Differential protein expression in diverse brain areas of Parkinson's and Alzheimer's disease patients

Many hypotheses have been postulated to define the etiology of sporadic Parkinson's and Alzheimer's disorders (PD and AD) but there is no consensus on what causes these devastating age-related diseases. Braak staging of both pathologies helped researchers to better understand the progression and to identify their prodromal and symptomatic phases. Indeed, it is well accepted that Lewy body pathology and neurofibrillary tangles appearance correlates with disease progression and severity of symptoms in PD and AD, respectively. Additionally, several studies in PD and AD models try to disclose which cellular mechanisms are defaulted and trigger the neurodegenerative process that culminates with neuronal death causing PD and AD classical symptomatology. Herein, we determined expression levels of proteins involved in microtubule assembly, autophagic-lysosomal pathway and unfolded protein response in the cortex, hippocampus and SNpc of PD and AD patients, vascular dementia patients and aged-match controls. The differential expression allowed us to determine which pathways are determinant to synaptic dysfunction and to establish a time line for disease progression. Our results allow us to challenge the hypothesis that both PD and AD pathologies are caused by α-synuclein or Aβ pathology propagation throughout the brain in a prion-like manner.

Added sugar and trans fatty acid intake and sedentary behavior were associated with excess total-body and central adiposity in children and adolescents with congenital heart disease

BACKGROUND

Over the past three decades, the prevalence rate of overweight and obesity has increased in survivors with congenital heart disease, and little is known about the body composition and its association with clinical characteristics and lifestyle factors.

OBJECTIVES

To evaluate excess total-body adiposity and central adiposity and, to describe associated factors.

METHODS

Cross-sectional study with children and adolescents who underwent procedure to treat congenital heart disease, from January to July 2017. Sociodemographic and clinical characteristics, and lifestyle factors (dietary intake, physical activity, and sedentary behavior) were assessed. Adiposity was assessed using air-displacement plethysmography and waist circumference. Factors associated with excess total-body adiposity and central adiposity were analyzed using logistic regression models.

RESULTS

Of 232 patients, 22.4% were identified with excess total-body adiposity and 24.6% with central adiposity. Significant factors positively associated with excess total-body adiposity were intake of added sugar and trans fatty acids, adjusted for confounding factors. Similarly, lifestyle factors were positively associated with central adiposity: intake of added sugar and trans fatty acids, sedentary behavior, and family history of obesity.

CONCLUSIONS

Lifestyle factors were associated with excess total-body adiposity and central adiposity. Assessment of body composition and healthy-lifestyle counseling into outpatient care may be the key point to prevent obesity in children and adolescents with congenital heart disease.

Acetylation as a major determinant to microtubule-dependent autophagy: Relevance to Alzheimer's and Parkinson disease pathology

Protein post-translational modifications (PTMs) that potentiate protein aggregation have been implicated in several neurological disorders, including Alzheimer's (AD) and Parkinson's disease (PD). In fact, Tau and alpha-synuclein (ASYN) undergo several PTMs potentiating their aggregation and neurotoxicity. Recent data posits a role for acetylation in Tau and ASYN aggregation. Herein we aimed to clarify the role of Sirtuin-2 (SIRT2) and HDAC6 tubulin deacetylases as well as p300 acetyltransferase in AD and PD neurodegeneration. We used transmitochondrial cybrids that recapitulate pathogenic alterations observed in sporadic PD and AD patient brains and ASYN and Tau cellular models. We confirmed that Tau protein and ASYN are microtubules (MTs)-associated proteins (MAPs). Moreover, our results suggest that α-tubulin acetylation induced by SIRT2 inhibition is functionally associated with the improvement of MT dynamic determined by decreased Tau phosphorylation and by increased Tau/tubulin and ASYN/tubulin binding. Our data provide a strong evidence for a functional role of tubulin and MAPs acetylation on autophagic vesicular traffic and cargo clearance. Additionally, we showed that an accumulation of ASYN oligomers imbalance mitochondrial dynamics, which further compromise autophagy. We also demonstrated that an increase in Tau acetylation is associated with Tau phosphorylation. We found that p300, HDAC6 and SIRT2 influences Tau phosphorylation and autophagic flux in AD. In addition, we demonstrated that p300 and HDAC6 modulate Tau and Tubulin acetylation. Overall, our data disclose the role of Tau and ASYN modifications through acetylation in AD and PD pathology, respectively. Moreover, this study indicates that MTs can be a promising therapeutic target in the field of neurodegenerative disorders in which intracellular transport is altered.

