Potential of marine compounds in the treatment of neurodegenerative diseases: a review

Neurodegenerative diseases (ND) are characterized, especially, by the progressive loss of neurons, resulting in neuropsychomotor dysfunctions. Even with a high prevalence, NDs are treated with drugs that alleviate the symptoms of patients, but which develop adverse events and still do not inhibit the progression of the disease. Thus, within a new pharmacological perspective, this review aimed to verify the therapeutic potential of natural compounds of marine origin against ND. For this, an integrative review was carried out, according to the PRISMA methodology, which included steps such as: search, pre-selection and inclusion of articles. The results described revealed species such as Acaudina malpodioides, Holothuria scabra and Xylaria sp., which presented important evidence in relation to Alzheimer's, reducing the generation of ROS, presenting neuroprotective effects and reducing the concentration of Aβ peptide. Regarding Parkinson's disease (PD), another example of ND, the bioactive compounds from Holothuria scabra and Xylaria sp., showed to be able to reduce the degeneration of dopaminergic neurons, reduce the deposition of alpha synuclein and reduce the formation of Mutant Huntingtin protein (Mhtt). The other marine compounds and bioactive substances are also described in this review. In conclusion, the evaluated studies indicate that compounds of marine origin emerge as a promising source of bioactive compounds, revealing an important therapeutic potential for the treatment of ND.

Mild-to-moderate COVID-19 impact on the cardiorespiratory fitness in young and middle-aged populations

The goal of the present study was to compare pulmonary function test (PFT) and cardiopulmonary exercise test (CPET) performance in COVID-19 survivors with a control group (CG). This was a cross-sectional study. Patients diagnosed with COVID-19, without severe signs and symptoms, were evaluated one month after the infection. Healthy volunteers matched for sex and age constituted the control group. All volunteers underwent the following assessments: i) clinical evaluation, ii) PTF; and iii) CPET on a cycle ergometer. Metabolic variables were measured by the CareFusion Oxycon Mobile device. In addition, heart rate responses, peak systolic and diastolic blood pressure, and perceived exertion were recorded. Twenty-nine patients with COVID-19 and 18 healthy control subjects were evaluated. Surviving patients of COVID-19 had a mean age of 40 years and had higher body mass index and persistent symptoms compared to the CG (P<0.05), but patients with COVID-19 had more comorbidities, number of medications, and greater impairment of lung function (P<0.05). Regarding CPET, patients surviving COVID-19 had reduced peak workload, oxygen uptake (V̇O₂), carbon dioxide output (V̇CO₂), circulatory power (CP), and end-tidal pressure for carbon dioxide (P_ETCO₂) (P<0.05). Additionally, survivors had depressed chronotropic and ventilatory responses, low peak oxygen saturation, and greater muscle fatigue (P<0.05) compared to CG_. Despite not showing signs and symptoms of severe disease during infection, adult survivors had losses of lung function and cardiorespiratory capacity one month after recovery from COVID-19. In addition, cardiovascular, ventilatory, and lower limb fatigue responses were the main exercise limitations.

Assessing sociodemographic differences in human papillomavirus vaccine impact studies in the United States: a systematic review using narrative synthesis

OBJECTIVES

Sociodemographic disparities in the incidence and mortality of human papillomavirus (HPV)-associated conditions have been well documented in the pre-HPV vaccine era. It is still unknown if the introduction of routine vaccination has been effective in reducing these prevaccine era inequalities. The purpose of this review was to determine the utilization of sociodemographic variables to assess for disparities in population-level HPV vaccine impact research and to evaluate the current evidence for disparities in the reduction of HPV-associated conditions after vaccine introduction in the United States (US).

STUDY DESIGN

A systematic review of the literature from January 2007 through March 2018 was carried out to identify studies evaluating the impact HPV vaccines have had on the rates of HPV infection, genital warts, and cervical dysplasia (cervical intraepithelial neoplasia grades 1+) in the US. An in-depth review was then performed to synthesize these data and to assess the way prior studies have reported and evaluated for potential disparities in the vaccine's impact within various racial, ethnic, and/or socio-economic subgroups of the population.

METHODS

Vaccine impact studies measure the change in the population-level burden of disease prelicensure versus postlicensure of the vaccine. We systematically searched PubMed/Medline and Embase, combining search terms related to the HPV vaccine, sentinel surveillance, and HPV-associated conditions. Eligible studies were those with population-level, postvaccine introduction data that were conducted in the US. Finally, a cited reference search was conducted for all included articles using the Web of Science platform that accesses three major citation indexes: Science Citation Index, Social Sciences Citation Index, and Arts and Humanities Citation Index. This allowed us to screen not only the articles that were cited by our final collection of studies but also the articles that used our selected studies as one of their references. The study protocol is registered in PROSPERO (#CRD42018107579).

RESULTS

Overall, 23 of the 4139 references retrieved assessed the population-level impact of HPV vaccines between January 1, 2007, and March 29, 2018. Among these, 13 (57%) reported sociodemographic data. Only two articles reported stratified results by sociodemographic factors, thereby allowing assessment for potential disparate impact. One of these studies described differences in the impact of the vaccine by race, ethnicity, and income.

CONCLUSION

Although approximately half of the studies that assessed the impact of the HPV vaccine measured sociodemographic characteristics, few presented results in a way that allowed for the identification of potential differences in impact between the relevant subgroups of the population. Determining to what extent, if any, vaccines are reducing known sociodemographic disparities is an important public health priority and an essential step in developing immunization strategies that are beneficial for all.

Pyrethrum extract encapsulated in nanoparticles: Toxicity studies based on genotoxic and hematological effects in bullfrog tadpoles

The environment receives about 2.7 kg.ha^-1 annually of pesticides, used in crop production. Pesticides may have a negative impact on environmental biodiversity and potentially induce physiological effects on non-target species. Advances in technology and nanocarrier systems for agrochemicals led to new alternatives to minimize these impacts, such as nanopesticides, considered more efficient, safe and sustainable. However, it is important to evaluate the risk potential, action and toxicity of nanopesticides in aquatic and terrestrial organisms. This study aims to evaluate genotoxic and hematological biomarkers in bullfrog tadpoles (Lithobates catesbeianus) submitted to acute exposure (48 h) to pyrethrum extract (PYR) and solid lipid nanoparticles loaded with PYR. Results showed increased number of leukocytes during acute exposure, specifically eosinophils in nanoparticle-exposed groups, and basophil in PYR-exposed group. Hematological analysis showed that PYR encapsulated in nanoparticles significantly increased the erythrocyte number compared to the other exposed groups. Data from the comet assay indicated an increase in frequency of the classes that correspond to more severe DNA damages in exposed groups, being that the PYR-exposed group showed a high frequency of class-4 DNA damage. Moreover, erythrocyte nuclear abnormalities were triggered by short-time exposure in all treatments, which showed effects significantly higher than the control group. These results showed genotoxic responses in tadpoles, which could trigger cell death pathways. Concluding, these analyses are important for applications in assessment of contaminated aquatic environments and their biomonitoring, which will evaluate the potential toxicity of xenobiotics, for example, the nanoparticles and pyrethrum extract in frog species. However, further studies are needed to better understand the effects of nanopesticides and botanical insecticides on non-target organisms, in order to contribute to regulatory aspects of future uses for these systems.

Validation of the two-minute step test in obese with comorbibities and morbidly obese patients

Cardiopulmonary fitness assessment is a valuable resource to obtain quantitative indicators of an individual's physical performance. The cardiopulmonary exercise test (CPX), considered the gold standard test for this evaluation, is costly and difficult to be accessed by the general population. In order to make this evaluation more accessible, and to better reflect the performance of daily life activities, alternative tests were proposed. Morbidly obese patients present limitations that impair physical performance assessment and could benefit from a test of shorter duration, provided it is validated. This observational study aimed to validate the two-minute step test (2MST) as a tool to evaluate functional capacity (FC) in obese with comorbidities and morbidly obese patients, compared the 2MST with CPX as a measure of physical performance, and developed a predictive equation to estimate peak oxygen uptake (VO₂) in the 2MST. The CPX and the 2MST were performed and metabolic and ventilatory parameters were recorded in 31 obese individuals (BMI>35 kg/m²). Pearson correlation and multiple linear regression analyses were performed to evaluate the peak VO₂ best predictors. Bland-Altman analysis was performed to assess the agreement between the two methods. Peak VO₂ measured by CPX and 2MST showed a strong correlation (r=0.70, P<0.001) and there was a moderate correlation between peak VO₂ of the 2MST and the number of up-and-down step cycles (UDS) (r=0.55; P=0.01). The reference equation obtained was: VO₂ (mL·kg^-1·min^-1) = 13.341 + 0.138 × total UDS – (0.183 × BMI), with an estimated standard error of 1.3 mL·kg^-1·min^-1. The 2MST is a viable, practical, and easily accessible test for FC. UDS and BMI can predict peak VO₂ satisfactorily.

