1,721,053 research outputs found
ER-mitochondria tethering and Ca2+ crosstalk: The IP3R team takes the field
No full textInter-organelle communication represents a booming topic in cell biology research, with endoplasmic reticulum (ER)-mitochondria coupling playing the lion's share. In a recent work, Bartok and colleagues found that inositol trisphosphates receptors (IP3Rs), in addition to their well-known involvement in ER-mitochondria Ca2+ transfer, are endowed with structural properties at organelles' interface
Key Signalling Molecules in Aging and Neurodegeneration
Full text link: One of the major challenges of modern medicine is to block or prevent the neurodegenerative processes inevitably associated with different pathological conditions [...]
Injection Technologies and Mixture Formation Strategies for SI and Dual-fuel Engines
No full textFuel injection systems and performance is fundamental to combustion engine performance in terms of power, noise, efficiency, and exhaust emissions. There is a move toward electric vehicles (EVs) to reduce carbon emissions, but this is unlikely to be a rapid transition, in part due to EV batteries: their size, cost, longevity, and charging capabilities as well as the scarcity of materials to produce them. Until these issues are resolved, refining the spark-ignited engine is necessary address both sustainability and demand for affordable and reliable mobility. Even under policies oriented to smart sustainable mobility, spark-ignited engines remain strategic, because they can be applied to hybridized EVs or can be fueled with gasoline blended with bioethanol or bio-butanol to drastically reduce particulate matter emissions of direct injection engines in addition to lower CO2 emissions.
In this book, Alessandro Ferrari and Pietro Pizzo provide a full review of spark-ignited engine fuel injection systems. The most popular typologies of fuel injection systems are considered, with special focus on state-of-the-art solutions. Dedicated sections on the methods for air mass evaluation, fuel delivery low-pressure modules, and the specific subsystems for idle, cold start, and warm-up control are also included. The authors pay special attention to mixture formation strategies, as they are a fundamental theme for SI engines. An exhaustive overview of fuel injection technologies is provided, and mixture formation strategies for spark ignited combustion engines are considered. Fuel Injection Systems illustrates the performance of these systems and will also serve as a reference for engineers who are active in the aftermarket, offering detailed information on fuel injection system solutions that are mounted in older vehicles
The complex web of membrane contact sites in brain aging and neurodegeneration
Full text linkTo sustain the essential biological functions required for life, eukaryotic cells rely on complex interactions between different intracellular compartments. Membrane contact sites (MCS), regions where organelles come into close proximity, have recently emerged as major hubs for cellular communication, mediating a broad range of physiological processes, including calcium signalling, lipid synthesis and bioenergetics. MCS are particularly abundant and indispensable in polarized and long-lived cells, such as neurons, where they support both structural and functional integrity. In this review, we explore the functional diversity, molecular composition, and dynamic regulation of key mammalian MCS: endoplasmic reticulum (ER)-plasma membrane, ER-mitochondria and contact sites involving lipid droplets. We highlight their central role in neuronal health and discuss how MCS dysfunction has increasingly been recognized as a hallmark of brain aging and various neurodegenerative diseases, most notably Alzheimer's disease, where altered MCS dynamics contribute to pathogenesis. Finally, we emphasize the therapeutic potential of targeting MCS and outline key unanswered questions to guide future research
Chelation of cytoplasmic Ca2+ increases plasma membrane permeability in murine macrophages
No full textCytoplasmic free Ca2+ (Ca2+i) was chelated to 10-20 nM in the macrophage cell line J774 either by incubation with quin2 acetoxymethyl ester in the absence of external Ca2+ (Di Virgilio, F., Lew, P.D., and Pozzan, T. (1984) Nature 310, 691-693) or by loading [ethyl-enebis(oxyethylenenitrilo)]tetraacetic acid (EGTA) into the cytoplasm via reversible permeabilization of the plasma membrane with extracellular ATP (Steinberg, T.H., Newman, A.S., Swanson, J.A., and Silverstein, SS.C. (1987) J. Biol. Chem. 262, 8884-8888; Di Virgilio, F., Meyer, B.C., Greenberg, S., and Silverstein, S.C. (1988) J. Cell Biol. 106, 657-666). After removal of ATP from the incubation medium, ATP-permeabilized Ca2+i-depleted macrophages recovered a near-normal plasma membrane potential which slowly depolarized over a 2-4 h incubation at low [Ca2+]i. In both ATP-treated and quin2-loaded cells, depolarization of plasma membrane potential was paralleled by an increase in plasma membrane permeability to low molecular weight aqueous solutes such as eosin yellowish (Mr 692), ethidium bromide (Mr 394), and lucifer yellow (Mr 463). This increased plasma membrane permeability was not accompanied by release of the cytoplasmic marker lactic dehydrogenase for incubations up to 4 h and was likely a specific effect of Ca2+i depletion since it was not caused by: (i) the mere incubation of macrophages with extracellular EGTA, i.e. at near-normal [Ca2+]i; and (ii) loading into the cytoplasm of diethylenetriaminepentaacetic acid, a specific chelator of heavy metals with low affinity for Ca2+. Treatment of Ca2+i-depleted cells with direct (phorbol 12-myristate 13-acetate) or indirect (platelet-activating factor) activators of protein kinase C prevented the increase in plasma membrane permeability. Down-regulation of protein kinase C rendered Ca2+i-depleted macrophages refractory to the protective effect of phorbol 12-myristate 13-acetate. This report suggests a role for Ca2+i and possibly protein kinase C in the regulation of plasma membrane permeability to low molecular weight aqueous solutes
Better to keep in touch: investigating inter-organelle cross-talk
No full textThe strategic importance for cellular organelles of being in contact with each other, exchanging messenger molecules, is nowadays well established. Different inter-organelle cross-talk pathways finely regulate multiple physiological cellular mechanisms, and their dysregulation has been found to underlie different pathological conditions. In the last years, a great effort has been made to study such organelle interactions, to understand their functional roles within the cell and the molecules involved in their formation and/or modulation. In this contribution, some examples of organelle cross-talk and their contributions in regulating physiological processes are presented. Moreover, the pro and cons of the available methods for a proper, reliable investigation of membrane contact sites are described
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
- …
