Applying two-photon excitation fluorescence lifetime imaging microscopy to study photosynthesis in plant leaves

This study investigates to which extent two-photon excitation (TPE) fluorescence lifetime imaging microscopy can be applied to study picosecond fluorescence kinetics of individual chloroplasts in leaves. Using femtosecond 860 nm excitation pulses, fluorescence lifetimes can be measured in leaves of Arabidopsis thaliana and Alocasia wentii under excitation-annihilation free conditions, both for the F0- and the Fm-state. The corresponding average lifetimes are ~250 ps and ~1.5 ns, respectively, similar to those of isolated chloroplasts. These values appear to be the same for chloroplasts in the top, middle, and bottom layer of the leaves. With the spatial resolution of ~500 nm in the focal (xy) plane and 2 μm in the z direction, it appears to be impossible to fully resolve the grana stacks and stroma lamellae, but variations in the fluorescence lifetimes, and thus of the composition on a pixel-to-pixel base can be observed

A 50% higher prevalence of life-shortening chronic conditions among cancer patients with low socioeconomic status

Background: Comorbidity and socioeconomic status (SES) may be related among cancer patients. Method : Population-based cancer registry study among 72 153 patients diagnosed during 1997-2006. Results : Low SES patients had 50% higher risk of serious comorbidity than those with high SES. Prevalence was increased for each cancer site. Low SES cancer patients had significantly higher risk of also having cardiovascular disease, chronic obstructive pulmonary diseases, diabetes mellitus, cerebrovascular disease, tuberculosis, dementia, and gastrointestinal disease. One-year survival was significantly worse in lowest vs highest SES, partly explained by comorbidity. Conclusion : This illustrates the enormous heterogeneity of cancer patients and stresses the need for optimal treatment of cancer patients with a variety of concomitant chronic conditions

Synapse Pathology in Psychiatric and Neurologic Disease

Inhibitory and excitatory synapses play a fundamental role in information processing in the brain. Excitatory synapses usually are situated on dendritic spines, small membrane protrusions that harbor glutamate receptors and postsynaptic density components and help transmit electrical signals. In recent years, it has become evident that spine morphology is intimately linked to synapse function—smaller spines have smaller synapses and support reduced synaptic transmission. The relationship between synaptic signaling, spine shape, and brain function is never more apparent than when the brain becomes dysfunctional. Many psychiatric and neurologic disorders, ranging from mental retardation and autism to Alzheimer’s disease and addiction, are accompanied by alterations in spine morphology and synapse number. In this review, we highlight the structure and molecular organization of synapses and discuss functional effects of synapse pathology in brain disease

Antigenic Complementarity in the Origins of Autoimmunity: A General Theory Illustrated With a Case Study of Idiopathic Thrombocytopenia Purpura

We describe a novel, testable theory of autoimmunity, outline novel predictions made by the theory, and illustrate its application to unravelling the possible causes of idiopathic thrombocytopenia purpura (ITP). Pairs of stereochemically complementary antigens induce complementary immune responses (antibody or T-cell) that create loss of regulation and civil war within the immune system itself. Antibodies attack antibodies creating circulating immune complexes; T-cells attack T-cells creating perivascular cuffing. This immunological civil war abrogates the self-nonself distinction. If at least one of the complementary antigens mimics a self antigen, then this unregulated immune response will target host tissues as well. Data demonstrating that complementary antigens are found in some animal models of autoimmunity and may be present in various human diseases, especially ITP, are reviewed. Specific mechanisms for preventing autoimmunity or suppressing existing autoimmunity are derived from the theory, and critical tests proposed. Finally, we argue that Koch's postulates are inadequate for establishing disease causation for multiple-antigen diseases and discuss the possibility that current research has failed to elucidate the causes of human autoimmune diseases because we are using the wrong criteria

Determination of Specific Electrocatalytic Sites in the Oxidation of Small Molecules on Crystalline Metal Surfaces

The identification of active sites in electrocatalytic reactions is part of the elucidation of mechanisms of catalyzed reactions on solid surfaces. However, this is not an easy task, even for apparently simple reactions, as we sometimes think the oxidation of adsorbed CO is. For surfaces consisting of non-equivalent sites, the recognition of specific active sites must consider the influence that facets, as is the steps/defect on the surface of the catalyst, cause in its neighbors; one has to consider the electrochemical environment under which the “active sites” lie on the surface, meaning that defects/steps on the surface do not partake in chemistry by themselves. In this paper, we outline the recent efforts in understanding the close relationships between site-specific and the overall rate and/or selectivity of electrocatalytic reactions. We analyze hydrogen adsorption/desorption, and electro-oxidation of CO, methanol, and ammonia. The classical topic of asymmetric electrocatalysis on kinked surfaces is also addressed for glucose electro-oxidation. The article takes into account selected existing data combined with our original works.M.J.S.F. is grateful to PNPD/CAPES (Brazil). J.M.F. thanks the MCINN (FEDER, Spain) project-CTQ-2016-76221-P

Acquired angio-oedema caused by IgA paraprotein

The syndrome of acquired angio-oedema is characterized by late onset of recurrent bouts of angio-oedema or abdominal pain and may be caused by an acquired deficiency of Cl-inhibitor (Cl-INH), the inhibitor of the first component of complement. Acquired Cl-INK deficiency has been described in approximately 50 patients and is strongly associated with malignant B-cell proliferations. We describe a patient with an 8-year history of recurrent abdominal symptoms and angio-oedema with acquired Cl-INH deficiency, caused by the presence of IgA-kappa antibodies that inactivate CI-INH. Analysis of the bone marrow revealed an IgA-kappa monoclonal population of plasma cells, without evidence of overt myeloma. Angio-oedema caused by an autoantibody of the IgA isotype is extremely rare and has never been described in a Dutch patient. Recognition of angio-oedema, both hereditary and acquired, is important because of the therapeutic consequences, as will be discussed. (C) 1998 Elsevier Science B.V