Frederico Simões do Couto

Acrylic bone cement induces the production of free radicals by cultured human fibroblasts

Arthroplasty with poly(methyl methacrylate) (PMMA) bone cement induces late loosening phenomena that compromise the prosthetic stability. As free radicals are inflammatory mediators and cytotoxic, it seemed useful to investigate whether PMMA induces the liberation of free radicals and/or cytotoxicity. The effect of PMMA interaction on cultured human fibroblasts was accessed by the cell viability test (MTT), and by the measurement of lipoperoxides in the incubation medium. The incubation with the medium exposed to PMMA induced a significant reduction in the viability and a significant increase in lipoperoxide liberation (vs control). These data suggest that PMMA is cytotoxic. This effect seems to be mediated by lipoperoxide and possibly by other free radicals, and may explain the peri-implant loosening phenomena that compromise the prosthetic stability.

Genetic and biochemical markers in patients with Alzheimer's disease support a concerted systemic iron homeostasis dysregulation

Alzheimers disease (AD) is the most common form of dementia in the elderly individuals, resulting from a complex interaction between environmental and genetic factors. Impaired brain iron homeostasis has been recognized as an important mechanism underlying the pathogenesis of this disease. Nevertheless, the knowledge gathered so far at the systemic level is clearly insufficient. Herein, we used an integrative approach to study iron metabolism in the periphery, at both genotypic and phenotypic levels, in a sample of 116 patients with AD and 89 healthy control subjects. To assess the potential impact of iron metabolism on the risk of developing AD, genetic analyses were performed along with the evaluation of the iron status profile in peripheral blood by biochemical and gene expression studies. The results obtained showed a significant decrease of serum iron, ferritin, and transferrin concentrations in patients compared with the control subjects. Also, a significant decrease of ferroportin (SLC40A1) and both transferrin receptors TFRC and TFR2 transcripts was found in peripheral blood mononuclear cells from patients. At the genetic level, significant associations with AD were found for single nucleotide polymorphisms in TF, TFR2, ACO1, and SLC40A1 genes. Apolipoprotein E gene, a well-known risk factor for AD, was also found significantly associated with the disease in this study. Taken together, we hypothesize that the alterations on systemic iron status observed in patients could reflect an iron homeostasis dysregulation, particularly in cellular iron efflux. The intracellular iron accumulation would lead to a rise in oxidative damage, contributing to AD pathophysiology.

TBK1 Mutation Spectrum in an Extended European Patient Cohort with Frontotemporal Dementia and Amyotrophic Lateral Sclerosis

We investigated the mutation spectrum of the TANK‐Binding Kinase 1 (TBK1) gene and its associated phenotypic spectrum by exonic resequencing of TBK1 in a cohort of 2,538 patients with frontotemporal dementia (FTD), amyotrophic lateral sclerosis (ALS), or FTD plus ALS, ascertained within the European Early‐Onset Dementia Consortium. We assessed pathogenicity of predicted protein‐truncating mutations by measuring loss of RNA expression. Functional effect of in‐frame amino acid deletions and missense mutations was further explored in vivo on protein level and in vitro by an NFκB‐induced luciferase reporter assay and measuring phosphorylated TBK1. The protein‐truncating mutations led to the loss of transcript through nonsense‐mediated mRNA decay. For the in‐frame amino acid deletions, we demonstrated loss of TBK1 or phosphorylated TBK1 protein. An important fraction of the missense mutations compromised NFκB activation indicating that at least some functions of TBK1 are lost. Although missense mutations were also present in controls, over three times more mutations affecting TBK1 functioning were found in the mutation fraction observed in patients only, suggesting high‐risk alleles (P = 0.03). Total mutation frequency for confirmed TBK1 LoF mutations in the European cohort was 0.7%, with frequencies in the clinical subgroups of 0.4% in FTD, 1.3% in ALS, and 3.6% in FTD‐ALS.

