Alzheimer's disease, suggesting a unifying pathognomic factor between the two disorders. A holistic approach to coronary heart disease and Alzheimer's type dementia is proposed.

Thrombin generation assays for global evaluation of the hemostatic system: perspectives and limitations

Abstract: The existing techniques to evaluate hemostasis in clinical laboratories are not sensitive enough to detect hypercoagulable and mild hypocoagulable states. Under different experimental conditions, the thrombin generation test may meet these requirements. This technique evaluates the overall balance between procoagulant and anticoagulant forces and has provided new insights in our understanding of the coagulation cascade, as well as of the diagnosis of hypocoagulability and hypercoagulability conditions. Thrombin generated in the thrombin generation test can be quantified as platelet-rich or platelet-poor plasma using the calibrated automated thrombogram method, which monitors the cleavage of a fluorogenic substrate that is simultaneously compared to the known thrombin activity in a non-clotting plasma sample. The calibrated automated thrombogram method is an open system, in which different antibodies, proteins, enzymes and peptides can be introduced to answer specific questions regarding hemostatic processes. The thrombin generation test has great clinical potential, such as in monitoring patients taking anticoagulants and antiplatelet drugs, screening for genetic or acquired thrombotic disorders, and evaluating bleeding risk control in patients with hemophilia using bypass agents or replacement therapy. Different to conventional coagulation tests, the thrombin generation test can be used for an overall evaluation of hemostasis, the results of which can then be used to evaluate specific characteristics of hemostasis, such as prothrombin time, activated partial thromboplastin time, and levels of fibrinogen and other coagulation factors. The introduction of this method will contribute to a better understanding and evaluation of overall hemostatic processes; however, this method still requires standardization and clinical validation.

Vitamin D receptor polymorphisms and the polycystic ovary syndrome: A systematic review

Abstract: Polycystic ovary syndrome (PCOS) is the most frequent endocrinological disorder that affects women of reproductive age, leading to metabolic alterations, such as hyperandrogenism, obesity, menstrual irregularities, insulin resistance, and polycystic ovaries. The etiology remains unclear, but several genetic and environmental factors have been correlated with manifestations of this syndrome. Vitamin D plays important roles in metabolic pathways affected by PCOS, including calcium homeostasis, the insulin pathway, and sex hormone synthesis. Vitamin D concentration has been related with the severity of this disorder, and vitamin D receptor polymorphisms have been shown in some studies to have an association with some of the patterns presented by PCOS. The objective of this study is to provide an up-to-date review about vitamin D receptor polymorphisms and their association with PCOS.

Polycystic Ovary Syndrome as a systemic disease with multiple molecular pathways: a narrative review.

Abstract: Polycystic Ovary Syndrome (PCOS) is characterized by hyperandrogenism, amenorrhea, and polycystic ovaries. This endocrinopathy is associated with many metabolic disorders such as dyslipidemia and insulin resistance, with increased risk of type 2 diabetes mellitus, metabolic syndrome, and cardiovascular complications. Inflammation is likely to play an important role in the promoting these metabolic imbalances, while prothrombotic and pro-oxidative mechanisms further contribute to the cardiovascular risk of these patients. The etiology of PCOS is still not fully understood, but there is evidence of genetic and environmental components. This review aims to discuss some molecular pathways associated with PCOS that could contribute to the better understanding about this syndrome. Recent evidence suggests that intrauterine exposure of female mice to an excess of anti-Mullerian hormone may induce PCOS features in their post-natal life. High cytokine levels and cytokine gene polymorphisms also appear to be associated with the pathophysiology of PCOS. Furthermore, high levels of microparticles may contribute to the altered hemostasis and enhanced inflammation in PCOS. All these mechanisms may be relevant to clarify some aspects of PCOS pathogenesis and inspire new strategies to prevent the syndrome as well as treat its symptoms and mitigate the risk of long-term complications.

A critical appraisal of amyloid-β-targeting therapies for Alzheimer disease.