Osteonecrosis of the femoral head in people living with HIV: anatomopathological description and p24 antigen test

Objective

To examine the presence of HIV in bone tissue of people living with HIV (PLWHIV) with osteonecrosis of femoral head and describe clinical and anatomopathological findings.

Design

This is a case series which included 44 PLWHIV with osteonecrosis of femoral head who underwent total hip arthroplasty.

Methods

Clinical data were obtained through analysis of the patients’ medical records. Bone tissue obtained during total hip arthroplasty was retrieved and sent for conventional and immunohistochemical analysis. Monoclonal antibodies were used to mark the p24 (HIV), CD31 (vascular endothelial cells), CD68 (macrophages), and D₂40 (cells of the lymphatic endothelium) antigens.

Results

Dyslipidemia was found in 48% of the patients and lipodystrophy in 31%. Histological analysis showed similar characteristics for the entire sample. Degeneration of joint cartilage was visualized with the presence of fissures and fibrillations, as well as subchondral sclerosis and necrosis of the subchondral cancellous bone tissue. Lymphoplasmocytic inflammatory reaction was observed, with the presence of macrophages containing a foamy, vacuolated cytoplasm, as well as the presence of ceroid pigment and occasional granulation tissue. The reaction with the monoclonal anti-p24 antibody was negative in the samples from all 44 PLWHIV undergoing hip arthroplasty. Reactions with the anti-CD31 and anti-D₂40 antibodies were negative. Staining with CD68 antibody confirmed that the cells visualized with foamy, vacuolated cytoplasm were macrophages.

Conclusion

p24 HIV antigen was not detected in the bone tissue of PLWHIV and osteonecrosis. The most frequent anatomopathological findings were extensive necrosis of bone tissue, large vacuoles filled with fat cells, inflammatory lymphoplasmocytic reaction with macrophages containing vacuolated cytoplasm, and the presence of ceroid pigment.

Does the incremental shuttle walk test require maximal effort in young obese women?

Obesity is a chronic disease with a multifaceted treatment approach that includes nutritional counseling, structured exercise training, and increased daily physical activity. Increased body mass elicits higher cardiovascular, ventilatory and metabolic demands to varying degrees during exercise. With functional capacity assessment, this variability can be evaluated so individualized guidance for exercise training and daily physical activity can be provided. The aim of the present study was to compare cardiovascular, ventilatory and metabolic responses obtained during a symptom-limited cardiopulmonary exercise test (CPX) on a treadmill to responses obtained by the incremental shuttle walk test (ISWT) in obese women and to propose a peak oxygen consumption (VO2) prediction equation through variables obtained during the ISWT. Forty obese women (BMI ≥30 kg/m2) performed one treadmill CPX and two ISWTs. Heart rate (HR), arterial blood pressure (ABP) and perceived exertion by the Borg scale were measured at rest, during each stage of the exercise protocol, and throughout the recovery period. The predicted maximal heart rate (HRmax) was calculated (210 - age in years) (16) and compared to the HR response during the CPX. Peak VO2 obtained during CPX correlated significantly (P<0.05) with ISWT peak VO2 (r=0.79) as well as ISWT distance (r=0.65). The predictive model for CPX peak VO2, using age and ISWT distance explained 67% of the variability. The current study indicates the ISWT may be used to predict aerobic capacity in obese women when CPX is not a viable option.

Middle-Aged Diabetic Females and Males Present Distinct Susceptibility to Alzheimer Disease-like Pathology

Type 2 diabetes (T2D) is a highly concerning public health problem of the twenty-first century. Currently, it is estimated that T2D affects 422 million people worldwide with a rapidly increasing prevalence. During the past two decades, T2D has been widely shown to have a major impact in the brain. This, together with the cognitive decline and increased risk for dementia upon T2D, may arise from the complex interaction between normal brain aging and central insulin signaling dysfunction. Among the several features shared between T2D and some neurodegenerative disorders (e.g., Alzheimer disease (AD)), the impairment of insulin signaling may be a key link. However, these may also involve changes in sex hormones' function and metabolism, ultimately contributing to the different susceptibilities between females and males to some pathologies. For example, female sex has been pointed as a risk factor for AD, particularly after menopause. However, less is known on the underlying molecular mechanisms or even if these changes start during middle-age (perimenopause). From the above, we hypothesized that sex differentially affects hormone-mediated intracellular signaling pathways in T2D brain, ultimately modulating the risk for neurodegenerative conditions. We aimed to evaluate sex-associated alterations in estrogen/insulin-like growth factor-1 (IGF-1)/insulin-related signaling, oxidative stress markers, and AD-like hallmarks in middle-aged control and T2D rat brain cortices. We used brain cortices homogenates obtained from middle-aged (8-month-old) control Wistar and non-obese, spontaneously T2D Goto-Kakizaki (GK) male and female rats. Peripheral characterization of the animal models was done by standard biochemical analyses of blood, plasma, or serum. Steroid sex hormones, oxidative stress markers, and AD-like hallmarks were given by specific ELISA kits and colorimetric techniques, whereas the levels of intracellular signaling proteins were determined by Western blotting. Albeit the high levels of plasma estradiol and progesterone observed in middle-aged control females suggested that they were still under their reproductive phase, some gonadal dysfunction might be already occurring in T2D ones, hence, anticipating their menopause. Moreover, the higher blood and lower brain cholesterol levels in female rats suggested that its dysfunctional uptake into the brain cortex may also hamper peripheral estrogen uptake and/or its local brain steroidogenic metabolism. Despite the massive drop in IGF-1 levels in females' brains, particularly upon T2D, they might have developed some compensatory mechanisms towards the maintenance of estrogen, IGF-1, and insulin receptors function and of the subsequent Akt- and ERK1/2-mediated signaling. These may ultimately delay the deleterious AD-like brain changes (including oxidative damage to lipids and DNA, amyloidogenic processing of amyloid precursor protein and increased tau protein phosphorylation) associated with T2D and/or age (reproductive senescence) in female rats. By demonstrating that differential sex steroid hormone profiles/action may play a pivotal role in brain over T2D progression, the present study reinforces the need to establish sex-specific preventive and/or therapeutic approaches and an appropriate time window for the efficient treatment against T2D and AD.

Sporadic Creutzfeldt-Jakob disease diagnostic accuracy is improved by a new CSF ELISA 14-3-3γ assay

Protein 14-3-3 is a reliable marker of rapid neuronal damage, specifically increased in cerebrospinal fluid (CSF) of sporadic Creutzfeldt-Jakob disease (sCJD) patients. Its detection is usually performed by Western Blot (WB), prone to methodological issues. Our aim was to evaluate the diagnostic performance of a recently developed quantitative enzyme-linked immunosorbent (ELISA) assay for 14-3-3γ, in comparison with WB and other neurodegeneration markers. CSF samples from 145 patients with suspicion of prion disease, later classified as definite sCJD (n=72) or Non-prion diseases (Non-CJD; n=73) comprised our population. 14-3-3 protein was determined by WB and ELISA. Total Tau (t-Tau) and phosphorylated Tau (p-Tau) were also evaluated. Apolipoprotein E gene (ApoE) and prionic protein gene (PRNP) genotyping was assessed. ELISA 14-3-3γ levels were significantly increased in sCJD compared to Non-CJD patients (p<0.001), showing very good accuracy (AUC=0.982; sensitivity=97%; specificity=94%), and matching WB results in 81% of all cases. It strongly correlated with t-Tau and p-Tau (p<0.0001), showing slightly higher specificity (14-3-3 WB - 63%; Tau - 90%; p-Tau/t-Tau ratio - 88%). From WB inconclusive results (n=44), ELISA 14-3-3γ correctly classified 41 patients. Additionally, logistic regression analysis selected ELISA 14-3-3γ as the best single predictive marker for sCJD (overall accuracy=93%). ApoE and PRNP genotypes did not influence ELISA 14-3-3γ levels. Despite specificity for 14-3-3γ isoform, ELISA results not only match WB evaluation but also help discrimination of inconclusive results. Our results therefore reinforce this assay as a single screening test, allowing higher sample throughput and unequivocal results.

