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Biomedical subjects

M Scholl

Publications and source records attributed to M Scholl.

10 recordsLinked to original sources
PubMed2001

Aligned microcontact printing of biomolecules on microelectronic device surfaces.

Microcontact printing (muCP) of extracellular matrix proteins is a fascinating approach to control cell positioning and outgrowth, which is essential in the development of applications ranging from cellular biosensors to tissue engineering. Microelectronic devices can be used to detect the activity from a large number of recording sites over the long term. However, signals from cells can only be recorded at small sensitive spots. In this paper, we present an innovative setup to perform aligned muCP of extracellular matrix proteins on microelectronic devices in order to guide the growth of electrogenic cells specifically to these sensitive spots. Our system is based on the combination of a fine-placer with redesigned micro stamps having a rigid glass cylinder as backbone for attachment in the alignment tool. Alignment is performed moving the device with an optical table under microscopic control of the superimposed images from stamp and device surface. After successful alignment, the stamp is brought into contact with the device surface by means of a high-precision lever. With our setup, we were able to pattern up to 40 devices per hour. A lateral alignment accuracy of < 2microm has been achieved. Aligned neuronal growth on patterned devices was demonstrated with dissociated hippocampal neurons.

Animals↗
PubMed2000

Ordered networks of rat hippocampal neurons attached to silicon oxide surfaces.

The control of neuronal cell position and outgrowth is of fundamental interest in the development of applications ranging from cellular biosensors to tissue engineering. We have produced rectangular networks of functional rat hippocampal neurons on silicon oxide surfaces. Attachment and network formation of neurons was guided by a geometrical grid pattern of the adhesion peptide PA22-2 which matches in sequence a part of the A-chain of laminin. PA22-2 was applied by contact printing onto the functionalised silicon oxide surface and was immobilised by hetero-bifunctional cross-linking with sulfo-GMBS. Geometric pattern matching was achieved by microcontact printing using a polydimethylsiloxane (PDMS) stamp. In this way the produced grid pattern ranged from 3 to 20 microm in line width and from 50 to 100 microm in line distances. As shown by atomic force microscopy (AFM), line widths and line distances of the peptide pattern differ less than 0.5 microm from the used PDMS stamp. The height of the layer of immobilised PA22-2 was approximately 3.5 nm implying the layer to be monomolecular. Immobilised PA22-2 was capable of binding anti-PA22-2 antibodies indicating that the function of the peptide was not compromised by immobilisation. Rat hippocampal neurons, cultured at low density in serum-free medium, were applied to the growth matrix of PA22-2-coated substrates and, within 1-3 h of culture, formed a network-like pattern that more or less matched the printed grid. Reliability and reproducibility of neuronal network formation depended on the geometry, line width and node diameter of the grid pattern. The immobilised neurons showed resting membrane potentials comparable with controls and, already after 1 day of culture, were capable of eliciting action potentials. The suitability of the immobilised neurons for the study of man-made neural networks and for multi-site recordings from a functional neuronal network is discussed.

Animals↗
PubMed1999

Synthesis and activity of a new generation of ruthenium-based olefin metathesis catalysts coordinated with 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene ligands.

[formula: see text] A new family of 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene-substituted ruthenium-based complexes 9a-c has been prepared starting from RuCl2(=CHPh)(PCy3)2 2. These air- and water-tolerant complexes were shown to exhibit an increased ring-closing metathesis activity at elevated temperature when compared to that of the parent complex 2 and the previously developed complex 3. In many instances the activity of these complexes also rivaled or exceeded that of the alkoxy-imido molybdenum complex 1. Catalyst loadings of as low as 0.05 mol% could be used.

Alkenes↗
PubMed1999

Bioassay development: the implications of cardiac myocyte motility in vitro.

Cardiac myocytes cultured over microfabricated extracellular recording devices can be used to assay bioactive compounds. However, electrophysiological signals recorded from these devices vary in amplitude with time. Theoretically, changes in signal amplitude arise from myocytes being moved over recording sites by cocultured fibroblasts. To test this, neonatal rat cardiac myocytes were cultured at high densities and low densities on fibronectin-coated glass. After 36.5 h, myocytes were identified by their rhythmic contractions and then time-lapse-recorded for 3.5 h. Length, width, and angle of orientation was then determined every 30 min for five cells in low density and five cells in high-density culture. Low-density cells had mean lengths of 65.3 microm and widths of 35.1 microm, whereas cells in high-density culture had greater mean lengths of 74.2 microm and lower mean widths of 24.3 microm. Length, width, and angle of orientation of cells in low- and high-density culture changed by 4.1%, 11.8%, and 2.7 degrees, and 6.4%, 10%, and 4.6 degrees, respectively, every half hour. We found no evidence of myocyte-fibroblast interactions influencing cell position or shape in low density, but in high density, we found evidence that fibroblast-myocyte interactions could transiently influence cell shape. We conclude that fibroblast-independent changes in cell shape are largely responsible for the changes in signal amplitude recorded from cardiac myocytes cultured on microfabricated extracellular recording devices. However, there is some evidence that myocyte-fibroblast interactions may augment this process in high-density culture. The implications of these findings for bioassay development are discussed.