The rescue of microtubule-dependent traffic recovers mitochondrial function in Parkinson's disease

In Parkinson's disease mitochondrial dysfunction can lead to a deficient ATP supply to microtubule protein motors leading to mitochondrial axonal transport disruption. Compromised axonal transport will then lead to a disorganized distribution of mitochondria and other organelles in the cell, as well as, the accumulation of aggregated proteins like alpha-synuclein. Moreover, axonal transport disruption can trigger synaptic accumulation of autophagosomes packed with damaged mitochondria and protein aggregates promoting synaptic failure. We previously observed that neuronal-like cells with an inherent mitochondrial impairment derived from PD patients contain a disorganized microtubule network, as well as, alpha-synuclein oligomer accumulation. In this work we provide new evidence that an agent that promotes microtubule network assembly, NAP (davunetide), improves microtubule-dependent traffic, restores the autophagic flux and potentiates autophagosome-lysosome fusion leading to autophagic vacuole clearance in Parkinson's disease cells. Moreover, NAP is capable of efficiently reducing alpha-synuclein oligomer content and its sequestration by the mitochondria. Most interestingly, NAP decreases mitochondrial ubiquitination levels, as well as, increases mitochondrial membrane potential indicating a rescue in mitochondrial function. Overall, we demonstrate that by improving microtubule-mediated traffic, we can avoid mitochondrial-induced damage and thus recover cell homeostasis. These results prove that NAP may be a promising therapeutic lead candidate for neurodegenerative diseases that involve axonal transport failure and mitochondrial impairment as hallmarks, like Parkinson's disease and related disorders.

Prodromal metabolic phenotype in MCI cybrids: implications for Alzheimer's disease

Mild cognitive impairment (MCI) is considered a nosological entity or a translational state between normal aging and sporadic Alzheimer's disease (AD). From brain tissue to peripheral blood samples, it is evident that the early markers of metabolic dysfunction observed in AD have also been found in MCI subjects. These observations obtained from MCI and AD subjects leave open the possibility that mitochondrial dysfunction-induced oxidative damage happening a priori of symptom onset, may trigger other pathological hallmarks, namely Aβ oligomerization. In this study, we used a citoplasmic hybrid (cybrid) model created by the repopulation of human teratocarcinoma (NT2) cells depleted of endogenous mitochondrial DNA (mtDNA) with platelets from age-matched controls, MCI and AD subjects. We found mitochondrial deficits in MCI and AD cybrids as compared with controls, such as a decrease in cytochrome c oxidase (COX) activity, a decrease in mitochondrial membrane potential and in mitochondrial cytochrome c content. Consequently, we analyzed parameters of oxidative damage and found that AD and MCI cybrids exhibit an increase in lipid peroxides, higher production of superoxide radicals, and higher content in protein carbonyls. Since our data clearly show alterations in mitochondrial-mediated oxidative damage in MCI cybrids we propose that mitochondrial dysfunction is an early event in idiopathic AD. Moreover, we found that mitochondrial Aβ oligomeric content increases in AD, which may exacerbate initial mitochondrial damage. Altogether, our data strongly supports a key role for mitochondria/ mtDNA in aged-driven AD pathology.

Mitochondrial metabolic control of microtubule dynamics impairs the autophagic pathway in Parkinson's disease

BACKGROUND

Parkinson's disease (PD) is a progressive neurodegenerative disorder where the loss of dopaminergic neurons in the substantia nigra and the presence of Lewy bodies in surviving neurons are primary histopathological hallmarks. Recent evidence points to mitochondrial dysfunction as a common upstream event in PD etiopathology.

OBJECTIVE

In this overview, we will discuss some of our findings that provide support for the mitochondrial cascade hypothesis, whereas mitochondrial deficits trigger PD pathology through alterations in microtubule integrity and macroautophagy.

METHODS

Using, as a PD model, cells that have PD patients' mitochondrial DNA, cells without mitochondrial DNA and MPP(+)-treated cells, we showed that mitochondrial metabolism alteration may underlie changes in the microtubular net and in the autophagic-lysosomal pathway.

