Hohenstein Institutes

Germany

Hohenstein Institutes

Germany
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Hoefer D.,Hohenstein Institutes | Schnepf J.K.,Hohenstein Institutes | Hammer T.R.,Hohenstein Institutes | Fischer M.,University of Ulm | Marquardt C.,Regionale Kliniken Holding RKH GmbH
Journal of Materials Science: Materials in Medicine | Year: 2015

Marine alginate fibre dressings are well established in wound management. Alginate fibres can absorb plenty of wound exudate due to their gel forming abilities and ion exchange. Alginates from bacteria have never been studied for medical applications so far, although the microbial polymer raises expectations for improved gelling capacity due to its unique O-acetylation. To prove the gelling capacity of bacterial alginate, we extracted the co-polymer from fermentation of the soil bacterium Azotobacter vinelandii ATCC 9046, cultivated on crude glycerol as an alternative carbon source. Bacterial alginate was isolated in high purity and extruded by a wet spinning method. Fibre structure and properties were characterised by infrared spectroscopy, NMR, GPC, scanning electron microscopy and tensile testing. The fibres could be processed into biocompatible needle web dressings, which showed more than twice the gel formation in saline compared to commercial dressings made of marine alginates. Gelled dressings of bacterial alginate formed stable hydrogels of sufficient shape and strength for wound healing applications. This work suggests that the increased gel formation of bacterial alginate from A. vinelandii may be optimal for the preparation of novel wound dressings. © 2015, Springer Science+Business Media New York.


Hammer T.R.,Hohenstein Institutes | Mucha H.,Hohenstein Institutes | Hoefer D.,Hohenstein Institutes
Mycopathologia | Year: 2011

In the developed countries infections of the feet (tinea pedis, athlete's foot) and nails (onychomycosis) with the anthropophile fungus Trichophyton rubrum are most common. We examined the propagation of dermatophytes before and during domestic laundering. About 10% of the infectious material was transferred from contaminated textiles to sterile textiles during storage in a clothes basket simulation indicating a high infection risk during storage. This was evaluated with two quantification techniques: cultivation with subsequent colony counting and tracing of radioactively labelled propagating units. Both approaches reliably revealed similar results with the latter method reducing experimental time to few minutes compared to 2 weeks with the traditional method. The tracer technique allowed favourably to directly reflect the textile-bound infectious material at the moment of skin contact. To address the infection risk during domestic laundry, bioindicators with T. rubrum or the yeast Candida albicans were introduced into common domestic washing procedures with different temperature courses. While C. albicans did not survive any of the tests, T. rubrum could be recovered after washing at 30°C, indicating the risk potential of dermatophyte infections at home. Up to 16% of the initial fungus load was detected in the rinsing water. Washing at 60°C however, eliminated both pathogens, T. rubrum and C. albicans. © 2010 Springer Science+Business Media B.V.


Handel M.,Hohenstein Institutes | Hammer T.R.,Hohenstein Institutes | Hoefer D.,Hohenstein Institutes
Biomedical Materials (Bristol) | Year: 2012

Adipose tissue engineering, instead of tissue substitution, often uses autologous adipose tissue-derived stem cells (hASC). These cells are known to improve graft integration and to support neovascularization of scaffolds when seeded onto biomaterials. In this study we thought to engineer adipose tissue using scaffold-bound hASC, since they can be differentiated into the adipocyte cell lineage and used for soft tissue regeneration. We show here by microscopy and gene expression of the peroxysome proliferator-activated receptor gene (PPARγ2) that hASC growing on polypropylene fibrous scaffolds as well as on three-dimensional nonwoven scaffolds can be turned into adipose tissue within 19 days. Freshly isolated hASC displayed a higher differentiation potential than hASC cultured for eight passages. In addition, we proved a modified alginate microcapsule to directly induce adipogenic differentiation of incorporated hASC. The results may help to improve long-term success of adipose tissue regeneration, especially for large-scale soft tissue defects, and support the development of cell-scaffold combinations which can be shaped individually and directly induce the adipogenic differentiation of incorporated hASC at the site of implantation. © 2012 IOP Publishing Ltd.


Gerhardts A.,Hohenstein Institutes | Hammer T.R.,Hohenstein Institutes | Balluff C.,Hohenstein Institutes | Mucha H.,Hohenstein Institutes | Hoefer D.,Hohenstein Institutes
Journal of Applied Microbiology | Year: 2012

