Molecular mechanisms of neurogenic aging in the adult mouse subventricular zone

In the adult rodent brain, the continuous production of new neurons by neural stem/progenitor cells (NSPCs) residing in specialized neurogenic niches and their subsequent integration into pre-existing cerebral circuitries supports odour discrimination, spatial learning, and contextual memory capabilities. Aging is recognized as the most potent negative regulator of adult neurogenesis. The neurogenic process markedly declines in the aged brain, due to the reduction of the NSPC pool and the functional impairment of the remaining NSPCs. This decline has been linked to the progressive cognitive deficits of elderly individuals and it may also be involved in the onset/progression of neurological disorders. Since the human lifespan has been dramatically extended, the incidence of age-associated neuropsychiatric conditions in the human population has increased. This has prompted efforts to shed light on the mechanisms underpinning the age-related decline of adult neurogenesis, whose knowledge may foster therapeutic approaches to prevent or delay cognitive alterations in elderly patients. In this review, we summarize recent progress in elucidating the molecular causes of neurogenic aging in the most abundant NSPC niche of the adult mouse brain: the subventricular zone (SVZ). We discuss the age-associated changes occurring both in the intrinsic NSPC molecular networks and in the extrinsic signalling pathways acting in the complex environment of the SVZ niche, and how all these changes may steer young NSPCs towards an aged phenotype

Use of the KlADH3 promoter for the quantitative production of the murine PDE5A isoforms in the yeast Kluyveromyces lactis

Background: Phosphodiesterases (PDE) are a superfamily of enzymes that hydrolyse cyclic nucleotides (cAMP/ cGMP), signal molecules in transduction pathways regulating crucial aspects of cell life. PDEs regulate the intensity and duration of the cyclic nucleotides signal modulating the downstream biological efect. Due to this critical role associated with the extensive distribution and multiplicity of isozymes, the 11 mammalian families (PDE1 to PDE11) constitute key therapeutic targets. PDE5, one of these cGMP-specifc hydrolysing families, is the molecular target of several well known drugs used to treat erectile dysfunction and pulmonary hypertension. Kluyveromyces lactis, one of the few yeasts capable of utilizing lactose, is an attractive host alternative to Saccharomyces cerevisiae for heterologous protein production. Here we established K. lactis as a powerful host for the quantitative production of the murine PDE5 isoforms. Results: Using the promoter of the highly expressed KlADH3 gene, multicopy plasmids were engineered to produce the native and recombinant Mus musculus PDE5 in K. lactis. Yeast cells produced large amounts of the purifed A1, A2 and A3 isoforms displaying Km, Vmax and Sildenafl inhibition values similar to those of the native murine enzymes. PDE5 whose yield was nearly 1 mg/g wet weight biomass for all three isozymes (30 mg/L culture), is well tolerated by K. lactis cells without major growth defciencies and interferences with the endogenous cAMP/cGMP signal transduction pathways. Conclusions: To our knowledge, this is the frst time that the entire PDE5 isozymes family containing both regulatory and catalytic domains has been produced at high levels in a heterologous eukaryotic organism. K. lactis has been shown to be a very promising host platform for large scale production of mammalian PDEs for biochemical and structural studies and for the development of new specifc PDE inhibitors for therapeutic applications in many pathologies

Thermal behaviour of Al-rich tobermorite

The tobermorite supergroup is composed by a number of calcium-silicate-hydrate (C-S-H) minerals characterized by different hydration states and sub-cell symmetries. Taking into account their basal spacing, closely related to the hydration state, phases having a 14 Å (plombierite), 11 Å (tobermorite, kenotobermorite, and clinotobermorite), and 9 Å (riversideite) basal spacing have been described. Tobermorite and kenotobermorite belong to the so-called tobermorite group and differ for their thermal behaviour which can be "normal" (the phase shrinks to a 9 Å phase at 300 °C) or "anomalous" (the phase preserves its 11 Å basal spacing at 300 °C). Specimens of Al-rich tobermorite from Montalto di Castro and Vallerano, Latium, Central Italy, showing a "normal" thermal behaviour, were studied in order to describe the transition from the 11 Å to the 9 Å phase by means of thermogravimetric-differential scanning calorimetry (TG-DSC) analyses as well as in situ and ex situ X-ray diffraction experiments. The TG-DSC analyses showed a continuous mass loss from 100 °C up to 700 °C, with different mass loss gradients between 100 °C up to 300 °C and between 300 °C up to 700 °C, corresponding to the dehydration of tobermorite and dehydroxylation of "tobermorite 9 A", respectively. Above 700 °C, "tobermorite 9 Å" is replaced by wollastonite. The X-ray powder diffraction data were collected at the GILDA beamline of the ESRF, Grenoble, France, from room temperature up to ca. 840 °C. Tobermorite is completely replaced by the 9 A phase at ca. 300 °C, whereas the latter is transformed into wollastonite at ca. 700 °C. The transition from the 11 Å to the 9 Å phase seems to be favoured by the transient appearance of a clinotobermorite-like compound

