Lipocalin-2 regulates adult neurogenesis and contextual discriminative behaviours.

In the adult mammalian brain, newborn granule cells are continuously integrated into hippocampal circuits, and the fine-tuning of this process is important for hippocampal function. Thus, the identification of factors that control adult neural stem cells (NSCs) maintenance, differentiation and integration is essential. Here we show that the deletion of the iron trafficking protein lipocalin-2 (LCN2) induces deficits in NSCs proliferation and commitment, with impact on the hippocampal-dependent contextual fear discriminative task. Mice deficient in LCN2 present an increase in the NSCs population, as a consequence of a G0/G1 cell cycle arrest induced by increased endogenous oxidative stress. Of notice, supplementation with the iron-chelating agent deferoxamine rescues NSCs oxidative stress, promotes cell cycle progression and improves contextual fear conditioning. LCN2 is, therefore, a novel key modulator of neurogenesis that, through iron, controls NSCs cell cycle progression and death, self-renewal, proliferation and differentiation and, ultimately, hippocampal function.

Dual role of histamine on microglia-induced neurodegeneration.

Several hypotheses have been raised about the dual role of histamine in neurological disorders, and evidences have shown its crucial involvement in the modulation of microglia-mediated neuroinflammation. Previously, we reported that the administration of histamine induces a deleterious effect by promoting a pro-inflammatory phenotype on microglia that in turn compromises dopaminergic neuronal survival. Contrary, under lipopolysaccharide challenge, histamine inhibits the injurious effect of microglia-mediated inflammation, protecting dopaminergic neurons, suggesting that the modulation of microglial activity is dependent on the environmental context. Thus, histamine and/or histamine receptor agonists may serve to develop new therapeutic approaches to overcome neurodegenerative disorders.

MicroRNA-124 loaded nanoparticles enhance brain repair in Parkinson's disease.

Modulation of the subventricular zone (SVZ) neurogenic niche can enhance brain repair in several disorders including Parkinson's disease (PD). Herein, we used biocompatible and traceable polymeric nanoparticles (NPs) containing perfluoro-1,5-crown ether (PFCE) and coated with protamine sulfate to complex microRNA-124 (miR-124), a neuronal fate determinant. The ability of NPs to efficiently deliver miR-124 and prompt SVZ neurogenesis and brain repair in PD was evaluated. In vitro, miR-124 NPs were efficiently internalized by neural stem/progenitors cells and neuroblasts and promoted their neuronal commitment and maturation. The expression of Sox9 and Jagged1, two miR-124 targets and stemness-related genes, were also decreased upon miR-124 NP treatment. In vivo, the intracerebral administration of miR-124 NPs increased the number of migrating neuroblasts that reached the granule cell layer of the olfactory bulb, both in healthy and in a 6-hydroxydopamine (6-OHDA) mouse model for PD. MiR-124 NPs were also able to induce migration of neurons into the lesioned striatum of 6-OHDA-treated mice. Most importantly, miR-124 NPs proved to ameliorate motor symptoms of 6-OHDA mice, monitored by the apomorphine-induced rotation test. Altogether, we provide clear evidences to support the use of miR-124 NPs as a new therapeutic approach to boost endogenous brain repair mechanisms in a setting of neurodegeneration.

Retinoic acid-loaded polymeric nanoparticles enhance vascular regulation of neural stem cell survival and differentiation after ischaemia.

Stroke is one of the leading causes of death and disability worldwide. However, current therapies only reach a small percentage of patients and may cause serious side effects. We propose the therapeutic use of retinoic acid-loaded nanoparticles (RA-NP) to safely and efficiently repair the ischaemic brain by creating a favourable pro-angiogenic environment that enhances neurogenesis and neuronal restitution. Our data showed that RA-NP enhanced endothelial cell proliferation and tubule network formation and protected against ischaemia-induced death. To evaluate the effect of RA-NP on vascular regulation of neural stem cell (NSC) survival and differentiation, endothelial cell-conditioned media (EC-CM) were collected. EC-CM from healthy RA-NP-treated cells reduced NSC death and promoted proliferation while EC-CM from ischaemic RA-NP-treated cells decreased cell death, increased proliferation and neuronal differentiation. In parallel, human endothelial progenitor cells (hEPC), which are part of the endogenous repair response to vascular injury, were collected from ischaemic stroke patients. hEPC treated with RA-NP had significantly higher proliferation, which further highlights the therapeutic potential of this formulation. To conclude, RA-NP protected endothelial cells from ischaemic death and stimulated the release of pro-survival, proliferation-stimulating factors and differentiation cues for NSC. RA-NP were shown to be up to 83-fold more efficient than free RA and to enhance hEPC proliferation. These data serve as a stepping stone to use RA-NP as vasculotrophic and neurogenic agents for vascular disorders and neurodegenerative diseases with compromised vasculature.