Potential effect of 6 versus 12-weeks of physical training on cardiac autonomic function and exercise capacity in chronic obstructive pulmonary disease

BACKGROUND

Exercise is an important part of chronic obstructive pulmonary disease (COPD) treatment. However, it is not know about the minimum effective time of physical training that could beneficially modify the cardiac autonomic modulation (CAM) and exercise capacity in these patients.

AIM

To contrast the potential effects of a physical training program (PTP), for 6 versus 12 weeks, on CAM by linear and nonlinear heart rate variability (HRV) indices and exercise capacity in COPD patients.

DESIGN

Prospective randomized controlled trial.

SETTING

Outpatient pulmonary rehabilitation.

POPULATION

Twenty moderate-to-severe COPD patients were randomly assigned to either a training group (N.=10) or a control group (N.=10).

METHODS

HRV at rest and during submaximal test was determined by linear (rMSSD and SDNN) and non-linear indices (SD1, SD2 and sample entropy [SE]). In addition, key responses were obtained during cardiopulmonary exercise testing (CPET), the walking distance (WD) during the six minute walking test and submaximal constant speed testing (CST). PTP consisted of 30 minutes of aerobic exercise training on a treadmill, 3 times per week at 70% of CPET peak speed rate. Patients were evaluated on baseline, 6 and 12 weeks.

RESULTS

Significant improvements in HRV indices, WD, as well as, other physiological responses were observed after 6 weeks of the PTP and maintained until 12 weeks (P<0.05). However, after 12 weeks, the SD1 index demonstrated an additional improvement compared with 6 weeks (P<0.05). Peak oxygen uptake and dioxide carbon production improved only after 12 weeks (P<0.05). Interestingly, the 6th week-baseline delta (6th week-baseline) of WD, SDNN and SE were significantly higher than 12th week-6th week delta (P<0.05).

CONCLUSION

These results indicate that beneficial changes on cardiac autonomic modulation in conjunction with improvement in submaximal functional capacity occur in the first 6 weeks of PTP in moderate to severe COPD.

CLINICAL REHABILITATION IMPACT

Short-term rehabilitation (6 weeks) is an effective sufficient time to beneficially modify important outcomes as cardiac modulation and exercise capacity in COPD patients.

BRI2 ectodomain affects Aβ42 fibrillation and tau truncation in human neuroblastoma cells

Alzheimer's disease (AD) is pathologically characterized by the presence of misfolded proteins such as amyloid beta (Aβ) in senile plaques, and hyperphosphorylated tau and truncated tau in neurofibrillary tangles (NFT). The BRI2 protein inhibits Aβ aggregation via its BRICHOS domain and regulates critical proteins involved in initiating the amyloid cascade, which has been hypothesized to be central in AD pathogenesis. We recently detected the deposition of BRI2 ectodomain associated with Aβ plaques and concomitant changes in its processing enzymes in early stages of AD. Here, we aimed to investigate the effects of recombinant BRI2 ectodomain (rBRI276-266) on Aβ aggregation and on important molecular pathways involved in early stages of AD, including the unfolded protein response (UPR), phosphorylation and truncation of tau, as well as apoptosis. We found that rBRI276-266 delays Aβ fibril formation, although less efficiently than the BRI2 BRICHOS domain (BRI2 residues 113-231). In human neuroblastoma SH-SY5Y cells, rBRI276-266 slightly decreased cell viability and increased up to two-fold the Bax/Bcl-2 ratio and the subsequent activity of caspases 3 and 9, indicating activation of apoptosis. rBRI276-266 upregulated the chaperone BiP but did not modify the mRNA expression of other UPR markers (CHOP and Xbp-1). Strikingly, rBRI276-266 induced the activation of GSK3β but not the phosphorylation of tau. However, exposure to rBRI276-266 significantly induced the truncation of tau, indicating that BRI2 ectodomain can contribute to NFT formation. Since BRI2 can also regulate the metabolism of Aβ, the current data suggests that BRI2 ectodomain is a potential nexus between Aβ, tau pathology and neurodegeneration.

Protective effect of leptin and ghrelin against toxicity induced by amyloid-β oligomers in a hypothalamic cell line

In addition to cognitive decline, Alzheimer's disease (AD) patients also exhibit an unexplained weight loss that correlates with disease progression. In young and middle-aged AD patients, large amounts of amyloid-β (Aβ) deposits were observed in the hypothalamus, a brain region involved in the control of feeding and body weight through the action of peripheral metabolic peptides, which have recently been shown to have neuroprotective effects. Moreover, levels of peripheral metabolic peptides, such as leptin and ghrelin, are changed in AD patients. The present study aimed to investigate the role of Aβ peptide in the survival of hypothalamic cells and to explore the receptor-mediated protective effect of leptin and ghrelin against Aβ-induced toxicity in these cells. Using the mHypoE-N42 cell line, we demonstrated for the first time that oligomeric Aβ is toxic to hypothalamic cells, leading to cell death. It was also demonstrated that leptin and ghrelin protect these cells against AβO-induced cell death through the activation of the leptin and ghrelin receptors, respectively. Furthermore, ghrelin and leptin prevented superoxide production, calcium rise and mitochondrial dysfunction triggered by AβO. Taken together, these results suggest that peripheral metabolic peptides, in particular leptin and ghrelin, might be considered as preventive strategies for ameliorating hypothalamic alterations in AD.

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.

Crosstalk between diabetes and brain: glucagon-like peptide-1 mimetics as a promising therapy against neurodegeneration

According to World Health Organization estimates, type 2 diabetes (T2D) is an epidemic (particularly in under development countries) and a socio-economic challenge. This is even more relevant since increasing evidence points T2D as a risk factor for Alzheimer's disease (AD), supporting the hypothesis that AD is a "type 3 diabetes" or "brain insulin resistant state". Despite the limited knowledge on the molecular mechanisms and the etiological complexity of both pathologies, evidence suggests that neurodegeneration/death underlying cognitive dysfunction (and ultimately dementia) upon long-term T2D may arise from a complex interplay between T2D and brain aging. Additionally, decreased brain insulin levels/signaling and glucose metabolism in both pathologies further suggests that an effective treatment strategy for one disorder may be also beneficial in the other. In this regard, one such promising strategy is a novel successful anti-T2D class of drugs, the glucagon-like peptide-1 (GLP-1) mimetics (e.g. exendin-4 or liraglutide), whose potential neuroprotective effects have been increasingly shown in the last years. In fact, several studies showed that, besides improving peripheral (and probably brain) insulin signaling, GLP-1 analogs minimize cell loss and possibly rescue cognitive decline in models of AD, Parkinson's (PD) or Huntington's disease. Interestingly, exendin-4 is undergoing clinical trials to test its potential as an anti-PD therapy. Herewith, we aim to integrate the available data on the metabolic and neuroprotective effects of GLP-1 mimetics in the central nervous system (CNS) with the complex crosstalk between T2D-AD, as well as their potential therapeutic value against T2D-associated cognitive dysfunction.

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.

