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Biomedical subjects

Vedrana Montana

Publications and source records attributed to Vedrana Montana.

6 recordsLinked to original sources
PubMed2006

Vesicular transmitter release from astrocytes.

Astrocytes can release a variety of transmitters, including glutamate and ATP, in response to stimuli that induce increases in intracellular Ca(2+) levels. This release occurs via a regulated, exocytotic pathway. As evidence of this, astrocytes express protein components of the vesicular secretory apparatus, including synaptobrevin 2, syntaxin, and SNAP-23. Additionally, astrocytes possess vesicular organelles, the essential morphological elements required for regulated Ca(2+)-dependent transmitter release. The location of specific exocytotic sites on these cells, however, remains to be unequivocally determined.

Animals↗
PubMed2006

Single molecule mechanical probing of the SNARE protein interactions.

Exocytotic release of neurotransmitters is mediated by the ternary soluble N-ethyl maleimide-sensitive fusion protein attachment protein receptors (SNAREs) complex, comprised of syntaxin (Sx), synaptosome-associated protein of 25 kDa (SNAP25), and synaptobrevin 2 (Sb2). Since exocytosis involves the nonequilibrium process of association and dissociation of bonds between molecules of the SNARE complex, dynamic measurements at the single molecule level are necessary for a detailed understanding of these interactions. To address this issue, we used the atomic force microscope in force spectroscopy mode to show from single molecule investigations of the SNARE complex, that Sx1A and Sb2 are zippered throughout their entire SNARE domains without the involvement of SNAP25. When SNAP25B is present in the complex, it creates a local interaction at the 0 (ionic) layer by cuffing Sx1A and Sb2. Force loading rate studies indicate that the ternary complex interaction is more stable than the Sx1A-Sb2 interaction.

Animals↗
PubMed2005

Chemically functionalized water soluble single-walled carbon nanotubes modulate neurite outgrowth.

We report the use of chemically-functionalized water soluble single-walled carbon nanotube (SWNT) graft copolymers for modulation of outgrowth of neuronal processes. The graft copolymers were prepared by the functionalization of SWNTs with poly-m-aminobenzene sulphonic acid and polyethylene glycol. When added to the culturing medium, these functionalized water soluble SWNTs were able to increase the length of various neuronal processes.

Animals↗
PubMed2004

Vesicular glutamate transporter-dependent glutamate release from astrocytes.

Astrocytes exhibit excitability based on variations of their intracellular Ca2+ concentrations, which leads to glutamate release, that in turn can signal to adjacent neurons. This glutamate-mediated astrocyte-neuron signaling occurs at physiological intracellular Ca2+ levels in astrocytes and includes modulation of synaptic transmission. The mechanism underlying Ca2+-dependent glutamate release from astrocytes is most likely exocytosis, because astrocytes express the protein components of the soluble N-ethyl maleimide-sensitive fusion protein attachment protein receptors complex, including synaptobrevin 2, syntaxin, and synaptosome-associated protein of 23 kDa. Although these proteins mediate Ca2+-dependent glutamate release from astrocytes, it is not well understood whether astrocytes express functional vesicular glutamate transporters (VGLUTs) that are critical for vesicle refilling. Here, we find in cultured and freshly isolated astrocytes the presence of brain-specific Na+-dependent inorganic phosphate cotransporter and differentiation-associated Na+-dependent inorganic phosphate cotransporter that have recently been identified as VGLUTs 1 and 2. Indirect immunocytochemistry showed a punctate pattern of VGLUT immunoreactivity throughout the entire cell body and processes, whereas pharmacological inhibition of VGLUTs abolished mechanically and agonist-evoked Ca2+-dependent glutamate release from astrocytes. Taken together, these data indicate that VGLUTs play a functional role in exocytotic glutamate release from astrocytes.

Amino Acid Transport Systems, Acidic↗
PubMed2003

Botulinum toxin type B micromechanosensor.

Botulinum neurotoxin (BoNT) types A, B, E, and F are toxic to humans; early and rapid detection is essential for adequate medical treatment. Presently available tests for detection of BoNTs, although sensitive, require hours to days. We report a BoNT-B sensor whose properties allow detection of BoNT-B within minutes. The technique relies on the detection of an agarose bead detachment from the tip of a micromachined cantilever resulting from BoNT-B action on its substratum, the synaptic protein synaptobrevin 2, attached to the beads. The mechanical resonance frequency of the cantilever is monitored for the detection. To suspend the bead off the cantilever we use synaptobrevin's molecular interaction with another synaptic protein, syntaxin 1A, that was deposited onto the cantilever tip. Additionally, this bead detachment technique is general and can be used in any displacement reaction, such as in receptor-ligand pairs, where the introduction of one chemical leads to the displacement of another. The technique is of broad interest and will find uses outside toxicology.

Antigens, Surface↗