Escitalopram improves memory deficits induced by maternal separation in the rat

Maternal separation (MS) induces depressive-like behavior and long-term changes in cognition in rats. Escitalopram is an antidepressant drug shown to reverse the depressive-like features caused by this stress model. However, it is not known if it can ameliorate the affected cognition. We now characterized the effect of escitalopram on hippocampal-dependent memory in rats submitted to the MS protocol. Male Wistar rats were assigned either to control (CTR) or maternal separated (MS) group. MS were separated from their dams between 2-14 postnatal days (PND) for 180min daily. Escitalopram was given in food pellets (0.34g/kg/day first 2 weeks and 0.41g/kg/day the subsequent period, average dose 25mg/kg) from PND 43 onwards, during 1 month. Depressive behavior was assessed in the forced swimming test (FST), and memory performance in the Morris water maze (MWM). Escitalopram significantly improved the FSTs latency to despair in the MS group (n=6), but did not change the immobility time. All groups showed a significant learning effect in the MWM over time, but no differences have been found upon treatment (n=6). However, escitalopram treatment significantly increased the time spent on the platform quadrant in the probe trial in the MS group. We report here that chronic treatment with escitalopram is able to improve hippocampal dependent memory in a chronic stress model, while not changing the learning ability. Moreover, this is accompanied by an amelioration of the depressive like behavior. These results support the use of escitalopram to tackle underlying cognitive deficits caused by stress in early-life.

Deep Brain Stimulation for Refractory Cocaine Dependence

Refractory cocaine dependence (RCD) is a severe condition that includes motivational and behavioral disturbances for which there are no specific treatments. A dysfunction of the brainrewarding circuitry (1,2), which includes the nucleus accumbens (Acc), the bed nucleus of the stria terminalis (BNST), the anterior limb of the internal capsule, and the medial forebrain bundle, is thought to underlie RCD. These structures have been implicated in other disorders, such as obsessive-compulsive disorder. For cases of refractory obsessive-compulsive disorder, deep brain stimulation (DBS) emerged as a viable new therapeutic approach (3–11). More recent articles have also shown benefits of DBS for patients with nicotine (12–14), ethanol (15–18), and heroin (19–21) dependence. Although the ideal target is controversial, updated human Acc segmentation based on stereotactic anatomy and magnetic resonance imaging probabilistic tractography (22–25) prompted us to elect its posterior-medial part (Acc shell) plus the neighboring BNST to optimize DBS results. Our main objective was to evaluate the clinical efficacy of DBS in the treatment of RCD. Overall tolerability and safety profiles were also assessed. The present case was subject to a pilot study with a longitudinal double-blind crossover randomized control for 30 months including three phases, as follows:

Cognitive deficits in middle-aged and older adults with bipolar disorder and cognitive complaints: Comparison with mild cognitive impairment

Cognitive impairment has been reported in elderly bipolar disorder (BD) patients, however, few studies have evaluated middle‐aged and older BD patients using standardized cognitive assessments and none (to our knowledge) analysed middle‐aged and older BD patients with recent cognitive complaints. The main objective of this study is to characterize the cognitive deficits of middle‐aged and older patients with BD and compare them with the common age‐related cognitive deficits observed in Mild Cognitive Impairment (MCI).

Age of onset in patients with Alzheimer’s disease with different apoE genotypes

Alzheimer’s disease is the most common form of dementia, affecting about 10% of the elderly population. Four genetic loci have so far been implicated in Alzheimer’s disease, either in rare family pedigrees in which the defective gene (amyloid precursor protein, presenilin-1, presenilin-2) cosegregates with early onset Alzheimer’s disease, or in late onset cases in which polymorphism of the apolipoprotein E (ApoE) gene on the chromosome 19 is identified as an important individual risk trait. Apolipoprotein E is a normal constituent of plasma lipoproteins and has an important role in the maintenance of the integrity of the neuronal membrane and myelin sheath, but is also deposited in senile plaques in Alzheimer’s disease. Three allelic forms of the ApoE gene have been characterised—Apo e2, Apo e3, and Apo e4. In a previous study, we found that the Apo e4 allele constitutes a major risk factor for Alzheimer’s disease in the Portuguese population,1similar to that described for …

Decrease in APP and CP mRNA expression supports impairment of iron export in Alzheimer's disease patients.