MMP(-2) expression in skeletal muscle after strength training

The aim of this study was to assess the effects of resistance training on ladders (RTL) on MMP(-2) expression and blood lactate concentration [La-]. 30 male (3 months of age), albino rats were divided into 3 groups: sedentary control (SC, n=10), low resistance exercise training (Low-IntRT, n=10) and high-intensive exercise training (High-IntRT, n=10). Animals of High-IntRT were submitted to a progressively increasing overload in relation to body weight until exhaustion, while the Low-IntRT group performed the same exercise regimen with no external load. The program had a frequency of 3 times per week over 8 weeks. MMP(-2) expression of tibialis anterior muscle and [La-] were measured. While there was a significant increase of MMP(-2) (pro-form) in both groups, only High-IntRT significantly increased MMP(-2) in active-form (p<0.05). Both trained groups exhibited an increase in [La-] when compared to controls, however, the increase in [La-] was significantly higher in the High-IntRT compared to Low-IntRT (p<0.05). Strong correlation was found between MMP(-2) (active form) and [La-] in High-IntRT (r=0.91). RTL in using low and high-intensity exercise can serve as a model to demonstrate different responses of MMP(-2) expression in an animal model. It appears active form expression of MMP(-2) is modulated by exercise intensity.

IGF-1 protects against diabetic features in an in vivo model of Huntington's disease

Huntington's disease (HD) is the most prevalent polyglutamine expansion disorder. HD is caused by an expansion of CAG triplet in the huntingtin (HTT) gene, associated with striatal and cortical neuronal loss. Central and peripheral metabolic abnormalities and altered insulin-like growth factor-1 (IGF-1) levels have been described in HD. Thus, we hypothesized that restoration of IGF-1-mediated signaling pathways could rescue R6/2 mice from metabolic stress and behavioral changes induced by polyglutamine expansion. We analyzed the in vivo effect of continuous peripheral IGF-1 administration on diabetic parameters, body weight and motor behavior in the hemizygous R6/2 mouse model of HD. We used 9 week-old and age-matched wild-type mice, subjected to continuously infused recombinant IGF-I or vehicle, for 14 days. IGF-1 treatment prevented the age-related decrease in body weight in R6/2 mice. Although blood glucose levels were higher in R6/2 mice, they did not reach a diabetic state. Even though, IGF-1 ameliorated poor glycemic control in HD mice. This seemed to be associated with a decrease in blood insulin levels in R6/2 mice, which was increased following IGF-1 infusion. Similarly, blood IGF-1 levels decreased during aging in both wild-type and R6/2 mice, being significantly improved upon its continuous infusion. Although no significant differences were found in motor function in R6/2-treated mice, IGF-1 treatment highly improved paw clasping scores. In summary, these results suggest that IGF-1 has a protective role against HD-associated impaired glucose tolerance, by enhancing blood insulin levels.

Cell cycle re-entry in Alzheimer's disease: a major neuropathological characteristic?

Alzheimer's disease (AD) is an irreversible, progressive brain disease that slowly destroys memory and thinking skills. With over 26 million patients in 2006, AD is the most prevalent neurodegenerative disease worldwide. Different hypotheses have been suggested to explain the pathogenesis of AD, like those involving inflammation, mitochondrial dysfunction or oxidative stress. Many of these studies have addressed amyloid plaque formation, tau hyperphosphorylation and apoptotic neuronal loss, the three main histopathological hallmarks of this disease. Increasing evidences, however, suggest another feature that can also be considered a neuropathological marker for AD: ectopic cell cycle re-entry. Cell cycle events have been frequently registered in the brains of AD patients. Although the exact starting point of cell cycle re-entry remains unclear, a number of subsequent cascades, which include events such as kinase upregulation, DNA replication and cytoskeletal alterations, have already been described. There are also increasing reports suggesting that cell cycle reactivation in mature neurons occurs as part of the apoptotic process. Upon a brief overview of the different theories and models addressing cell cycle reactivation in AD, we will describe possible mechanisms that trigger cell cycle re-entry, with special attention to links between this feature and the main neuropathological markers of AD. Finally, we will also analyze possible similarities between cell cycle dysregulation in AD and in other pathologies, such as Prion-Related Encephalopathies.

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.

Bcl-2 expression and apoptosis induction in human HL60 leukaemic cells treated with a novel organotellurium(IV) compound RT-04

Organotellurium(IV) compounds have been reported to have multiple biological activities including cysteine protease-inhibitory activity, mainly cathepsin B. As cathepsin B is a highly predictive indicator for prognosis and diagnosis of cancer, a possible antitumor potential for these new compounds is expected. In this work, it was investigated the effectiveness of organotellurium(IV) RT-04 to produce lethal effects in the human promyelocytic leukaemia cell line HL60. Using the MTT tetrazolium reduction test, and trypan blue exclusion assay, the IC50 for the compound after 24 h incubation was 6.8 and 0.35 microM, respectively. Moreover, the compound was found to trigger apoptosis in HL60 cells, inducing DNA fragmentation and caspase-3, -6, and -9 activations. The apoptsosis-induced by RT-04 is probably related to the diminished Bcl-2 expression, observed by RT-PCR, in HL60-treated cells. In vivo studies demonstrated that the RT-04 treatment (2.76 mg/kg given for three consecutive days) produces no significant toxic effects for bone marrow and spleen CFU-GM. However, higher doses (5.0 and 10 mg/kg) produced a dose-dependent reduction in the number of CFU-GM of RT-04-treated mice. These results suggest that RT-04 is able to induce apoptosis in HL60 cells by Bcl-2 expression down-modulation. Further studies are necessary to better clarify the effects of this compound on bone marrow normal cells.

Anandamide and NADA bi-directionally modulate presynaptic Ca2+ levels and transmitter release in the hippocampus

BACKGROUND AND PURPOSE

Inhibitory CB(1) cannabinoid receptors and excitatory TRPV(1) vanilloid receptors are abundant in the hippocampus. We tested if two known hybrid endocannabinoid/endovanilloid substances, N-arachidonoyl-dopamine (NADA) and anandamide (AEA), presynapticaly increased or decreased intracellular calcium level ([Ca(2+)](i)) and GABA and glutamate release in the hippocampus.

EXPERIMENTAL APPROACH

Resting and K(+)-evoked levels of [Ca(2+)](i) and the release of [(3)H]GABA and [(3)H]glutamate were measured in rat hippocampal nerve terminals.

KEY RESULTS

NADA and AEA per se triggered a rise of [Ca(2+)](i) and the release of both transmitters in a concentration- and external Ca(2+)-dependent fashion, but independently of TRPV(1), CB(1), CB(2), or dopamine receptors, arachidonate-regulated Ca(2+)-currents, intracellular Ca(2+) stores, and fatty acid metabolism. AEA was recently reported to block TASK-3 potassium channels thereby depolarizing membranes. Common inhibitors of TASK-3, Zn(2+), Ruthenium Red, and low pH mimicked the excitatory effects of AEA and NADA, suggesting that their effects on [Ca(2+)](i) and transmitter levels may be attributable to membrane depolarization upon TASK-3 blockade. The K(+)-evoked Ca(2+) entry and Ca(2+)-dependent transmitter release were inhibited by nanomolar concentrations of the CB(1) receptor agonist WIN55212-2; this action was sensitive to the selective CB(1) receptor antagonist AM251. However, in the low micromolar range, WIN55212-2, NADA and AEA inhibited the K(+)-evoked Ca(2+) entry and transmitter release independently of CB(1) receptors, possibly through direct Ca(2+) channel blockade.

CONCLUSIONS AND IMPLICATIONS

We report here for hybrid endocannabinoid/endovanilloid ligands novel dual functions which were qualitatively similar to activation of CB(1) or TRPV(1) receptors, but were mediated through interactions with different targets.

