H. Stachelberger

Bio: H. Stachelberger is an academic researcher from Vienna University of Technology. The author has contributed to research in topics: Substantia nigra & Biomimetics. The author has an hindex of 12, co-authored 29 publications receiving 924 citations.

Iron-Melanin Complex in Substantia Nigra of Parkinsonian Brains: An X-Ray Microanalysis

Abstract: Using energy-dispersive x-ray analysis on an electron microscope working in the scanning transmission electron microscopy mode equipped with a microanalysis system, we studied the subcellular distribution of trace elements in neuromelanin-containing neurons of the substantia nigra zona compacta (SNZC) of three cases of idiopathic Parkinson's disease (PD) [one with Alzheimer's disease (AD)] and of three controls, in Lewy bodies of SNZC, and in synthetic dopamine-melanin chemically charged or uncharged with Fe Weak but significant Fe peaks similar to those of a synthetic melanin-Fe3+ complex were seen only in intraneuronal highly electron-dense neuromelanin granules of SNZC cells of PD brains, with the highest levels in a case of PD plus AD whereas a synthetic melanin-Fe2+ complex showed much lower iron peaks, indicating that neuromelanin has higher affinity for Fe3+ than for Fe2+ No detectable Fe was seen in nonmelanized cytoplasm of SNZC neurons and in the adjacent neuropil in both PD and controls, in Lewy bodies in SNZC neurons in PD, and in synthetic dopamine-melanin uncharged with iron These findings, demonstrating for the first time a neuromelanin-iron complex in dopaminergic SNZC neurons in PD, support the assumption that an iron-melanin interaction contributes significantly to dopaminergic neurodegeneration in PD and PD plus AD

Atomic force microscopy study of living diatoms in ambient conditions

Abstract: Summary We present the first in vivo study of diatoms using atomic force microscopy (AFM). Three chain-forming, benthic freshwater species ‐ Eunotia sudetica, Navicula seminulum and a yet unidentified species ‐ are directly imaged while growing on glass slides. Using the AFM, we imaged the topography of the diatom frustules at the nanometre range scale and we determined the thickness of the organic case enveloping the siliceous skeleton of the cell (10 nm). Imaging proved to be stable for several hours, thereby offering the possibility to study long-term dynamic changes, such as biomineralization or cell movement, as they occur. We also focused on the natural adhesives produced by these unicellular organisms to adhere to other cells or the substratum. Most man-made adhesives fail in wet conditions, owing to chemical modification of the adhesive or its substrate. Diatoms produce adhesives that are extremely strong and robust both in fresh- and in seawater environments. Our phase-imaging and force-pulling experiments reveal the characteristics of these natural adhesives that might be of use in designing man-made analogues that function in wet environments. Engineering stable underwater adhesives currently poses a major technical challenge.

Diatom bionanotribology--biological surfaces in relative motion: their design, friction, adhesion, lubrication and wear.

Abstract: Tribology is the branch of engineering that deals with the interaction of surfaces in relative motion (as in bearings or gears): their design, friction, adhesion, lubrication and wear. Continuous miniaturization of technological devices like hard disc drives and biosensors increases the necessity for the fundamental understanding of tribological phenomena at the micro- and nanoscale. Biological systems show optimized performance also at this scale. Examples for biological friction systems at different length scales include bacterial flagella, joints, articular cartilage and muscle connective tissues. Scanning probe microscopy opened the nanocosmos to engineers: not only is microscopy now possible on the atomic scale, but even manipulation of single atoms and molecules can be performed with unprecedented precision. As opposed to this top-down approach, biological systems excel in bottom-up nanotechnology. Our model system for bionanotribological investigations are diatoms, for they are small, highly reproductive, and since they are transparent, they are accessible with different kinds of optical microscopy methods. Furthermore, certain diatoms have proved to be rewarding samples for mechanical and topological in vivo investigations on the nanoscale. There are several diatom species that actively move (e.g. Bacillaria paxillifer forms colonies in which the single cells slide against each other) or which can, as cell colonies, be elongated by as much as a major fraction of their original length (e.g. Ellerbeckia arenaria colonies can be reversibly elongated by one third of their original length). Therefore, we assume that some sort of lubrication of interactive surfaces is present in these species. Current studies in diatom bionanotribology comprise techniques like atomic force microscopy, histochemical analysis, infrared spectrometry, molecular spectroscopy and confocal infrared microscopy.

Metals in Neurobiology: Probing Their Chemistry and Biology with Molecular Imaging

Abstract: The brain is a singular organ of unique biological complexity that serves as the command center for cognitive and motor function. As such, this specialized system also possesses a unique chemical composition and reactivity at the molecular level. In this regard, two vital distinguishing features of the brain are its requirements for the highest concentrations of metal ions in the body and the highest per-weight consumption of body oxygen. In humans, the brain accounts for only 2% of total body mass but consumes 20% of the oxygen that is taken in through respiration. As a consequence of high oxygen demand and cell complexity, distinctly high metal levels pervade all regions of the brain and central nervous system. Structural roles for metal ions in the brain and the body include the stabilization of biomolecules in static (e.g., Mg2+ for nucleic acid folds, Zn2+ in zinc-finger transcription factors) or dynamic (e.g., Na+ and K+ in ion channels, Ca2+ in neuronal cell signaling) modes, and catalytic roles for brain metal ions are also numerous and often of special demand.

Oxidative stress in neurodegeneration: cause or consequence?

Abstract: Oxidative stress has long been linked to the neuronal cell death that is associated with certain neurodegenerative conditions. Whether it is a primary cause or merely a downstream consequence of the neurodegenerative process is still an open question, however. The advent of a growing number of in vitro and in vivo models that emulate human disease pathology is aiding scientists in deciphering just where oxidative stress intersects with other cellular events in the emerging roadmap leading to neurodegeneration. Here I review the evidence for oxidative stress in neurodegeneration and how this relates to other cellular events.

Iron, brain ageing and neurodegenerative disorders

Abstract: There is increasing evidence that iron is involved in the mechanisms that underlie many neurodegenerative diseases. Conditions such as neuroferritinopathy and Friedreich ataxia are associated with mutations in genes that encode proteins that are involved in iron metabolism, and as the brain ages, iron accumulates in regions that are affected by Alzheimer's disease and Parkinson's disease. High concentrations of reactive iron can increase oxidative-stress induced neuronal vulnerability, and iron accumulation might increase the toxicity of environmental or endogenous toxins. By studying the accumulation and cellular distribution of iron during ageing, we should be able to increase our understanding of these neurodegenerative disorders and develop new therapeutic strategies.