Animals↗
PubMed1999

Neuronal networks in vitro: formation and organization on biofunctionalized surfaces.

Receptor-mediated recognition of substrate molecules is a prerequisite for nerve cells in order to find their target structures in vivo and leads to formation of neuronal connections and networks. In order to study these mechanisms under in vitro conditions, we cultured embryonic hippocampal neurons or neuronal cell lines, SH-SY5Y and PCC7-PCC7-Mz1, onto biofunctionalized surfaces. Micropatterning on polymer surfaces, glass- and silicone-oxide-based chip materials was performed in a micrometer range by microcontact printing using polydimethylsiloxane (PDMS) stamps. Hippocampal neurons were found to form networks on chip surfaces under serum-free conditions and remained functional for more than a week. Human neuroblastoma cells SH-SY5Y as well as PCC7-Mz1 stem cells were found to follow microcontact printed pattern on polystyrene surfaces. Both cell lines showed neuronal marker expression and were cultured for up to 7 days with serum containing culture medium. Widths of 3-5 microm of coating lines were found to enhance single cell spreading along the pattern. The techniques described in this study may be useful in promoting nerve cell regeneration and organization following transection due to trauma or surgery. The neuronal alignment and network formation in vitro may furthermore serve as a model system in the field of biosensors.

Journal Article↗
PubMed1993

[Quality of life and coping in the comparison of various groups of chronic illness during inpatient rehabilitation].

The concept of adaptation and quality of life has gained central importance in the research on chronically ill patients and their rehabilitation. This contribution examines the impact of psychological and behavioural factors on the quality of life and coping processes in two groups of chronically ill patients (i.e., n = 48 myocardial infarction survivors, and n = 48 patients with liver diseases). Coping responses and quality of life were measured using Janke et al.'s stress coping questionnaire SVF (1985), while other variables (psychosocial stress and social support) were determined by a variety of self-report data, test measures (von Zerssen's emotional state scale, 1976), as well as interview data, with repeat data compilation after three years (longitudinal study). Significant differences were found for each of the patient groups. Effectiveness of coping appeared to be negatively linked with frequent use of "avoidance", "denial", and "resignation" in patients with psychosocial strain and lack of information. The choice of coping strategy seems to be multi-determined and is related to illness state and sex, with changes occurring over time. The knowledge of coping strategy preferences is highly relevant for the relationship between physician and patient as well as for the process of rehabilitation.

Adaptation, Psychological↗
PubMed1991

[Coping processes in selected groups of chronically ill patients].

The concept of coping has gained a central importance in research on chronic disease. Underlying methodological aspects are briefly reviewed. This study examined the psychological and behavioral correlates of major coping strategies used by medically ill patients in dealing with their illness (N = 48 patients with myocardial infarction and 48 patients with liver-complaints) during the rehabilitation. Coping response was measured by the "Stressverarbeitungsfragebogen" by Janke et al. (1985), while other variables (psycho-social factors) were tapped by a variety of self-report, test measures (Zerssen-Scale-1976-for emotional state) as well as by interview data in a time of three years (longitudinal study). Significant differences were found for each of the patient-groups. Effectiveness of coping appeared to be negatively linked to frequent use of "avoidance" and "resignation" in patients with psycho-social strain. The choice of a specific coping strategy is most likely multidetermined and depends of the connection with illness-state and is changed over time. The knowledge of coping strategy preferences has a very important function for the relationship between physician and patient and process of rehabilitation.

Adaptation, Psychological↗
PubMed1984

Lithium and lecithin treatment in Alzheimer's disease: a pilot study.

Ten patients with presumed Alzheimer's disease were entered into a pilot study to evaluate the combined effects of lithium and lecithin on cognitive and behavioral parameters. The loss of patients from the study because of toxic effects of lithium was high (30%), and one patient was dropped because of an intervening illness. Of the six remaining patients who completed the study, only two showed behavioral improvement; none showed improvement on measures of cognitive functioning. The possible mechanisms of action are discussed.

Aged↗