Search results for "Biophysics"

Thirty years of synaptosome research.

1993

Detached synapses (synaptosomes), first isolated by the author in 1958 and identified as such in 1960, are sealed presynaptic nerve terminals often with a portion of the target cell--sometimes amounting to a complete dendritic spine--adhering to their external surface. They can be prepared in high yield from brain tissue and also in decreasing yield from spinal cord, retina, sympathetic ganglia, myenteric plexus and electric organs. They are sealed structures which, under metabolizing conditions, respire, take up oxygen and glucose, extrude Na+, accumulate K+, maintain a normal membrane potential and, on depolarization, release transmitter in a Ca(2+)-dependent manner. They thus provide an …

Size influences the effect of hydrophobic nanoparticles on lung surfactant model systems

2013

Item does not contain fulltext The alveolar lung surfactant (LS) is a complex lipid protein mixture that forms an interfacial monolayer reducing the surface tension to near zero values and thus preventing the lungs from collapse. Due to the expanding field of nanotechnology and the corresponding unavoidable exposure of human beings from the air, it is crucial to study the potential effects of nanoparticles (NPs) on the structural organization of the lung surfactant system. In the present study, we investigated both, the domain structure in pure DPPC monolayers as well as in lung surfactant model systems. In the pure lipid system we found that two different sized hydrophobic polymeric nanopa…

In vitro T-cell immunogenicity of oligopeptides derived from the region 92-110 of the 16-kDa protein ofMycobacterium tuberculosis

2004

The 16-kDa protein of Mycobacterium tuberculosis provokes specific immune responses; it is thus a target for the development of peptide-based diagnostic reagents and subunit vaccines. Previous studies have demonstrated the presence of several regions containing murine and human T-cell epitopes. Within the 91–110 immunodominant domain, we found that peptides comprising the sequence of 91SEFAYGSFVRTVSL104 elicit specific T-cell responses in both human T-cell clones and human peripheral blood mononuclear cells (PBMC) from PPD+ (purified protein derivative) individuals. Elongation of this peptide towards the C-terminal end did not provide more effective peptides, but the removal of residue 91Se…

Effect of donor substituents on thermally activated delayed fluorescence of diphenylsulfone derivatives

2019

This research was funded by the European Social Fund according to the activity ‘Improvement of researchers’ qualification by implementing world-class R&D projects’ of Measure No. 09.3.3-LMT-K-712. DG acknowledges to the ERDF PostDoc project No. 1.1.1.2/VIAA/1/16/177;

Promoter and exon–intron structure of the protein kinase C gene from the marine sponge Geodia cydonium: evolutionary considerations and promoter acti…

1999

Abstract We report the gene structure of a key signaling molecule from a marine sponge, Geodia cydonium. The selected gene, which codes for a classical protein kinase C (cPKC), comprises 13 exons and 12 introns; the introns are, in contrast to those found in cPKC from higher Metazoa, small in size ranging from 93 nt to 359 nt. The complete gene has a length of 4229 nt and contains exons which encode the characteristic putative regulatory and catalytic domains of metazoan cPKCs. While in the regulatory domain only one intron is in phase 0, in the catalytic domain most introns are phase 0 introns, suggesting that the latter only rarely undergo module duplication. The 5′-flanking sequence of t…

Toxicological assessment of mesoporous silica particles in the nematode Caenorhabditis elegans

2018

[EN] Here we report the toxicological evaluation of mesoporous silica particles (MSPs) in the nematode C. elegans. Specifically, we have investigated the effect of bare micro- (M0) and nano-sized (N0) MSPs, and their corresponding functionalized particles with a starch derivative (Glu-N) (M1 and N1, respectively) on C. elegans ageing parameters. The toxicity of MSPs, their impact on C. elegans lifespan, movement capacity, progeny and ability to survive upon exposure to acute oxidative stress were assessed. This study demonstrated that both size particles assayed (M0 and N0), labeled with rhodamine and monitored through fluorescence microscopy, are ingested by the nematode. Moreover, toxicit…

Uptake of poly(2-hydroxypropylmethacrylamide)-coated gold nanoparticles in microvascular endothelial cells and transport across the blood-brain barri…

2020

The facile and modular functionalization of gold nanoparticles makes them versatile tools in nanomedicine, for instance, photothermal therapy, contrast agents or as model nanoparticles to probe drug-delivery mechanisms. Since endothelial cells from various locations in the body exhibit unique phenotypes we quantitatively examined the amount of different sized poly(2-hydroxypropylmethacrylamide)-coated gold nanoparticles internalized into primary human dermal endothelial cells or human brain endothelial cells (hCMEC/D3) by inductively coupled plasma atomic emission spectroscopy (ICP-AES) and visualized the nanoparticles using light and electron microscopy. Poly(2-hydroxypropylmethacrylamide)…

Differential mode of inhibition of terminal deoxynucleotidyl transferase by 3′-dATP, ATP, βaraATP and αaraATP

1978

Time, frequency and information domain analysis of short-term heart rate variability before and after focal and generalized seizures in epileptic chi…

2019

OBJECTIVE In this work we explore the potential of combining standard time and frequency domain indexes with novel information measures, to characterize pre- and post-ictal heart rate variability (HRV) in epileptic children, with the aim of differentiating focal and generalized epilepsy regarding the autonomic control mechanisms. APPROACH We analyze short-term HRV in 37 children suffering from generalized or focal epilepsy, monitored 10 s, 300 s, 600 s and 1800 s both before and after seizure episodes. Nine indexes are computed in time (mean, standard deviation of normal-to-normal intervals, root mean square of the successive differences (RMSSD)), frequency (low-to-high frequency power rati…

Fibronectin-bound α5β1 integrins sense load and signal to reinforce adhesion in less than a second

2017

Integrin-mediated mechanosensing of the extracellular environment allows cells to control adhesion and signalling. Whether cells sense and respond to force immediately upon ligand-binding is unknown. Here, we report that during adhesion initiation, fibroblasts respond to mechanical load by strengthening integrin-mediated adhesion to fibronectin (FN) in a biphasic manner. In the first phase, which depends on talin and kindlin as well as on the actin nucleators Arp2/3 and mDia, FN-engaged α5β1 integrins activate focal adhesion kinase (FAK) and c-Src in less than 0.5 s to steeply strengthen α5β1- and αV-class integrin-mediated adhesion. When the mechanical load exceeds a certain threshold, fib…