Toxicity of beta-amyloid in HEK293 cells expressing NR1/NR2A or NR1/NR2B N-methyl-D-aspartate receptor subunits

Neurotoxicity induced by beta-amyloid peptide (Abeta) involves glutamate toxicity, resulting from overactivation of N-methyl-D-aspartate (NMDA) receptors and elevation of intracellular calcium. However, the heterogeneity of the NMDA receptors, frequently composed of NR1 and NR2A-D subunits, has been less studied. Thus, we determined the contribution of NMDA receptor subtypes on Abeta(1-40) toxicity in HEK293 cells transiently expressing NR1/NR2A or NR1/NR2B subunits. Analysis of lactate dehydrogenase (LDH) release and trypan blue exclusion revealed an increase in Abeta(1-40) toxicity upon NR1/NR2A expression, compared to NR1/NR2B, indicating loss of plasma membrane integrity. Furthermore, Abeta(1-40) decreased intracellular ATP in cells expressing NR1/NR2A. MK-801 ((+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate), a noncompetitive NMDA receptor antagonist, partially prevented the decrease in cell viability and the energy impairment. These differences were not accounted for by the activation of caspases 2, 3, 8 and 9 or calpains or by DNA fragmentation, excluding the hypothesis of apoptosis. Functional NR1/NR2A and NR1/NR2B receptor subtypes were further evidenced by single-cell calcium imaging. Stimulation of NR1/NR2A receptors with NMDA/glycine revealed an increase in intracellular calcium in cells pre-exposed to Abeta(1-40). Opposite effects were observed upon activation of NR1/NR2B receptors. These results suggest that NR1/NR2A-composed NMDA receptors mediate necrotic cell death in HEK293 cells exposed to Abeta(1-40) through changes in calcium homeostasis.

Susceptibility of hippocampal neurons to Abeta peptide toxicity is associated with perturbation of Ca2+ homeostasis

Neuritic dystrophy, loss of synapses and neuronal death in the cerebral cortex and hippocampus are hallmarks of Alzheimer's disease. The aim of the present study was to investigate the differential susceptibility of cortical and hippocampal neurons to amyloid-beta (Abeta)-induced toxicity. For that, we have used primary neuronal cultures prepared from rat brain cortex and hippocampus which were treated with the synthetic peptides Abeta25-35 or Abeta1-40. Abeta-induced apoptotic cell death was analyzed by determining caspase-3-like activity. Neuritic dystrophy was evaluated by cobalt staining and MAP2 immunoreactivity. Perturbation of Ca(2+) homeostasis caused by exposure to Abeta was evaluated by determining basal cytosolic calcium levels in the whole neuronal population and by single cell calcium imaging under basal and KCl-depolarization conditions. Finally, levels of GluR2 subunit of glutamate AMPA (alpha-amino-3-hydroxy-5-methylisoxazole-4-proprionate) receptors were quantified by western blotting. Our results demonstrated that hippocampal neurons in culture are more susceptible than cortical neurons to Abeta-induced apoptosis and also that this mechanism involves the perturbation of Ca(2+) homeostasis. Accordingly, the exposure of hippocampal neurons to Abeta peptides decreases the protein levels of the GluR2 subunit of glutamate AMPA receptors that may be associated with a significant rise of cytosolic Ca(2+) concentration, leading to dendritic dystrophy and activation of apoptotic neuronal death.

Application of ultrafiltration in the pulp and paper industry: metals removal and whitewater reuse

In the pulp and paper industry, the water use minimization is a constant target. One way to reduce water use is to recycle the effluent in a closed-cycle concept. In paper mills, the main source of liquid effluent is the so-called whitewater, which is the excess water, originated from pulp stock dewatering and other fibre contaminated water. This research studied the reuse of paper mill whitewater after membrane ultrafiltration (UF) in the paper machine and in the pulp bleach plant of an integrated mill. Contaminant removal and flux behaviour of the UF system were evaluated. The treatment by ultrafiltration was technically feasible and the treated whitewater had good potential to be reused in some processes in the paper machine. The reuse of ultrafiltered whitewater in the bleaching plant was not recommended because of the high level of soluble calcium present in this stream. Therefore, a combined treatment of the whitewater using the principle of precipitation and ultrafiltration was proposed showing good results and enabling the use of the treated whitewater in the bleach plant.

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.

Increased density and synapto-protective effect of adenosine A2A receptors upon sub-chronic restraint stress

Stress initially causes adaptive changes in the brain and can lead to neurodegeneration if continuously present. Noxious brain conditions trigger the release of adenosine that can control brain function and neurodegeneration through inhibitory A(1) and facilitatory A(2A) receptors. We tested the effect of restraint stress on the density of adenosine receptors and their effect on the outcome of stress, focusing in a known affected region, the hippocampus. Sub-chronic restraint stress (6 h/day for 7 days) caused a parallel decrease of the density of A(1) receptors (15-20%) and an increase (near 250%) of A(2A) receptor density in rat hippocampal nerve terminals. This indicates that sub-chronic stress unbalances adenosine receptors, up-regulating A(2A) and down-regulating A(1) receptors. Sub-chronic stress did not cause hippocampal neurodegeneration but decreased the immunoreactivity (immunohistochemistry and Western blot) of a synaptic marker, synaptophysin. The blockade of A(2A) receptors with 7-(2-phenylethyl)-5-amino-2-(2-furyl)-pyrazolo-[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidine (0.05 mg/kg, daily i.p. injection) attenuated the loss of synaptophysin immunoreactivity observed in the hippocampus of rats subjected to sub-chronic restraint stress. This ability of A(2A) receptor antagonists to prevent the earliest stress-induced synaptic modifications provides a neurochemical and morphological correlate for the interest of A(2A) receptor antagonists to attenuate the burden of chronic stress.

Insulin Attenuates Diabetes-Related Mitochondrial Alterations: A Comparative Study

This study evaluated and compared the effect of insulin treatment on the status of brain, heart and kidney mitochondria isolated from 12-week streptozotocin (STZ)-induced diabetic rats versus STZ-diabetic animals treated with insulin during a period of 4 weeks. Mitochondria isolated from 12-week citrate (vehicle)-treated rats were used as control. Several mitochondrial parameters were evaluated: respiratory indexes (state 3 and 4 of respiration, respiratory control and ADP/O ratios), transmembrane potential, depolarization and repolarization levels, ATP, glutathione and coenzyme Q contents, production of hydrogen peroxide, superoxide dismutase, glutathione peroxidase and glutathione reductase activities and the ability of mitochondria to accumulate calcium. We observed that diabetes promoted a significant decrease in kidney and brain mitochondrial coenzyme Q9 content while this parameter was increased in heart mitochondria. Furthermore, diabetes induced a significant increase in hydrogen peroxide production in kidney mitochondria this effect being accompanied by a significant increase in glutathione peroxidase and reductase activities. Furthermore, brain mitochondria isolated from diabetic animals presented a lower ATP content and ability to accumulate calcium. In contrast, heart and kidney mitochondria presented a slight higher capacity to accumulate calcium. Insulin treatment normalized the levels of coenzyme Q9 and glutathione peroxidase and reductase activities and increased ATP content and the ability to accumulate calcium. Altogether these results suggest that insulin treatment attenuates diabetes-induced mitochondrial alterations protecting against the increase in oxidative stress and improving oxidative phosphorylation efficiency. In this line, insulin therapy, besides its well-known importance in the maintenance of glycemic control, may help to protect against mitochondrial dysfunction associated to several age-related disorders such as diabetes.

Results of the Brazilian Osteosarcoma Treatment Group Studies III and IV: prognostic factors and impact on survival

PURPOSE

To evaluate the impact of chemotherapy and surgery on the outcome of osteosarcoma (OS) of the extremities and to identify prognostic factors in Brazilian patients.

PATIENTS AND METHODS

A total of 225 patients with metastatic and nonmetastatic OS of the extremities were enrolled and assessed in two consecutive studies designed and implemented by the Brazilian Osteosarcoma Treatment Group.

RESULTS

The 5-year survival and event-free survival rates for the 209 assessable patients were 50.1% and 39%, respectively; for the 178 patients with nonmetastatic disease at diagnosis, the rates were 60.5% and 45.5%, respectively. The multivariate analysis showed that the following variables were associated with a shorter survival: metastases at diagnosis (P < .001), necrosis grades 1 and 2 (P = .046), and tumor size (P = .0071).

CONCLUSION

The overall 5- and 10-year survival rates were lower than the rates reported in North American and European trials. A pattern of advanced disease at diagnosis was often present, with a high proportion of patients having metastases (20.8%) and large tumor size (42.9%). However, these features were not necessarily associated with longer duration of prediagnostic symptoms. These findings were considered in the strategic planning of the current Brazilian cooperative study, with the aim of improving survival and quality of life of a large number of patients with OS.