Molecular signatures of the aging brain: finding the links between genes and phenotypes

Aging is associated with cognitive decline and increased vulnerability to neurodegenerative diseases. The progressive extension of the average human lifespan is bound to lead to a corresponding increase in the fraction of cognitively impaired elderly individuals among the human population, with an enormous societal and economic burden. At the cellular and tissue levels, cognitive decline is linked to a reduction in specific neuronal subpopulations, a widespread decrease in synaptic plasticity and an increase in neuroinflammation due to an enhanced activation of astrocytes and microglia, but the molecular mechanisms underlying these functional changes during normal aging and in neuropathological conditions remain poorly understood. In this review, we summarize very recent and outstanding progress in elucidating the molecular changes associated with cognitive decline through the genome-wide profiling of aging brain cells at different molecular levels (genomic, epigenomic, transcriptomic, proteomic). We discuss how the correlation of different molecular and phenotypic traits driven by mathematical and computational analyses of large datasets has led to the prediction of key molecular nodes of neurodegenerative pathways, and provide a few examples of candidate regulators of cognitive decline identified with these approaches. Furthermore, we highlight the dysregulation of the synaptic transcriptome in neuronal cells and of the inflammatory transcriptome in glial cells as some of the key events during normal and neuropathological human brain aging

The Role of Adjunctive Therapies in Septic Shock by Gram Negative MDR/XDR Infections

Patients with septic shock by multidrug resistant microorganisms (MDR) are a specific sepsis population with a high mortality risk. The exposure to an initial inappropriate empiric antibiotic therapy has been considered responsible for the increased mortality, although other factors such as immune-paralysis seem to play a pivotal role. Therefore, beyond conventional early antibiotic therapy and fluid resuscitation, this population may benefit from the use of alternative strategies aimed at supporting the immune system. In this review we present an overview of the relationship between MDR infections and immune response and focus on the rationale and the clinical data available on the possible adjunctive immunotherapies, including blood purification techniques and different pharmacological approaches

Purpura Fulminans and Septic Shock due to Capnocytophaga Canimorsus after Dog Bite: A Case Report and Review of the Literature

Primary infection by Capnocytophaga canimorsus after dog bite is rare but may be difficult to identify and rapidly lethal. We describe a case of fatal septic shock with fulminant purpura occurred in a patient without specific risk factor two days after an irrelevant dog bite. The patient was brought to hospital because of altered mental status, fever, and abdominal pain. In a few hours patient became hypoxic and cyanotic. The patient became extremely hypotensive with shock refractory to an aggressive fluid resuscitation (40\u2009ml/kg crystalloids). She received vasoactive drugs, antibiotic therapy, and blood purification treatment, but cardiac arrest unresponsive to resuscitation maneuvers occurred. Case description and literature review demonstrated that, also in patients without specific risk factors, signs of infection after dog bite should be never underestimated and should be treated with a prompt antibiotic therapy initiation even before occurrence of organ dysfunction

Acute renal failure and renal replacement therapy in the postoperative period of orthotopic liver transplant patients versus nonelective abdominal surgery patients

Acute renal failure (ARF) often complicates the postoperative period of patients undergoing orthotopic liver transplantation (OLT); it is habitually associated with high mortality rates. Similarly, patients undergoing major nonelective abdominal surgery are prone to ARF because of their frequent preexistent morbidities, abdominal sepsis, and needed for extended surgical procedures. The aim of this study was to evaluate the incidence of ARF and use of renal replacement therapy (RRT) among OLT versus nonelective abdominal surgery patients and associations with clinical outcomes. We studied all the patients admitted to a surgical intensive care unit (ICU) from January 2008 to December 2009 after OLT or nonelective abdominal surgery. The inclusion criteria were an ICU stay of at least 48 hours and without prior end-stage renal failure. OLT patients (n = 84) were younger and less severly ill than surgery patients (n = 60). ARF occurrence was lower among the OLT (29%) than the surgery group (47%) requiring RRT in 71% and 53% of patients due to ARF, respectively. The ICU mortality of ARF patients in both groups (29% OLT and 51% surgery) were greater than among subjects without ARF (2% and 6%). The occurrence of ARF is common among these two patient groups, and associated with increased risk of death among in surgery (+45%) versus in OLT (+27%) patients. © 2011 Elsevier Inc. All rights reserved