CONCLUSIONS

Finally, we will endow a potential new therapeutic target for PD pathology.

Mitochondria: the common upstream driver of amyloid-β and tau pathology in Alzheimer's disease

Mitochondrial dysfunction has been widely implicated in the etiology of Alzheimer's disease (AD). Evidence shows a mitochondrial-mediated impairment of autophagy that potentiates amyloid-β (Aβ) deposition. Accordingly, recent data obtained from AD models, in which mitochondrial alterations are a prominent feature, demonstrated abnormalities in microtubule network, involving tubulin and tau post-translational modifications. In this review we will discuss mitochondrial-regulated processes where mitochondrial malfunction is likely to start a sequence of events leading to sirtuin-2 activation, microtubule network breakdown, and impairment of the autophagic pathway. Because sirtuin-2 activity depends on cellular NAD+ availability, mitochondrial regulation of NAD+ levels may contribute to an increase in sirtuin-mediated tubulin deacetylation. A vicious cycle become installed which potentiates tau hyperphosphorylation, together with Aβ overproduction and deposition. Overall, targeting microtubule network constitutes a promising strategy for pharmacological therapy in AD.

Mitochondrial Dysfunction: The Road to Alpha-Synuclein Oligomerization in PD

While the etiology of Parkinson's disease remains largely elusive, there is accumulating evidence suggesting that mitochondrial dysfunction occurs prior to the onset of symptoms in Parkinson's disease. Mitochondria are remarkably primed to play a vital role in neuronal cell survival since they are key regulators of energy metabolism (as ATP producers), of intracellular calcium homeostasis, of NAD(+)/NADH ratio, and of endogenous reactive oxygen species production and programmed cell death. In this paper, we focus on mitochondrial dysfunction-mediated alpha-synuclein aggregation. We highlight some of the findings that provide proof of evidence for a mitochondrial metabolism control in Parkinson's disease, namely, mitochondrial regulation of microtubule-dependent cellular traffic and autophagic lysosomal pathway. The knowledge that microtubule alterations may lead to autophagic deficiency and may compromise the cellular degradation mechanisms that culminate in the progressive accumulation of aberrant protein aggregates shields new insights to the way we address Parkinson's disease. In line with this knowledge, an innovative window for new therapeutic strategies aimed to restore microtubule network may be unlocked.

Mitochondrial control of autophagic lysosomal pathway in Alzheimer's disease

When first described by Alois Alzheimer in 1907, AD was seen as a disorder that causes dementia and characterized by two defining neuropathological lesions, later associated with all forms of AD. While the etiology of AD remains largely unclear, there is accumulating evidence suggesting that mitochondrial dysfunction occurs prior to the onset of symptoms in AD. Mitochondria are exceptionally poised to play a crucial role in neuronal cell survival or death because they are regulators of both energy metabolism and apoptotic pathways. This review is mainly focused in the discussion of evidence suggesting a clear association between mitochondrial dysfunction, autophagy impairment and amyloid-beta accumulation in Alzheimer's disease pathophysiology. The knowledge that autophagic insufficiency may compromise the cellular degradation mechanisms that may culminate in the progressive accumulation of dysfunctional mitochondria, aberrant protein aggregates buildup and lysossomal burden shield new insights to the way we address Alzheimer's disease. In line with this knowledge an innovative window for new therapeutic strategies aimed to activate or ameliorate macroautophagy may be opened.

The key role of mitochondria in Alzheimer's disease

Mitochondria are uniquely poised to play a pivotal role in neuronal cell survival or death because they are regulators of both energy metabolism and apoptotic pathways. This review is mainly focused in the discussion of evidence suggesting a clear association between amyloid-beta toxicity, mitochondrial dysfunction, oxidative stress and neuronal damage/death in Alzheimer's disease pathophysiology. The knowledge that mitochondrial dysfunction has a preponderant role in Alzheimer's disease opened a window for new therapeutic strategies aimed to preserve/ameliorate mitochondrial function. Based on recent developments in mitochondrial research, increased pharmacological and pharmaceutical efforts have lead to the emergence of 'Mitochondrial Medicine' as a whole new field of biomedical research being this topic discussed in the last section of this review.