Cellular response of the blood-brain barrier to injury: Potential biomarkers and therapeutic targets for brain regeneration.

Endothelial cells are the main component of the blood-brain barrier (BBB), a vital structure for maintaining brain homeostasis that is seriously disrupted in various neurological pathologies. Therefore, vascular-targeted therapies may bring advantages for the prevention and treatment of brain disorders. In this sense, novel methods to identify and evaluate endothelial damage have been developed and include the detection of circulating endothelial cells, endothelial progenitor cells, endothelial microparticles and exosomes. These cells and cellular structures have been documented in numerous diseases, and increasingly in neurodegenerative disorders, which have led many to assume that they can either be possible biomarkers or tools of repair. Therefore, the purpose of this review is to discuss available data on BBB endothelial damage occurring in two pathologies of the central nervous system, Alzheimer's disease and stroke, which exemplify conditions where chronic and acute vascular damage occur, respectively. The ultimate goal is to identify useful biomarkers and/or therapeutic tools in the healthy and diseased brain that can be used for the treatment of neurodegenerative diseases where BBB permeability and integrity are impaired.

Interaction between neuropeptide Y (NPY) and brain-derived neurotrophic factor in NPY-mediated neuroprotection against excitotoxicity: a role for microglia.

The neuroprotective effect of neuropeptide Y (NPY) receptor activation was investigated in organotypic mouse hippocampal slice cultures exposed to the glutamate receptor agonist alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA). Exposure of 2-week-old slice cultures, derived from 7-day-old C57BL/6 mice, to 8 microm AMPA, for 24 h, induced degeneration of CA1 and CA3 pyramidal cells, as measured by cellular uptake of propidium iodide (PI). A significant neuroprotection, with a reduction of PI uptake in CA1 and CA3 pyramidal cell layers, was observed after incubation with a Y(2) receptor agonist [NPY(13-36), 300 nm]. This effect was sensitive to the presence of the selective Y(2) receptor antagonist (BIIE0246, 1 microm), but was not affected by addition of TrkB-Fc or by a neutralizing antibody against brain-derived neurotrophic factor (BDNF). Moreover, addition of a Y(1) receptor antagonist (BIBP3226, 1 microm) or a NPY-neutralizing antibody helped to disclose a neuroprotective role of endogenous NPY in CA1 region. Cultures exposed to 8 microm AMPA for 24 h, displayed, as measured by an enzyme-linked immunosorbent assay, a significant increase in BDNF. In such cultures there was an up-regulation of neuronal TrkB immunoreactivity, as well as the presence of BDNF-immunoreactive microglial cells at sites of injury. Thus, an increase of AMPA-receptor mediated neurodegeneration, in the mouse hippocampus, was prevented by neuroprotective pathways activated by NPY receptors (Y(1) and Y(2)), which can be affected by BDNF released by microglia and neurons.

Inflammation and neurogenesis in temporal lobe epilepsy.

The aim of the present review is to discuss the evidence supporting the hypothesis that inflammation and neurogenesis play an important role in temporal lobe epilepsy (TLE) and to examine whether possible strategies that involve the pharmacological manipulation of inflammation/neurogenesis can lead to the development of novel approaches for the treatment of epilepsy. Since it is not yet clear whether the neuron-glia response obtained in this pathology is a secondary effect of an aggressive inflammation or if it is somehow related to the cause of the epileptic condition, with the present review we guide the readers through the complex and ambiguous crosstalk between neuroimmunology and epilepsy.

[Cardiovascular morbidity in children with human immunodeficiency virus infection]. / Morbilidade cardiovascular em crianças com infecção pelo vírus da imunodeficiência humana.

UNLABELLED: Abnormalities of cardiovascular structure and function have been described among children with human immunodeficiency virus (HIV). In order to evaluate their occurrence and clinical predictors, 32 children infected with HIV, aged three months to 13 years (mean age = 3.11 +/- 3.51 years) were studied. Perinatal transmission was identified in 90% of the children. Twenty-two patients (pts) (69%) had symptoms, nine being moderately symptomatic and eight severely symptomatic. Fourteen pts had immunological disturbances and eight of them were severely immunosuppressed. Twenty-eight pts (88%) had HIV-1 infection and 6 recent Ebstein-Barr virus coinfection. Nineteen were on zidovudine and 14 on intravenous immunoglobulin treatment. Nineteen cardiovascular abnormalities were found in 15 pts (47%): 11 cases of pulmonary hypertension by echocardiographic criteria (eight of them had interstitial lung infiltrates seen on chest X-ray) and four cases of left ventricular dysfunction requiring anticongestive therapy. Other abnormalities were: patent ductus arteriosus, septal hypertrophy, mitral valve prolapse and pericardial effusion (one case each). Surface ECG displayed right ventricular hypertrophy in four pts, left ventricular hypertrophy in one patient and unspecific ST-T wave changes in two pts. Fourteen pts (44%) had sinus tachycardia with mean heart rate above the 95th percentile on 24-hour Holter monitoring. CONCLUSIONS: Cardiovascular abnormalities are frequent among children with HIV-1 infection in late stages; pulmonary hypertension is the most frequently found cardiovascular anomaly and seems to be related to either chronic or recurrent respiratory disease; cardiological follow-up is recommended for HIV-infected children.