Cytotoxicity of materials used in perforation repair tested using the V79 fibroblast cell line and the granulocyte-macrophage progenitor cells

AIM

To compare the cytotoxicity of materials used to repair perforations using permanent V79 fibroblasts and murine granulocyte-macrophage progenitor cells (CFU-GM).

METHODOLOGY

Set specimens from amalgam, glass-ionomer, SuperEBA, N-Rickert, MTA and gutta-percha were eluted with culture medium for 72 h and their cytotoxicities were assessed by incubating the extracts with V79 and bone marrow-derived progenitors for 24 h and 7 days, respectively. Cytotoxicity on V79 cells was judged using the total nucleic acid content (NAC), neutral red uptake (NRU) and reduction of the tetrazolium salt (MTT). The number of bone marrow CFU-GM colonies determined in clonal cultures stimulated with recombinant murine granulocyte-macrophage colony-stimulating factor was used to assess cytotoxicity to progenitor cells. Statistical analyses were conducted using the one-way analysis of variance and Tukey's test where appropriate.

RESULTS

All materials were cytotoxic in both cell systems; however, CFU-GM was more sensitive to the extracts than V79 cells. A similar rank order of toxicity was observed in V79 cells using the NAC and the MTT assays: glass-ionomer > N-Rickert congruent with SuperEBA > gutta-percha > amalgam congruent with MTA (P < 0.05). In contrast, the NRU test exhibited a lower sensitivity to MTA, gutta-percha and amalgam extracts. In the clonal culture assay, the toxicity was less pronounced in the presence of gutta-percha, SuperEBA and MTA. Similar cellular responses were found by placing the set specimens directly in the clonal culture dishes.

CONCLUSIONS

The sensitivity of toxicity depended on the choice of the endpoint and the cell-culture system. Nevertheless, MTA was ranked as the least cytotoxic cement in both cell systems.

Drugs of Abuse Induce Apoptotic Features in PC12 Cells

Drugs of abuse induce the release of dopamine in the central nervous system, particularly in the mesolimbic-mesocortical pathway. As dopamine may act as a neurotoxin, in this study, we analyzed the effects of the drugs of abuse, cocaine, heroin, and amphetamine, on the neurodegeneration of PC12 cells, a dopaminergic cell line, by evaluating the activity of caspase-3 and mitochondrial cytochrome c release. All the drugs were shown to induce caspase-3 activation, similarly to staurosporine, a classical inducer of apoptotic cell death. Furthermore, like staurosporine, the drugs of abuse induced a decrease in mitochondrial cytochrome c content, suggesting the involvement of the mitochondrial apoptotic pathway.

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.

Presynaptic kainate receptors are localized close to release sites in rat hippocampal synapses

The subsynaptic distribution of kainate receptors is still a matter of much debate given its importance to understand the way they influence neuronal communication. Here, we show that, in synapses of the rat hippocampus, presynaptic kainate receptors are localized within the presynaptic active zone close to neurotransmitter release sites. The activation of these receptors with low concentrations of agonists induces the release of [(3)H]glutamate in the absence of a depolarizing stimulus. Furthermore, this modulation of [(3)H]glutamate release by kainate is more efficient when compared with a KCl-evoked depolarization that causes a more than two-fold increase in the intra-terminal calcium concentration but no apparent release of [(3)H]glutamate, suggesting a direct receptor-mediated process. Using a selective synaptic fractionation technique that allows for a highly efficient separation of presynaptic, postsynaptic and non-synaptic proteins we confirmed that, presynaptically, kainate receptors are mainly localized within the active zone of hippocampal synapses where they are expected to be in a privileged position to modulate synaptic phenomena.

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.

Bystander Effect in Synergy to Anergy in Oral Tolerance of Blomia Tropicalis/Ovalbumin Murine Co-Immunization Model

Oral tolerance is an important approach in allergic diseases and murine model can provide useful information to improve its understanding and therapeutic measures. To address the influence of non-related allergen sensitization in immunized mice with the mite Blomia tropicalis (Bt) or ovalbumin (OVA) or with both Bt/OVA allergens. Furthermore, we sought to verify oral tolerance effect in the Bt/OVA co-immunization model. Mice sensitized with Bt and then exposed to OVA developed an enhanced IgE response to both allergens; contrariwise, this effect was not observed when OVA-sensitization was prior to Bt-sensitization. Co-injection of Bt and OVA led to a dominant IgE response towards OVA over Bt, which was not observed when co-immunization was performed with a 240-fold less amount of OVA. Induction of oral tolerance with OVA, prior to co-immunization, suppressed IgE response to both allergens, probably as a consequence of the increased levels of IFN-gamma found in these animals. The results evidenced that, depending on allergenic potential, new allergen exposure may exert an adjuvant effect to the first allergen used in the sensitization. The bystander suppression to non-related allergens through oral tolerance should be a useful mechanism to control sensitization to new allergens.

Mitochondrial dysfunction in autism spectrum disorders: a population-based study

A minority of cases of autism has been associated with several different organic conditions, including bioenergetic metabolism deficiency. In a population-based study, we screened associated medical conditions in a group of 120 children with autism (current age range 11y 5mo to 14y 4mo, mean age 12y 11mo [SD 9.6mo], male:female ratio 2.9:1). Children were diagnosed using Diagnostic and Statistical Manual of Mental Disorders criteria, the Autism Diagnostic Interview--Revised, and the Childhood Autism Rating Scale; 76% were diagnosed with typical autism and 24% with atypical autism. Cognitive functional level was assessed with the Griffiths scale and the Wechsler Intelligence Scale for Children and was in the normal range in 17%. Epilepsy was present in 19 patients. Plasma lactate levels were measured in 69 patients, and in 14 we found hyperlactacidemia. Five of 11 patients studied were classified with definite mitochondrial respiratory chain disorder, suggesting that this might be one of the most common disorders associated with autism (5 of 69; 7.2%) and warranting further investigation.

Different synaptic and subsynaptic localization of adenosine A2A receptors in the hippocampus and striatum of the rat

Adenosine A(2A) receptors are most abundant in the striatum where they control the striatopallidal pathway thus controlling locomotion. Extra-striatal A(2A) receptors are considerably less abundant but their blockade confers robust neuroprotection. We now have investigated if striatal and extra-striatal A(2A) receptors have a different neuronal location to understand their different functions. The binding density of the A(2A) antagonist, [(3)H]-7-(2-phenylethyl)-5-amino-2-(2-furyl)pyrazolo[4,3e][1,2,4]triazolo[1,5-c]pyrimidine ([(3)H]SCH 58261), was enriched in nerve terminals membranes (B(max)=103+/-12 fmol/mg protein) compared with total membranes (B(max)=29+/-4 fmol/mg protein) from the hippocampus, the same occurring with A(2A) receptor immunoreactivity. In contrast, there was no enrichment of [(3)H]SCH 58261 binding or A(2A) receptor immunoreactivity in synaptosomal compared with total membranes from the striatum. Further subcellular fractionation of hippocampal nerve terminals revealed that A(2A) receptor immunoreactivity was enriched in the active zone of presynaptic nerve terminals, whereas it was predominantly located in the postsynaptic density in the striatum, although a minority of striatal A(2A) receptors were located in the presynaptic active zone. These results indicate that A(2A) receptors in the striatum are not enriched in synapses in agreement with the preponderant role of A(2A) receptors in signal processing in striatopallidal neurons. In contrast, hippocampal A(2A) receptors are enriched in synapses, mainly in the active zone, in accordance with their role in controlling neurotransmitter release. This regional variation in the neuronal distribution of A(2A) receptors reinforces the care required to extrapolate our knowledge from striatal A(2A) receptors to other brain preparations.