Neurodegenerative pathways in Parkinson's disease: therapeutic strategies

Parkinson's disease (PD), considered one of the major neurological disorders, is characterized by the loss of dopaminergic neurons in the pars compacta of the substantia nigra and by the presence of intraneuronal cytoplasmic inclusions called Lewy bodies. The causes for degeneration of PD neurons remain unclear, however, recent findings contributed to clarify this issue. This review will discuss the current understanding of the mechanisms underlying Parkinson's disease pathogenesis, focusing on the current and potential therapeutic strategies for human treatment.

Alzheimer's disease-associated neurotoxic mechanisms and neuroprotective strategies

The characteristic hallmarks of Alzheimer's disease (AD), the most common form of dementia in the elderly, include senile plaques, mainly composed of beta-amyloid (Abeta) peptide, neurofibrillary tangles and selective synaptic and neuronal loss in brain regions involved in learning and memory. Genetic studies, together with the demonstration of Abeta neurotoxicity, led to the development of the amyloid cascade hypothesis to explain the AD-associated neurodegenerative process. However, a modified version of this hypothesis has emerged, the Abeta cascade hypothesis, which takes into account the fact that soluble oligomeric forms and protofibrils of Abeta and its intraneuronal accumulation also play a key role in the pathogenesis of the disease. Recent evidence posit that synaptic dysfunction triggered by non fibrillar Abeta species is an early event involved in memory decline in AD. The current understanding of the molecular mechanisms responsible for impaired synaptic function and cognitive deficits is outlined in this review, focusing on oxidative stress and disturbed metal ion homeostasis, Ca(2+) dysregulation, mitochondria and endoplasmic reticulum dysfunction, cholesterol dyshomeostasis and impaired neurotransmission. The activation of apoptotic cell death as a mechanism of neuronal loss in AD, and the prominent role of neuroinflammation in this neurodegenerative disorder, are also reviewed herein. Furthermore, we will focus on the more relevant therapeutical strategies currently used, namely those involving antioxidants, drugs for neurotransmission improvement, hormonal replacement, gamma- and beta- secretase inhibitors, Abeta clearance agents (Abeta immunization, disruption of Abeta fibrils, modulation of the cholesterol-mediated Abeta transport), non-steroidal anti-inflammatory drugs (NSAIDs), microtubules stabilizing drugs and kinase inhibitors.

Organochlorine pesticide residues in European sardine, horse mackerel and Atlantic mackerel from Portugal

This paper reports the results for the surveillance of nine organochlorine pesticides (HCH isomers (alpha, beta, e, gamma), p,p'-DDD, p,p'-DDT, p,p'-DDE, p,p'-DDD, HCB and aldrin) in muscle of three fish species, European pilchard (Sardina pilchardus), Atlantic horse mackerel (Trachurus trachurus) and Atlantic mackerel (Scomber scombrus). Analytical methodology included n-hexane extraction, clean-up with 2% deactivated Florisil, and quantification with gas chromatography-electron capture detection (GC-ECD). The highest mean concentrations were found for p,p'-DDT in sardine and mackerel at levels of 30.1 and 109.9 microg kg(-1), respectively, and for p,p'-DDD in horse mackerel at 51.9 microg kg(-1). Three species had higher levels for S-DDT than S-HCH. The estimated daily intake of organochlorine pesticides in the three species showed that in sardine, the highest EDIs were found for aldrin, at 1.8 ng kg(-1) bw day(-1), which represents 1.8% of the acceptable daily intake (ADI), and for ss-HCH, at 4.0 ng kg(-1) bw day(-1), representing 0.4% of ADI. Lowest values were found for Atlantic mackerel. Statistical analysis to determine the differences in mean concentrations of pesticides between species, and any correlation between groups of residues related with each one of the species, was undertaken.

