University of Amsterdam

About: University of Amsterdam is a education organization based out in Amsterdam, Noord-Holland, Netherlands. It is known for research contribution in the topics: Population & Randomized controlled trial. The organization has 59309 authors who have published 140894 publications receiving 5984137 citations. The organization is also known as: UvA & Universiteit van Amsterdam.

Programmed death of T cells in HIV-1 infection

Abstract: In human immunodeficiency virus (HIV) infection, functional defects and deletion of antigen-reactive T cells are more frequent than can be explained by direct viral infection. On culturing, both CD4+ and CD8+ T cells from asymptomatic HIV-infected individuals died as a result of programmed cell death (apoptosis). Apoptosis was enhanced by activation with CD3 antibodies. Programmed cell death, associated with impaired T cell reactivity, may thus be responsible for the deletion of reactive T cells that contributes to HIV-induced immunodeficiency.

Subcortical brain volume abnormalities in 2028 individuals with schizophrenia and 2540 healthy controls via the ENIGMA consortium

Abstract: The profile of brain structural abnormalities in schizophrenia is still not fully understood, despite decades of research using brain scans. To validate a prospective meta-analysis approach to analyzing multicenter neuroimaging data, we analyzed brain MRI scans from 2028 schizophrenia patients and 2540 healthy controls, assessed with standardized methods at 15 centers worldwide. We identified subcortical brain volumes that differentiated patients from controls, and ranked them according to their effect sizes. Compared with healthy controls, patients with schizophrenia had smaller hippocampus (Cohen's d=-0.46), amygdala (d=-0.31), thalamus (d=-0.31), accumbens (d=-0.25) and intracranial volumes (d=-0.12), as well as larger pallidum (d=0.21) and lateral ventricle volumes (d=0.37). Putamen and pallidum volume augmentations were positively associated with duration of illness and hippocampal deficits scaled with the proportion of unmedicated patients. Worldwide cooperative analyses of brain imaging data support a profile of subcortical abnormalities in schizophrenia, which is consistent with that based on traditional meta-analytic approaches. This first ENIGMA Schizophrenia Working Group study validates that collaborative data analyses can readily be used across brain phenotypes and disorders and encourages analysis and data sharing efforts to further our understanding of severe mental illness.

Nutrient excess and the demise of coral reefs and carbonate platforms

Abstract: Growth rates of corals on Holocene reefs indicate that carbonate platforms should easily keep pace with long-term subsidence and sea-level changes, yet drowned reefs and platforms are common in the geologic record. Recognition of the negative influence of nutrients on reef communities provides a clue to that paradox. The primary carbonate-sediment producers of the coral reef community are highly adapted to nutrient-deficient environments. Input of nitrates and phosphates stimulates growth of plankton, which reduces water transparency, limiting depth ranges of zooxanthellate corals and calcareous algae and thereby reducing carbonate production. Higher nutrient concentrations and plankton densities also stimulate growth of fleshy algae and ahermatypic suspension-feeding animals in the benthos. Besides displacing hermatypic algae and corals, many of these fastgrowing competitors are bioeroders that actively destroy thze reefal structure. Because rates of carbonate production and bioerosion are similar, even modest increases in nutrient availability can shift a reef community from net production to net erosion. In the geologic record, drowned reefs and carbonate platforms typically exhibit evidence of nondeposition, bioerosion, and reduced redox potential, which indicate excess nutrient availability during drowning. Drowned reefs overlain by shales are possible victims of nutrients in terrestrial runoff that suppressed reef growth before arrival of siliciclastic sediments. Other drowned platforms may have succumbed during rapid pulses of sea-level rise that flooded previously subaerial platforms. Nutrients in the soils of the flooding platform were mixed into surface waters, suppressing reef growth. The reef drowned if submergence proceeded beyond the critical depth before the excess nutrients were exported from the system. Other mechanisms for reef drowning by excess nutrients include changes in local or regional upwelling patterns or mid-ocean overturn.