Adenosine A1 and A2A receptors are co-expressed in pyramidal neurons and co-localized in glutamatergic nerve terminals of the rat hippocampus

Adenosine is a neuromodulator that controls neurotransmitter release through inhibitory A1 and facilitatory A2A receptors. Although both adenosine receptor-mediated inhibition and facilitation of glutamate release have been observed, it is not clear whether both A1 and A2A receptors are located in the same glutamatergic nerve terminal or whether they are located on different populations of these terminals. Thus, we have tested if single pyramidal glutamatergic neurons from the hippocampus simultaneously expressed A1 and A2A receptor mRNA and if A1 and A2A receptors were co-localized in hippocampal glutamatergic nerve terminals. Single cell PCR analysis of visually identified pyramidal neurons revealed the simultaneous presence of A1 and A2A receptor mRNA in four out 16 pyramidal cells possessing glutamatergic markers but not GABAergic or astrocytic markers. Also, A1 and A2A receptor immunoreactivities were co-localized in 26 +/- 4% of nerve terminals labeled with antibodies against vesicular glutamate transporters type 1 or 2, i.e. glutamatergic nerve terminals. This indicates that glutamatergic neurons in the hippocampus co-express A1 and A2A receptors and that these two receptors are co-localized in a subset of glutamatergic nerve terminals.

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.

Blomia tropicalis and Dermatophagoides pteronyssinus Mites Evoke Distinct Patterns of Airway Cellular Influx in Type I Hypersensitivity Murine Model

Murine models of hypersensitivity to allergens are useful tools for the evaluation of strategies to downmodulate IgE response. We sought to compare allergen inflammatory pulmonary response in previously sensitized mice orally administered with dust mites Blomia tropicalis (Bt) or Dermatophagoides pteronyssinus (Dp). Sensitized A/Sn mice fed with Bt or Dp showed a significant decrease in the IgE response compared to control-immunized mice. Bt-immunized mice demonstrated an accumulation of neutrophils in the bronchoalveolar lavage fluid, while Dp-immunized mice revealed an intense influx of eosinophils in the airway. Bt oral administration did not attenuate cell influx in the airway and Dp-fed mice showed a significant decrease of neutrophils and lymphocytes in the bronchoalveolar lavage fluid. These findings demonstrated that oral tolerance induction to Bt and Dp extract in sensitized mice decrease IgE response, but does not interfere in local inflammatory pulmonary response. The distinct profile of airway cellular infiltration between mites immunization suggest an interesting model to study allergic inflammation.

IgA response in serum and gut secretion in sensitized mice fed with the dust mite Dermatophagoides pteronyssinus extract

Induced oral tolerance to mucosal-exposed antigens in immunized animals is of particular interest for the development of immunotherapeutic approaches to human allergic diseases. This is a unique feature of mucosal surfaces which represent the main contact interface with the external environment. However, the influence of oral tolerance on specific and natural polyreactive IgA antibodies, the major defense mechanism of the mucosa, is unknown. We have shown that oral administration of an extract of the dust mite Dermatophagoides pteronyssinus (Dp) to primed mice caused down-regulation of IgE responses and an increase in tumor growth factor-beta secretion. In the present study, we observed that primed inbred female A/Sn mice (8 to 10 weeks old) fed by gavage a total weight of 1.0-mg Dp extract on the 6th, 7th and 8th days post-immunization presented normal secretion of IL-4 and IL-10 in gut-associated lymphoid tissue and a decreased production of interferon gamma induced by Dp in the draining lymph nodes (13,340 +/- 3,519 vs 29,280 +/- 2,971 pg/ml). Mice fed the Dp extract also showed higher levels of serum anti-Dp IgA antibodies and an increase of IgA-secreting cells in mesenteric lymph nodes (N = 10), reflecting an increase in total fecal IgA antibodies (N = 10). The levels of secretory anti-Dp IgA antibodies increased after re-immunization regardless of Dp extract feeding. Oral tolerance did not interfere with serum or secretory IgA antibody reactivity related to self and non-self antigens. These results suggest that induction of oral tolerance to a Dp extract in sensitized mice triggered different regulatory mechanisms which inhibited the IgE response and stimulated systemic and secretory IgA responses, preserving the natural polyreactive IgA antibody production.

Effect of streptozotocin-induced diabetes on rat brain mitochondria

This study evaluated several parameters related to mitochondrial function and oxidative stress in streptozotocin (STZ)-treated rats, a model of type 1 diabetes. For this purpose, the respiratory indexes (RCR and ADP/O ratio), mitochondrial transmembrane potential (DeltaPsim), repolarization lag phase, repolarization level, mitochondrial enzymatic activities, ATP and malondialdehyde (MDA) levels, reduced glutathione (GSH), vitamin E and cardiolipin contents were determined in rat brain mitochondria isolated after 4 and 9 weeks after STZ treatment. Brain mitochondria isolated from citrate (vehicle)-treated Wistar rats were used as control. We observed that STZ-induced diabetes did not substantially affect brain mitochondrial function. Instead, 4-week diabetic rats presented higher mitochondrial respiratory chain enzymatic activities, especially succinate-cytochrome C reductase activity, compared to 4-week control rats. In 9-week diabetic rats, only a significant decrease in cardiolipin content was observed; however, a significant increase in mitochondrial GSH content occurred. All other parameters analysed remained statistically unchanged. From these results, we conclude that STZ-induced diabetes did not promote brain mitochondrial dysfunction, suggesting that oxidative stress associated with type 1 diabetes is not directly related to mitochondrial dysfunction, but probably is related to extramitochondrial factor(s).

Aluminium-induced impairment of Ca2+ modulatory action on GABA transport in brain cortex nerve terminals

The gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in vertebrate CNS. At GABAergic synapses, a high-affinity transporter exists, which is responsible for GABA reuptake and release during neurotransmission. GABA transporter activity depends on the phosphorylation/dephosphorylation state, being modulated by Ca(2+)/calmodulin-dependent protein phosphatase 2B (calcineurin). Aluminium is known to interfere with the Ca(2+)/calmodulin signalling pathway. In this work, we investigate the action of aluminium on GABA translocation mediated by the high-affinity transporter, using synaptic plasma membrane (SPM) vesicles and synaptosomes isolated from brain cortex. Aluminium completely relieved Ca(2+) downregulation of GABA transporter, when mediating uptake or release. Accordingly, aluminium inhibited Ca(2+)/calmodulin-dependent calcineurin activity present in SPM, in a concentration-dependent manner. The deleterious action of aluminium on the modulation of GABA transport was ascertained by comparative analysis of the aluminium effect on GABA uptake and release, under conditions favouring SPM dephosphorylation (presence of intracellular micromolar Ca(2+)) or phosphorylation (absence of Ca(2+) and/or presence of W-7, a selective calmodulin antagonist). In conclusion, aluminium-induced relief of Ca(2+) modulatory action on GABA transporter may contribute significantly to modify GABAergic signalling during neurotoxic events in response to aluminium exposure.

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.

Oral tolerance induction to Dermatophagoides pteronyssinus and Blomia tropicalis in sensitized mice: occurrence of natural autoantibodies to immunoglobulin E

BACKGROUND

The dust mites Dermatophagoides pteronyssinus (Dp) and Blomia tropicalis (Bt) are important sources of indoor allergens in tropical and subtropical countries. Murine models allow the analysis of the immune response and regulation of IgE production to Dp and Bt allergens. Oral tolerance induces unresponsiveness in naive animals, but its application in sensitized animals can provide useful information to improve allergy therapy.

OBJECTIVE

To study the profile of IgE and IgG subclasses antibody upon oral administration with Bt and Dp extract in previously sensitized mice. Further, the occurrence of autoantibodies IgG anti-IgE in the immunization and in the oral tolerance was investigated.

METHODS

A/Sn mice were immunized with Bt or Dp extract in alum, orally administrated with 0.25 mg of Bt or Dp extract or PBS at the 6th, 7th and 8th days after immunization and boosted twice with their respective allergens. To analyse the mice groups, specific IgE antibodies were measured by passive anaphylaxis reaction and specific IgG subclasses and anti-IgE IgG autoantibody by ELISA assay.

RESULTS

IgE levels were markedly increased in Bt-immunized mice compared with Dp-immunized mice. A distinct profile of the specific isotypes was verified in Bt-immunized mice with a preferential production of IgG3 and IgA antibodies, whereas Dp-immunized mice developed high titres of anti-Dp IgG1, IgG2a and IgG2b antibodies. The antigen feeding inhibited IgE response in both fed-mice groups but only Dp-fed mice presented decreased levels of IgG antibodies. Free anti-IgE IgG autoantibodies were detected mainly in the Dp-immunization and they correlated with the antibody isotypes found against the allergen.