Protective effect of zinc on amyloid-beta 25-35 and 1-40 mediated toxicity

Amyloid beta-peptide (Abeta) is widely held to be associated with Alzheimer's disease, the insoluble aggregates of the peptide being the major constituents of senile plaques. In this study, we evaluated the effect of Zn(2+) (5, 50 and 200 microM) on Abeta induced toxicity using the human teratocarcinome (NT2) cell line. Our results proved that 50 and 200 microM Zn(2+) protected NT2 cells from Abeta 25-35 toxicity. Zinc was also shown to be effective by preventing the loss of mitochondrial membrane potential (DeltaPsi(m)) induced by Abeta 25-35, not allowing cytochrome c release from mitochondria, and subsequently, caspase 3 activation. However, when the cells were treated with Abeta 1-40, only Zn(2+) 5 microM had a protective effect. We have further observed that 5 microM Zn(2+) prevented Abeta 1-40 aggregation into a beta-sheet structure. Considering the results presented, we argue that Zn(2+) has a concentration-dependent protective effect.

Inhibition of NF-kB renders cells more vulnerable to apoptosis induced by amyloid beta peptides

One of the mechanisms leading to neurodegeneration during Alzheimer's disease (AD) is amyloid beta peptide neurotoxicity. In response to a variety of stress insults, namely oxidative stress, the transcription factor NF-kB can be activated. We have previously shown that amyloid beta peptides 25-35 and 1-40 (A beta 25-35 and A beta 1-40) induces cell death. In response to A beta 25-35 or 1-40 treatment, we observed an increase in superoxide dismutase (SOD) activity in NT2 cells. Amyloid beta peptides also induced an increase in SOD expression levels. This could result from NF-kB activation, as determined by the expression of p65. We observed that the NF-kB inhibitor, PDTC, prevented SOD overexpression after A beta treatment. Previously we have shown that A beta peptides could activate caspases-mediated apoptotic cell death. In this study, we analyzed if NF-kB activation prevented cells from caspases-activation and we also observed that inhibition of NF-kB by PDTC induced an increase in caspase-3 and caspase-6 activation. Taken together, these data suggest that pharmacological induction of NF-kB can be a potential target in Alzheimer's disease treatment.

[An evaluation of the impact of cardiovascular disease prevention in Portugal (1980-1996). A longitudinal Gompertzian analysis of mortality]

The behaviour of cardiovascular diseases has suffered important modifications in recent years. There have been increases in mortality and morbidity in some countries while others have seen stabilization and even reduction. In the countries where we have observed a reduction in cardiovascular mortality, the reasons are multiple: efficacy of prevention measures; improvement of environmental conditions; increase in survival; and competitiveness with other causes of death. In order to ascertain whether a certain tendency is real or fictitious, we need to use techniques that allow the evaluation of the true evolution, to study the effect of environmental factors (not genetic) and the variability of internal resistance (vitality) to disease. Based on the longitudinal Gompertzian analysis of mortality for ischemic heart disease (IHD) and cerebrovascular disease (CVD) between 1980 and 1996, it was possible to observe a reduction in mortality for both causes, which was more obvious in the case of CHD, and that the impact of the improvement in environmental conditions (not genetic) was higher in CVD versus IHD. The prevention of CVD was more efficient in men (42.8% vs 29.7%) than in women, while in IHD the most efficient prevention was 20.6% in women versus 14.9% in men, comparing the data of 1996 and 1980. During this period, the environmental influences (not genetic) were responsible for the reduction in mortality for IHD in 2.7% of men and 4.3% of women, while in CVD we observed a reduction in mortality of 7.5% in men and 4.5% in women.

Mitochondrial function is differentially affected upon oxidative stress

The mechanisms that lead to mitochondrial damage under oxidative stress conditions were examined in synaptosomes treated with ascorbate/iron. A loss of membrane integrity, evaluated by electron microscopy and by LDH leakage, was observed in peroxidized synaptosomes and it was prevented by pre-incubation with vitamin E (150 microM) and idebenone (50 microM). ATP levels decreased, in synaptosomes exposed to ascorbate/iron, as compared to controls. NADH-ubiquinone oxidoreductase (Cx I) and cytochrome c oxidase (Cx IV) activities were unchanged after ascorbate/iron treatment, whereas succinate-ubiquinone oxidoreductase (Cx II), ubiquinol cytochrome c reductase (Cx III) and ATP-synthase (Cx V) activities were reduced by 55%, 40%, and 55%, respectively. The decrease of complex II and ATP-synthase activities was prevented by reduced glutathione (GSH), whereas the other antioxidants tested (vitamin E and idebenone) were ineffective. However, vitamin E, idebenone and GSH prevented the reduction of complex III activity observed in synaptosomes treated with ascorbate/iron. GSH protective effect suggests that the oxidation of protein SH-groups is involved in the inhibition of complexes II, III and V activity, whereas vitamin E and idebenone protection suggests that membrane lipid peroxidation is also involved in the reduction of complex III activity. These results may indicate that the inhibition of the mitochondrial respiratory chain enzymatic complexes, that are differentially affected by oxidative stress, can be recovered by specific antioxidants.

