Psammoma body: A product of dystrophic calcification or of a biologically active process that aims at limiting the growth and spread of tumor?

Dilip K. Das

doi:10.1002/dc.21081

Dissecting neural pathways for forgetting in Drosophila olfactory aversive memory

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1512792112 ◽

2015 ◽

Vol 112 (48) ◽

pp. E6663-E6672 ◽

Cited By ~ 31

Author(s):

Yichun Shuai ◽

Areekul Hirokawa ◽

Yulian Ai ◽

Min Zhang ◽

Wanhe Li ◽

...

Keyword(s):

Reversal Learning ◽

Dopaminergic Neurons ◽

Mushroom Body ◽

Biologically Active ◽

Molecular Pathways ◽

Neural Pathways ◽

Active Process ◽

Glutamatergic Neurons ◽

Memory Decay ◽

Over Time

Recent studies have identified molecular pathways driving forgetting and supported the notion that forgetting is a biologically active process. The circuit mechanisms of forgetting, however, remain largely unknown. Here we report two sets of Drosophila neurons that account for the rapid forgetting of early olfactory aversive memory. We show that inactivating these neurons inhibits memory decay without altering learning, whereas activating them promotes forgetting. These neurons, including a cluster of dopaminergic neurons (PAM-β′1) and a pair of glutamatergic neurons (MBON-γ4>γ1γ2), terminate in distinct subdomains in the mushroom body and represent parallel neural pathways for regulating forgetting. Interestingly, although activity of these neurons is required for memory decay over time, they are not required for acute forgetting during reversal learning. Our results thus not only establish the presence of multiple neural pathways for forgetting in Drosophila but also suggest the existence of diverse circuit mechanisms of forgetting in different contexts.

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Ultrastructural study of the formation of psammoma bodies in fibroblastic meningioma

Journal of Neurosurgery ◽

10.3171/jns.1984.60.3.0512 ◽

1984 ◽

Vol 60 (3) ◽

pp. 512-517 ◽

Cited By ~ 24

Author(s):

Toshihiko Kubota ◽

Kazufumi Sato ◽

Shinjiro Yamamoto ◽

Asao Hirano

Keyword(s):

Matrix Vesicles ◽

Dystrophic Calcification ◽

Psammoma Body ◽

Psammoma Bodies ◽

Content Type ◽

Large Numbers ◽

Cell Processes ◽

Membrane Bound ◽

Fibroblastic Meningioma ◽

Hydroxyapatite Crystals

✓ The fine structure of psammoma bodies was examined in four cases of fibroblastic meningioma. In general, large numbers of various-sized calcified bodies (psammoma bodies) were scattered among the interstitial fibers. In these bodies, the smallest calcific site was found in the extracellular membrane-bound matrix vesicles, which measured approximately 0.1 to 0.2 µ in diameter. In addition, extracellular “matrix giant bodies,” with or without hydroxyapatite aggregates and measuring up to 3 µ in diameter, were frequently encountered. These bodies were apparently invested with single, double, or multiple concentric walls averaging nearly 0.1 µ thick. They presumably originated from the neoplastic cells as a consequence of cytoplasmic residuals associated with cellular degeneration or necrotic cell processes. Hydroxyapatite crystals precipitated repeatedly within the bodies. The precipitate may gradually aggregate within the bodies, and gather in clusters, resulting in a large psammoma body. Finally, collagen fibers around the calcified giant bodies accrued deposits of apatite crystals to make a huge psammoma body. These findings suggest that both matrix giant bodies and matrix vesicles may serve as initial nidus of calcification of psammoma bodies in fibroblastic meningioma. Consequently, this mineralization process may represent a certain dystrophic calcification of meningocytic cells.

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Characterization of photosystem II with the atomic-force microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100130365 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1146-1147

Author(s):

Kathleen M. Marr ◽

Mary K. Lyon

Keyword(s):

Photosystem Ii ◽

Atomic Force Microscope ◽

Three Dimensional ◽

Biologically Active ◽

Atomic Force ◽

Freeze Etching ◽

Image Averaging ◽

Oxygen Evolving ◽

Averaging Techniques

Photosystem II (PSII) is different from all other reaction centers in that it splits water to evolve oxygen and hydrogen ions. This unique ability to evolve oxygen is partly due to three oxygen evolving polypeptides (OEPs) associated with the PSII complex. Freeze etching on grana derived insideout membranes revealed that the OEPs contribute to the observed tetrameric nature of the PSIl particle; when the OEPs are removed, a distinct dimer emerges. Thus, the surface of the PSII complex changes dramatically upon removal of these polypeptides. The atomic force microscope (AFM) is ideal for examining surface topography. The instrument provides a topographical view of individual PSII complexes, giving relatively high resolution three-dimensional information without image averaging techniques. In addition, the use of a fluid cell allows a biologically active sample to be maintained under fully hydrated and physiologically buffered conditions. The OEPs associated with PSII may be sequentially removed, thereby changing the surface of the complex by one polypeptide at a time.