CONCLUSIONS

This is the first time that the murine-type I hypersensitivity is employed to study Bt-immunization, showing a marked IgE production, associated with IgG response, which is at least in part driven by T-independent antigens. The oral tolerance protocol in previously sensitized animals was able to down-modulate IgE response and points out this route as a strategy for allergy therapy.

Toxic effects of opioid and stimulant drugs on undifferentiated PC12 cells

Cell death and reactive oxygen species production have been suggested to be involved in neurodegeneration induced by the drugs of abuse. In this study we analyze the toxicity of the following drugs of abuse: heroin, morphine, d-amphetamine, and cocaine in undifferentiated PC12 cells, used as dopaminergic neuronal models. Our data show that opioid drugs (heroin and morphine) are more toxic than stimulant drugs (d-amphetamine and cocaine). Toxic effects induced by heroin are associated with a decrease in intracellular dopamine, an increase in DOPAC levels, and the formation of ROS, whereas toxic effects induced by amphetamine are associated with a decrease in intracellular dopamine and in ATP/ADP levels. In contrast with cocaine, both amphetamine and heroin induced features of apoptosis. The data suggest that the death of cultured PC12 cells induced by the drugs of abuse is correlated with a decrease in intracellular dopamine levels, which can be associated with an increased dopamine turnover and oxidative cell injury.

Influence of maternal murine immunization with Dermatophagoides pteronyssinus extract on the type I hypersensitivity response in offspring

BACKGROUND

Maternal exposure to environmental ubiquitous allergens could exert an influence on the newborn's immune repertoire and the later development of allergy. The aim of this study was to investigate the effects of maternal immunization with Dermatophagoides pteronyssinus (Dp) on the hypersensitivity response and IgG subclass production in offspring using a murine model.

METHODS

A/Sn mice were immunized with Dp before mating with normal A/Sn males. Diaplacental serum samples were collected from newborn mice delivered by cesarean section, and maternal milk samples were extracted from the stomachs of newborn mice. Groups of offspring 25 or 45 days old were Dp immunized and boosted on the 10th day after sensitization. The animals were bled 7 days after the booster.

RESULTS

High levels of anti-Dp IgG subclasses - mainly IgG1, but also IgG2a and IgG2b - were transmitted by immunized mice via the placenta to the offspring. In the milk from immunized mothers, significant levels of anti-Dp IgG subclasses and anti-Dp IgM and IgA antibodies were detected. Moreover, the increase in total IgA antibodies in the milk of the immunized females correlated with a significantly increased level of TGF-beta1. TGF-beta2 levels were markedly higher than the beta1 isoform in the milk, although no difference was observed between the groups. When offspring from immunized mothers were sensitized at 25 days, a significant decrease in total and anti-Dp IgE antibodies as well as total and anti-Dp IgG1, IgG2a and IgG2b subclasses was observed compared to normal female offspring, whereas when offspring were sensitized at 45 days, both offspring groups showed similar levels of IgE and IgG subclasses.

CONCLUSIONS

Our study showed that maternal immunization with Dp promotes the transference of specific antibodies and/or TGF-beta, which can negatively modulate the allergic response in offspring, and suggests that maternal preexposure to allergen before mating can protect mice during the early phase.

Oral tolerance induction in dermatophagoides pteronyssinus-sensitized mice induces inhibition of IgE response and upregulation of TGF-beta secretion

Oral antigen administration induces peripheral tolerance in naive animals. Studies of oral tolerance induction in sensitized mice have clinical relevance as a strategy to modulate allergy. In this study, the A/Sn mice sensitized with extract of Dermatophagoides pteronyssinus (Dp) and submitted to oral Dp administration showed a marked decrease in IgE anti-Dp antibody production compared with sensitized phosphate-buffered saline (PBS)-fed mice. T cells from Dp-fed mice cocultured with spleen cells from PBS-fed mice were able to inhibit IgE anti-Dp antibody production and did not interfere in IgG1 antibody levels. The analysis of cytokine profile after Dp feeding showed a significant decrease in interleukin-4 (IL-4), IL-5, and IL-13 antigen-induced secretion levels by spleen cells, without shifting to IL-2 and interferon-gamma (IFN-gamma) production. Both transforming growth factor-beta (TGF-beta) baseline and TGF-beta antigen-stimulated levels were increased in Dp-fed mice. The effects of regulatory cytokines on anti-Dp IgE antibody production were investigated in vitro. The addition of recombinant TGF-beta (rTGF-beta) to spleen cell cultures stimulated by Dp inhibited IgE antibody secretion in both mouse groups. Neutralizing antibodies to IL-4, but not anti-TGF-beta, induced a marked inhibition of IgE production. Therefore, a negative modulatory effect on IgE response by inhibition of the axis Th2 was observed in sensitized Dp-fed mice, possibly mediated by induction of regulatory cytokines.

Lipid peroxidation and aluminium effects on the cholinergic system in nerve terminals

In the present study, we analyzed how aluminium and oxidative stress induced by ascorbate/Fe(2+) affect the mechanisms related with the cholinergic system in a crude synaptosomal fraction isolated from rat brain. [(3)H]Choline uptake, [(3)H]acetylcholine release, membrane potential and Na(+)/K(+)-ATPase activity were determined in the presence or in the absence of aluminium in control conditions and in the presence of ascorbate (0.8 mM)/Fe(2+) (2.5 micro M). The extent of lipid peroxidation was measured by quantifying thiobarbituric acid reactive substances (TBARS). Under oxidizing conditions aluminium increased the formation of TBARS by about 30%, but was without effect when the synaptosomal preparation was incubated in the absence of oxidants. Additionally, aluminium potentiated the inhibition of the high-affinity [(3)H]choline uptake observed following lipid peroxidation and had the same effect on the Na(+)/K(+)-ATPase activity. [(3)H]Acetylcholine release induced by 4-aminopyridine, and membrane potential were not significantly affected under oxidizing conditions, either in the absence or in the presence of aluminium. We can conclude that aluminium, by potentiating lipid peroxidation, affects the uptake of choline in nerve endings. This effect, occurring during brain oxidative injury, might contribute to the cholinergic dysfunction and neuronal cell degeneration known to occur in Alzheimer's disease.

Antioxidant effect of flavonoids after ascorbate/Fe2+-induced oxidative stress in cultured retinal cells11Abbreviations: BME, basal medium of Eagle; DCFH2, 2′,7′-dichlorodihydrofluorescein; LDH, lactate dehydrogenase; PC, partition coefficient; Rf, retardation factor; ROS, reactive oxygen species; TBA, thiobarbituric acid; and TBARS, thiobarbituric acid-reactive substances

In this study, we investigated the structure-activity relationship of four flavonoids, i.e. eriodictyol, luteolin, quercetin, and taxifolin, in cultured retinal cells after ascorbate/Fe(2+)-induced oxidative stress. The relative order of antioxidant efficacy, determined by the thiobarbituric acid method, was the following: eriodictyol > quercetin > luteolin > taxifolin. Upon preincubation, the flavonoids were also effective in reducing the extent of lipid peroxidation. Oxidative stress, determined by the changes in fluorescence of 2',7'-dichlorodihydrofluorescein, was also decreased in the presence of the flavonoids, showing the following order of antioxidant efficacy: eriodictyol > taxifolin approximately quercetin > luteolin. Ascorbate/Fe(2+)-induced oxidative stress or incubation in the presence of the flavonoids did not significantly affect the viability of retinal cells. We also evaluated the degree of membrane partition of the flavonoids. In this system, the results strongly suggest that the higher antioxidant activity of the flavonoids is not correlated with the presence of a double bond at C(2)-C(3) and/or a hydroxyl group at C(3) on the C ring, but rather may depend on the capacity to inhibit the production of reactive oxygen species to interact hydrophobically with membranes. Eriodictyol was shown to be the most efficient antioxidant in protecting against oxidative stress induced by ascorbate/Fe(2+) in the retinal cells.