Abstract: Brain accumulation of the amyloid-β (Aβ) peptide is believed to be the initial event in the Alzheimer disease (AD) process. Aβ accumulation begins 15–20 years before clinical symptoms occur, mainly owing to defective brain clearance of the peptide. Over the past 20 years, we have seen intensive efforts to decrease the levels of Aβ monomers, oligomers, aggregates and plaques using compounds that decrease production, antagonize aggregation or increase brain clearance of Aβ. Unfortunately, these approaches have failed to show clinical benefit in large clinical trials involving patients with mild to moderate AD. Clinical trials in patients at earlier stages of the disease are ongoing, but the initial results have not been clinically impressive. Efforts are now being directed against Aβ oligomers, the most neurotoxic molecular species, and monoclonal antibodies directed against these oligomers are producing encouraging results. However, Aβ oligomers are in equilibrium with both monomeric and aggregated species; thus, previous drugs that efficiently removed monomeric Aβ or Aβ plaques should have produced clinical benefits. In patients with sporadic AD, Aβ accumulation could be a reactive compensatory response to neuronal damage of unknown cause, and alternative strategies, including interference with modifiable risk factors, might be needed to defeat this devastating disease. Potential disease-modifying therapies for Alzheimer disease have mostly targeted brain accumulation of amyloid-β, but this approach has yet to provide substantial clinical benefits. The authors consider the reasons for this failure and suggest alternative strategies, including modification of risk factors.

Lasting impact of general anaesthesia on the brain: mechanisms and relevance.

Abstract: Some epidemiological studies suggest associations between general anaesthesia and long-term cognitive dysfunction in children and the elderly, although these remain to be proven. Here, Vutskits and Xie review the evidence for general anaesthetic-induced cognitive impairment in young and old rodents and non-human primates, and the potential underlying mechanisms.

Tau phosphorylation and sevoflurane anesthesia: an association to postoperative cognitive impairment.

Abstract: BACKGROUND There is a growing interest in the involvement of anesthetic agents in the etiology of postoperative cognitive dysfunction. Recent animal studies suggest that acute anesthesia induces transient hyperphosphorylation of tau, an effect essentially ascribed to hypothermia. The main aim of the present study was to investigate effects, in normothermic conditions, of acute or repeated exposure to sevoflurane, a halogenated anesthetic agent, on hippocampal tau phosphorylation and spatial memory in adult mice. METHODS 5 to 6-month-old C57Bl6/J mice were submitted to acute (1 h) or repeated (five exposures of 1h every month) anesthesia using 1.5 or 2.5% sevoflurane, in normothermic conditions. In the acute protocol, animals were sacrificed 1 and 24 h after exposure. In the chronic protocol, spatial memory was evaluated using the Morris water maze following the fourth exposure, and tau phosphorylation evaluated 1 month following the last exposure using bi- and mono-dimensional electrophoresis. RESULTS Acute sevoflurane anesthesia in normothermic conditions led to a significant dose-dependent and reversible hippocampal tau phosphorylation, 1 h following the end of exposure (P < 0.001). Conversely, repeated anesthesia led to persistent tau hyperphosphorylation and significant memory impairments, as seen in the retention phase of the Morris water maze in sevoflurane-anesthesized animals. These pathologic features may be related to the activation of both Akt and Erk pathways. CONCLUSIONS The present study demonstrates, in mice, that sevoflurane exposure is associated with increased tau phosphorylation through specific kinases activation and spatial memory deficits. These data support a correlation between exposures to this anesthetic agent and cognitive decline.

Human Alzheimer and Inflammation Biomarkers after Anesthesia and Surgery

Abstract: Background The prevalence of post-operative cognitive disturbance, coupled with growing in vitro, cell and animal evidence suggesting anesthetic effects on neurodegeneration, calls for further study of the interaction between surgical care and Alzheimer neuropathology. Here, we study human cerebral spinal fluid (CSF) biomarkers perioperatively.

Polycystic Ovaries A Common Finding in Normal Women

Abstract: The prevalence of polycystic ovaries (PCO) in normal women of reproductive age was determined by pelvic ultrasound scanning of 257 volunteers who considered themselves to be normal and who had not sought treatment for menstrual disturbances, infertility, or hirsutism. All women had completed a menstrual history questionnaire. 99 women were on oral contraceptives at the time of the study. Of the 158 subjects who were not on oral contraceptives 18% had irregular cycles. 116 (73%) women had normal ovaries and 36 (23%) had PCO. 5 women had multifollicular ovaries and 1 had small, unstimulated ovaries. Only 1 woman with normal ovaries had an irregular menstrual cycle. Of the women with PCO, 76% had irregular cycles, and 6 of the 8 with regular cycles were hirsute. Women with and those without PCO differed in distribution of serum LH concentrations although the median values were similar. 25% of women with PCO had LH concentrations which exceeded the upper limit of the normal range. Thus PCO are common in normal women. Some of these women may have clinical and biochemical markers of PCO, which suggest that PCO in women who consider themselves to be normal is part of the same clinical spectrum as the classic Stein-Leventhal syndrome.