[The spatial grouping of myocardial infarct in Portugal. The application of the methods of Grimson and of Moran]

OBJECTIVES

The objective of this study was to apply techniques of space grouping (clusters) to identify the existence of eventual clusters. The application of these techniques to illnesses, such as cardiovascular ones, may generate work hypotheses, in order to know the dynamics of the risk factors.

MATERIAL AND METHODS

We used two techniques, Grimson's test and the Moran's I for the study of the behaviour of standardised mortality ratio (SMR) for myocardium infarction at a municipal level. The SMR had been calculated by municipalities, for men, women and both in the period of 1985-1989, based on the data of the INE.

RESULTS

We verified that any of the two methods suggests the existence of clusters for the infarct of the myocardium, identifying regions in the country in which SMR are above that expected, implying the presence of "identical denominators" or other common ones.

CONCLUSIONS

The use of these techniques for cardiovascular illnesses could be useful as a scientific form of identifying regions of high and low risk, making it possible for epidemiological studies to be made of the different known and unknown risk factors contributing to the implementation of preventive measures.

The protective effect of vitamin E, idebenone and reduced glutathione on free radical mediated injury in rat brain synaptosomes

In the present study the effect of ascorbate (0.8 mM)/iron (2.5 microM) on lipid and protein oxidation, in Synaptosomes isolated from rat brain cortex, was evaluated. Vitamin E, idebenone and reduced glutathione were used as free radicals scavengers, in order to analyze the mechanism involved in ascorbate/iron-induced oxidative stress. An increased formation of reactive oxygen species (ROS) in the cytosol and in the mitochondria was observed, in ascorbate/iron treated synaptosomes. Idebenone (50 microM) prevented the increased formation of ROS in both synaptosomal compartments, vitamin E (150 microM) protected partially this formation in mitochondria, whereas reduced glutathione (250 microM) (GSH) was ineffective. After ascorbate/iron treatment an increase in lipid peroxidation occurred as compared to control, which was completely inhibited by idebenone. A decrease in protein-SH content was also observed, and it was prevented by Vitamin E, idebenone and GSH. When synaptosomes were treated with ascorbate/iron the levels of GSH decreased, and the levels of oxidized glutathione (GSSG) increased as compared to controls under these conditions. Glutathione peroxidase activity was unchanged, whereas an inhibition of glutathione reductase activity was observed. These data suggest that the increased formation of free radicals in synaptosomes leads to lipid and protein oxidation, the role of the endogenous GSH being essential to protect protein thiol-groups against oxidative damage in order to maintain enzyme activity.

[Measurement discrepancies (analysis of consistency between 2 methods)]

Our purpose was to study the agreement between two methods with clinical impact. Usually, many techniques are not correct for the analysis of concordance. Otherwise, it is normal to confuse association and concordance. We intend to prove that two methods can show a strong association and a weak concordance. Nowadays we must replace "old" methods with new ones, which are more correct and efficient for clinical and research goals.

[The prevalence of cerebrovascular stroke in Coimbra]

The purpose of this study was to assess the prevalence of strokes in a community-based on a sample of the population of the county of Coimbra in 1992 (139,000 inhabitants). The study was made with the collaboration of local general practitioners who randomly selected a sample of 950 individuals over 50 years of age. These individuals were screened for the presence of vascular risk factors and strokes in the past, and submitted to clinical and laboratory examinations. There were 86 persons with strokes (crude prevalence 8%: 10.2% male, 6.6% female) the diagnosis being confirmed by neurological examination or analysis of hospital registers. Hypertension was significantly more frequent in patients with strokes (56.8%). Other risk factors had no significant differences. The magnitude of disability associated with stroke was assessed according to the modified Rankin scale. About fifty percent had no significant disability or a slight disability and 20% were severely disabled.