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Depletion and Reconstitution of Active E. Coli Ribosomes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100116826 ◽

1975 ◽

Vol 33 ◽

pp. 640-641

Author(s):

M. Boublik ◽

W. Hellmann ◽

F. Jenkins

Keyword(s):

Protein Biosynthesis ◽

Large Subunit ◽

High Resolution Electron Microscopy ◽

Small Subunit ◽

Structure And Function ◽

Biologically Active ◽

Biological Macromolecules ◽

E Coli ◽

Resolution Electron ◽

And Function

Correlations between structure and function of biological macromolecules have been studied intensively for many years, mostly by indirect methods. High resolution electron microscopy is a unique tool which can provide such information directly by comparing the conformation of biopolymers in their biologically active and inactive state. We have correlated the structure and function of ribosomes, ribonucleoprotein particles which are the site of protein biosynthesis. 70S E. coli ribosomes, used in this experiment, are composed of two subunits - large (50S) and small (30S). The large subunit consists of 34 proteins and two different ribonucleic acid molecules. The small subunit contains 21 proteins and one RNA molecule. All proteins (with the exception of L7 and L12) are present in one copy per ribosome.This study deals with the changes in the fine structure of E. coli ribosomes depleted of proteins L7 and L12. These proteins are unique in many aspects.

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Fractionation of the Biologically Active Large Molecular Components of Human Gastric Content

Gastroenterology ◽

10.1016/s0016-5085(19)35388-0 ◽

1959 ◽

Vol 37 (4) ◽

pp. 439-444 ◽

Cited By ~ 1

Author(s):

Ranwel Caputto ◽

William O. Smith ◽

Jordan Tang ◽

Raul E. Trucco ◽

Walter Joel ◽

...

Keyword(s):

Gastric Content ◽

Biologically Active ◽

Molecular Components

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Bioavailability of naringenin chalcone in humans after ingestion of cherry tomatoes

International Journal for Vitamin and Nutrition Research ◽

10.1024/0300-9831/a000574 ◽

2020 ◽

Vol 90 (5-6) ◽

pp. 411-416 ◽

Cited By ~ 2

Author(s):

Carina Kolot ◽

Ana Rodriguez-Mateos ◽

Rodrigo Feliciano ◽

Katharina Bottermann ◽

Wilhelm Stahl

Keyword(s):

Plasma Levels ◽

Average Concentration ◽

Biologically Active ◽

Thiol Groups ◽

Structural Element ◽

Active Molecule ◽

Reactive Center ◽

Average Maximum ◽

Alpha Beta ◽

Cherry Tomatoes

Abstract. Chalcones are a type of flavonoids characterized by an α-β unsaturated structural element which may react with thiol groups to activate pathways such as the Nrf2-Keap-1 system. Naringenin chalcone is abundant in the diet but little is known about its bioavailability. In this work, the bioavailability of naringenin chalcone from tomatoes was investigated in a group of healthy men (n=10). After ingestion of 600 grams of tomatoes providing a single dose of 17.3 mg naringenin chalcone, 0.2 mg of naringenin, and 195 mg naringin plasma levels of free and conjugated naringenin and naringenin chalcone (glucuronide and sulfate) were analyzed by UHPLC-QTOF-MS at 0.5, 1, 3, and 6 h post-consumption. Plasma levels of conjugated naringenin increased to about 12 nmol/L with a maximum at about 3 h. Concentrations of free naringenin hardly elevated above baseline. Plasma levels of free and conjugated naringenin chalcone significantly increased. A maximum of the conjugated chalcone was reached at about 3 h after ingestion with an average concentration of about 0.5 nmol/L. No free chalcone was detectable at baseline but low amounts of the unconjugated compound could be detected with an average maximum of 0.8 nmol/L at about 1 h after ingestion. The data demonstrate that naringenin chalcone is bioavailable in humans from cherry tomatoes as a dietary source. However, availability is poor and intramolecular cyclisation as well as extended metabolism likely contribute to the inactivation of the reactive alpha-beta unsaturated reactive center as well as the excretion of the biologically active molecule, respectively.

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