Alzheimers disease (AD) is a neurodegenerative disorder of still unknown etiology and the leading cause of dementia worldwide. Besides its main neuropathological hallmarks, a dysfunctional homeostasis of transition metals has been reported to play a pivotal role in the pathogenesis of this disease. Dysregulation of iron (Fe) metabolism in AD has been suggested, particularly at the level of cellular iron efflux. Herein, we intended to further clarify the molecular mechanisms underlying Fe homeostasis in AD. In order to achieve this goal, the expression of specific Fe metabolism-related genes directly involved in Fe regulation and export was assessed in peripheral blood mononuclear cells (PBMCs) from 73AD patients and 74 controls by quantitative PCR. The results obtained showed a significant decrease in the expression of aconitase 1 (ACO1; P=0.007); ceruloplasmin (CP; P<0.001) and amyloid-beta precursor protein (APP; P=0.006) genes in AD patients compared with healthy volunteers. These observations point out to a significant downregulation in the expression of genes associated with ferroportin-mediated cellular Fe export in PBMCs from AD patients, when compared to controls. Taken together, these findings support previous studies suggesting impairment of Fe homeostasis in AD, which may lead to cellular Fe retention and oxidative stress, a typical feature of this disease.

The use of laboratory tests in patients with mild cognitive impairment.

Cognitive decline in elderly people can be caused by a specific and treatable metabolic disorder, and the use of laboratory tests is recommended as part of the diagnostic workup of patients with dementia. Patients with mild cognitive impairment (MCI) are commonly investigated by a similar laboratory diagnostic workup, however it is not known whether this clinical practice is justified. In the present study, we compared the frequencies of laboratory abnormalities, and laboratory abnormalities relevant for cognitive impairment, in consecutive patients with MCI or dementia (all types) observed in a memory clinic setting. As much as 55.1% of patients with MCI and 60.0% of patients with dementia had at least one abnormal laboratory value (a non-significant difference). The most frequent abnormal analysis was the serum cholesterol, that was high in 28.8% of patients with MCI and in 20.4% of patients with dementia. It was possible to detect, both in patients with MCI (1.5% and in patients with dementia (3.5%, a non-significant difference), abnormal metabolic values, indicating poorly controlled diabetes, renal failure, hyponatremia, folate or vitamin B12 deficiency and hyperthyroidism, which correction led to clinical improvement. The majority (62.5% of these alterations were previously unknown. These findings give support to the use of the laboratory diagnostic workup of dementia in patients with mild cognitive impairment.

Depression with melancholic features is associated with higher long-term risk for dementia

BACKGROUND Depression has been reported to increase the risk of subsequently developing dementia, but the nature of this relation remains to be elucidated. Depression can be a prodrome/manifestation of dementia or an early risk factor, and the effect may differ according to depression subtypes. Our aim was to study the association between early-onset depression and different depression subtypes, and the later occurrence of dementia. METHODS We conducted a cohort study including 322 subjects with depression, recruited between 1977 and 1984. A comparison cohort (non-exposed) was recruited retrospectively, to include 322 subjects admitted at the same hospital for routine surgery (appendicectomy or cholecystectomy), at the same period as the depressed cohort. Subjects were contacted again between 2009 and 2014, to assess their dementia status. We computed the risk for dementia in subjects with early onset depression and quantified the association between different depression subtypes (namely melancholic, anxious, and psychotic) and dementia. RESULTS The odds of dementia were increased by 2.90 times (95% C.I. 1.61-5.21; p<0.0001) for the depressed cohort when compared to the surgical cohort. When the analysis was restricted to patients younger than 45 years old at baseline, the odds for dementia in the depressed cohort were also significantly higher when compared to the surgical cohort (8.53; 95% C.I. 2.40-30.16). In the multivariate Cox analysis, subjects having depression with melancholic features had an increased risk for developing dementia compared to those without melancholic features (HR=3.64; 95% C.I. 1.78-11.26; p=0.025). LIMITATIONS About 59% of the participants with depression and 53% of those non-exposed were lost during follow up. The inclusion of biological biomarkers would strengthen the results. The sample included a low number of bipolar patients. CONCLUSIONS These results support depression as an early risk factor for dementia. Depression with melancholic features was found as an important risk factor for dementia, playing a main role in the relation between these disorders.