Angiographically assessed coronary collateral circulation increases vulnerability to myocardial ischemia during vasodilator stress testing.

In patients with a major coronary vessel occluded, the presence of good coronary collateral circulation increases vulnerability to myocardial ischemia induced by pharmacologic coronary vasodilation. The presence of good collaterals results in a greater frequency, severity, and extent of dipyridamole-induced regional left ventricular dysfunction, consistent with the hypothesis of angiographically assessed collaterals facilitating "steal phenomena" during dipyridamole-induced coronary vasodilation.

[Prenatal diagnosis of congenital cardiomyopathies. Current reality in the south of the country]. / Diagnóstico pré-natal das cardiopatias congénitas. Realidade actual no sul do país.

In order to make an actual perspective about prenatal diagnosis of congenital heart disease in the area of influence of our department, a prospective study including 948 fetus and 185 newborn was done, 348 fetus and 20 newborn evaluated during 1993 (group I) and the remaining during 1994 (group II). In both groups indications for fetal echocardiography were mainly maternal (18%) and familiar (14%) factors, but occurrence of CHD were respectively 2% and 0% for them. Fetal factors for echocardiography account for 7%, namely arrhythmias (7%) and obstetric suspicion of CHD (6%), but occurrence of CHD was respectively 13% and 32% for group I and 36% and 48% for group II. In the newborn with serious CHD, risk factors could be identified in 30% in group I and 36% in group II, being respectively 15% and 7% referred for fetal echocardiography. It is concluded that although a rise in the number of fetus evaluated and a better obstetric accuracy have occurred, the rate of prenatal diagnosis of CHD is still very low, pointing to necessity of continuing our actual policy of teaching and spreading this area, specially in the primary health care units.

[Fetal arrhythmia. A case load of 4 years and a half]. / Arritmias fetais. Casuística de quatro anos e meio.

In a 4 1/2 year period fetal, echocardiographic studies were performed on 1600 fetuses. In 55 with arrhythmia, 44 had supraventricular ectopic beats, resolved in all, and none had heart disease. Sustained arrhythmias occurred in 11 fetuses. Atrial flutter was present in 3 all with heart disease (Ebstein disease, right atrial tumour and WPW diagnosed after birth). Another 3 fetuses had supraventricular tachycardia (SVT), all with a normal heart. In the bradycardia group, 2 had complete heart block (CHB) associated with AVSD; 2 sinus bradycardia and one had non conducted atrial ectopic beats. Digoxin was the first choice drug for tachyarrhythmia therapy; association with Verapamil, Flecainide, Quinidine and Procainamide was used in 4 of the 6. One fetus with CHB received Orciprenaline with no results. Atrial flutter resolved or improved; in SVT 2 fetuses converted to sinus rhythm and one died in utero. All fetuses with CHB died in cardiac failure. Mortality was 27% (3 cases) in utero and global 36%. In our experience most fetal arrhythmias (90%) were transitory ectopic beats or non lasting bradycardia in normal heart and did not trigger other kinds of arrhythmias. In sustained arrhythmias, heart failure and heart disease had a negative effect on prognosis.

[Inflammatory pseudo tumor of the bladder (in a 6-month-old girl)]. / Pseudo tumor inflamatório da bexiga (em menina de 6 meses de idade).

We describe the clinical case of a six-month old female child, who presented an intra-vesical mass as a sequence of urinary tract infection. After surgical resection the histopathological study was consistent with the diagnosis of inflammatory pseudotumor of the bladder.

[The pathogen spectrum and its resistance behavior in children with urinary tract infections in Angola]. / Zum Erregerspektrum und seinem Resistenzverhalten bei Kindern mit Harnwegsinfektionen in Angola.

In 225 children (135 boys, 90 girls) suffering from clinical relevant urinary tract infection the bacterial spectrum and resistance behaviour to routinely used antibiotics were evaluated. In 65.4% of the patients a significant bacteriuria was found: E. coli (34.6%), proteus (22.3%), klebsiella (14.6%), citrobacter (9.2%), enterobacter (5.4%) and pseudomonas (5.4%). In testing a high resistance of bacterias to trimethoprim/sulfamethoxazol, ampicillin, and gentamycin was found, whereas good susceptibility was found to nitrofurantoin and nalidixin acid.