mTOR-Dependent Cell Proliferation in the Brain

The mammalian Target of Rapamycin (mTOR) is a molecular complex equipped with kinase activity which controls cell viability being key in the PI3K/PTEN/Akt pathway. mTOR acts by integrating a number of environmental stimuli to regulate cell growth, proliferation, autophagy, and protein synthesis. These effects are based on the modulation of different metabolic pathways. Upregulation of mTOR associates with various pathological conditions, such as obesity, neurodegeneration, and brain tumors. This is the case of high-grade gliomas with a high propensity to proliferation and tissue invasion. Glioblastoma Multiforme (GBM) is a WHO grade IV malignant, aggressive, and lethal glioma. To date, a few treatments are available although the outcome of GBM patients remains poor. Experimental and pathological findings suggest that mTOR upregulation plays a major role in determining an aggressive phenotype, thus determining relapse and chemoresistance. Among several activities, mTOR-induced autophagy suppression is key in GBM malignancy. In this article, we discuss recent evidence about mTOR signaling and its role in normal brain development and pathological conditions, with a special emphasis on its role in GBM

Methamphetamine persistently increases alpha-synuclein and suppresses gene promoter methylation within striatal neurons

Abstract Methamphetamine (Meth) produces a variety of epigenetic effects in the brain, which are seminal to establish long-lasting alterations in neuronal activity. However, most epigenetic changes were described by measuring the rough amount of either histone acetylation and methylation or direct DNA methylation, without focusing on a specific DNA sequence. This point is key to comprehend Meth-induced phenotypic changes, brain plasticity, addiction and neurodegeneration. In this research paper we analyze the persistence of Meth-induced striatal synucleinopathy at a prolonged time interval of Meth withdrawal. At the same time, Meth-induced alterations, specifically within alpha-synuclein gene (SNCA) or its promoter, were evaluated. We found that exposure to high and/or prolonged doses of Meth, apart from producing nigro-striatal toxicity, determines a long-lasting increase in striatal alpha-synuclein levels. This is consistent along immune-blotting, immune-histochemistry, and electron microscopy. This was neither associated with an increase of SNCA copy number nor with alterations within SNCA sequence. However, we documented persistently demethylation within SNCA promoter, which matches the increase in alpha-synuclein protein. The amount of the native protein, which was measured stoichiometrically within striatal neurons, surpasses the increase reported following SNCA multiplications. Demethylation was remarkable (ten-fold of controls) and steady, even at prolonged time intervals being tested so far (up to 21 days of Meth withdrawal). Similarly alpha-synuclein protein assayed stoichiometrically steadily increased roughly ten-fold of controls. Meth-induced increase of alpha-synuclein was also described within limbic areas. These findings are discussed in the light of Meth-induced epigenetic changes, Meth-induced phenotype alterations, and Meth-induced neurodegeneration

Dysregulated homeostasis of acetylcholine levels in immune cells of RR-multiple sclerosis patients

Multiple sclerosis (MS) is characterized by pro-inflammatory cytokine production. Acetylcholine (ACh) contributes to the modulation of central and peripheral inflammation. We studied the homeostasis of the cholinergic system in relation to cytokine levels in immune cells and sera of relapsing remitting-MS (RR-MS) patients. We demonstrated that lower ACh levels in serum of RR-MS patients were inversely correlated with the increased activity of the hydrolyzing enzymes acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). Interestingly, the expression of the ACh biosynthetic enzyme and the protein carriers involved in non-vesicular ACh release were found overexpressed in peripheral blood mononuclear cells of MS patients. The inflammatory state of the MS patients was confirmed by increased levels of TNF alpha, IL-12/IL-23p40, IL-18. The lower circulating ACh levels in sera of MS patients are dependent on the higher activity of cholinergic hydrolyzing enzymes. The smaller ratio of ACh to TNF alpha, IL-12/IL-23p40 and IL-18 in MS patients, with respect to healthy donors (HD), is indicative of an inflammatory environment probably related to the alteration of cholinergic system homeostasis