Aim: Gastro-intestinal infections are widespread in the community and have considerable economic consequences. In this study, we followed chains of infection from a public toilet scenario, looking at infection risks by correlating the transmission of bacteria, fungi and viruses to our current knowledge of infectious doses. Methods and Results: Transmission of Escherichia coli, Bacillus atrophaeus spores, Candida albicans and bacteriophage MS2 from hands to surfaces was examined in a transmission model, that is toilet brush, door handle to water tap. The load of viable pathogens was significantly reduced during transfer from hands to objects. Nevertheless, it was shown that pathogens were successfully transferred to other people in contagious doses by contact with contaminated surfaces. Conclusions: Our results suggest that infection risks are mainly dependent on current infectious doses of pathogens. For enteritic viruses or bacteria, for example Norovirus or EHEC, only a few particles or cells are sufficient for infection in public lavatories, thus bearing a high risk of infection for other persons. However, there seems to be only a low probability of becoming infected with pathogens that have a high infectious dose whilst sharing the same bathroom. Significance and Impact of the Study: The transmission model for micro-organisms enables a risk assessment of gastro-intestinal infections on the basis of a practical approach. © 2012 The Authors. Journal of Applied Microbiology © 2012 The Society for Applied Microbiology.


Hammer T.R.,Hohenstein Institutes | Fischer K.,Hohenstein Institutes | Mueller M.,Hohenstein Institutes | Hoefer D.,Hohenstein Institutes
International Journal of Hygiene and Environmental Health | Year: 2011

Toxic substances from cigarette smoke can attach to carpets, curtains, clothes or other surfaces and thus may pose risks to affected persons. The phenomenon itself and the potential hazards are discussed controversially, but scientific data are rare. The objective of this study was to examine the potential of textile-bound nicotine for permeation through human skin and to assess the effects of cigarette smoke extracts from clothes on fibroblasts, neurocytes and zebrafish embryos. Tritiated nicotine from contaminated cotton textiles penetrated through adult human full-thickness skin as well as through a 3D in vitro skin model in diffusion chambers. We also observed a significant concentration-dependent cytotoxicity of textile smoke extracts on fibroblast viability and structure as well as on neurocytes. Early larval tests with zebrafish embryos were used as a valid assay for testing acute vertebrate toxicity. Zebrafish development was delayed and most of the embryos died when exposed to smoke extracts from textiles. Our data show that textiles contaminated with cigarette smoke represent a potential source of nicotine uptake and can provoke adverse health effects. © 2011 Elsevier GmbH.


Handel M.,Hohenstein Institutes | Hammer T.R.,Hohenstein Institutes | Nooeaid P.,Friedrich - Alexander - University, Erlangen - Nuremberg | Boccaccini A.R.,Friedrich - Alexander - University, Erlangen - Nuremberg | Hoefer D.,Hohenstein Institutes
Tissue Engineering - Part A | Year: 2013

Poor vascularization is the key limitation for long-term acceptance of large three-dimensional (3D) tissue engineering constructs in regenerative medicine. 45S5 Bioglass® was investigated given its potential for applications in bone engineering. Since native Bioglass® shows insufficient angiogenic properties, we used a collagen coating, to seed human adipose tissue-derived stem cells (hASC) confluently onto 3D 45S5 Bioglass ®-based scaffolds. To investigate vascularization by semiquantitative analyses, these biofunctionalized scaffolds were then subjected to in vitro human umbilical vein endothelial cells formation assays, and were also investigated in the chorioallantoic membrane (CAM) angiogenesis model, an in vivo angiogenesis assay, which uses the CAM of the hen's egg. In their native, nonbiofunctionalized state, neither Bioglass®-based nor biologically inert fibrous polypropylene control scaffolds showed angiogenic properties. However, significant vascularization was induced by hASC-seeded scaffolds (Bioglass® and polypropylene) in the CAM angiogenesis assay. Biofunctionalized scaffolds also showed enhanced tube lengths, compared to unmodified scaffolds or constructs seeded with fibroblasts. In case of biologically inert hernia meshes, the quantification of vascular endothelial growth factor secretion as the key angiogenic stimulus strongly correlated to the tube lengths and vessel numbers in all models. This correlation proved the CAM angiogenesis assay to be a suitable semiquantitative tool to characterize angiogenic effects of larger 3D implants. In addition, our results suggest that combinations of suitable scaffold materials, such as 45S5 Bioglass ®, with hASC could be a promising approach for future tissue engineering applications. © 2013 Mary Ann Liebert, Inc.


Hoefer D.,Hohenstein Institutes | Handel M.,Hohenstein Institutes | Muller K.-M.,Neuromarketing Labs | Hammer T.R.,Hohenstein Institutes
Skin Research and Technology | Year: 2016

Background/purpose: Neurophysiologic data on reactions of the human brain towards tactile stimuli evoked by fabrics moved on the skin are scarce. Furthermore, evaluation of fabrics' pleasantness using questionnaires suffers subjective biases. That is why we used a 64-channel electroencephalography (EEG) to objectively evaluate real-time brain reactions to fabric–skin interactions. Methods: Tactile stimuli were triggered by selected fabrics of different qualities, i.e. modal/polyamide single jersey, cotton double rib and a jute fabric, applied hidden to either the palm or forearm of 24 subjects via a custom-made fabric-to-skin applicator called SOFIA. One-way anova analysis was carried out to verify the EEG data. Results: The modal/polyamide fabric applied to the forearm and palm led to slightly stronger emotional valence scores in the brain than the conventional or baseline fabric. Furthermore, the single jersey elicits significant higher event-related potential (ERP) signals in all subjects when applied to the forearm, suggesting less distraction and better cognitive resources during the fabric/skin interaction. The brain thus reacts with instantaneous ERP to tactile stimulation of fabrics and is able to discriminate different qualities via implicit preferences. Conclusion: The test procedure described here may be a tool to evaluate the fabric feel with the exclusion of subjective biases. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd


PubMed | Hohenstein Institutes
Type: Comparative Study | Journal: Journal of materials science. Materials in medicine | Year: 2015

Marine alginate fibre dressings are well established in wound management. Alginate fibres can absorb plenty of wound exudate due to their gel forming abilities and ion exchange. Alginates from bacteria have never been studied for medical applications so far, although the microbial polymer raises expectations for improved gelling capacity due to its unique O-acetylation. To prove the gelling capacity of bacterial alginate, we extracted the co-polymer from fermentation of the soil bacterium Azotobacter vinelandii ATCC 9046, cultivated on crude glycerol as an alternative carbon source. Bacterial alginate was isolated in high purity and extruded by a wet spinning method. Fibre structure and properties were characterised by infrared spectroscopy, NMR, GPC, scanning electron microscopy and tensile testing. The fibres could be processed into biocompatible needle web dressings, which showed more than twice the gel formation in saline compared to commercial dressings made of marine alginates. Gelled dressings of bacterial alginate formed stable hydrogels of sufficient shape and strength for wound healing applications. This work suggests that the increased gel formation of bacterial alginate from A. vinelandii may be optimal for the preparation of novel wound dressings.


PubMed | Hohenstein Institutes
Type: Journal Article | Journal: Tissue engineering. Part A | Year: 2013

Poor vascularization is the key limitation for long-term acceptance of large three-dimensional (3D) tissue engineering constructs in regenerative medicine. 45S5 Bioglass() was investigated given its potential for applications in bone engineering. Since native Bioglass() shows insufficient angiogenic properties, we used a collagen coating, to seed human adipose tissue-derived stem cells (hASC) confluently onto 3D 45S5 Bioglass()-based scaffolds. To investigate vascularization by semiquantitative analyses, these biofunctionalized scaffolds were then subjected to in vitro human umbilical vein endothelial cells formation assays, and were also investigated in the chorioallantoic membrane (CAM) angiogenesis model, an in vivo angiogenesis assay, which uses the CAM of the hens egg. In their native, nonbiofunctionalized state, neither Bioglass()-based nor biologically inert fibrous polypropylene control scaffolds showed angiogenic properties. However, significant vascularization was induced by hASC-seeded scaffolds (Bioglass() and polypropylene) in the CAM angiogenesis assay. Biofunctionalized scaffolds also showed enhanced tube lengths, compared to unmodified scaffolds or constructs seeded with fibroblasts. In case of biologically inert hernia meshes, the quantification of vascular endothelial growth factor secretion as the key angiogenic stimulus strongly correlated to the tube lengths and vessel numbers in all models. This correlation proved the CAM angiogenesis assay to be a suitable semiquantitative tool to characterize angiogenic effects of larger 3D implants. In addition, our results suggest that combinations of suitable scaffold materials, such as 45S5 Bioglass(), with hASC could be a promising approach for future tissue engineering applications.


PubMed | Neuromarketing Labs and Hohenstein Institutes
Type: Journal Article | Journal: Skin research and technology : official journal of International Society for Bioengineering and the Skin (ISBS) [and] International Society for Digital Imaging of Skin (ISDIS) [and] International Society for Skin Imaging (ISSI) | Year: 2016

Neurophysiologic data on reactions of the human brain towards tactile stimuli evoked by fabrics moved on the skin are scarce. Furthermore, evaluation of fabrics pleasantness using questionnaires suffers subjective biases. That is why we used a 64-channel electroencephalography (EEG) to objectively evaluate real-time brain reactions to fabric-skin interactions.Tactile stimuli were triggered by selected fabrics of different qualities, i.e. modal/polyamide single jersey, cotton double rib and a jute fabric, applied hidden to either the palm or forearm of 24 subjects via a custom-made fabric-to-skin applicator called SOFIA. One-way anova analysis was carried out to verify the EEG data.The modal/polyamide fabric applied to the forearm and palm led to slightly stronger emotional valence scores in the brain than the conventional or baseline fabric. Furthermore, the single jersey elicits significant higher event-related potential (ERP) signals in all subjects when applied to the forearm, suggesting less distraction and better cognitive resources during the fabric/skin interaction. The brain thus reacts with instantaneous ERP to tactile stimulation of fabrics and is able to discriminate different qualities via implicit preferences.The test procedure described here may be a tool to evaluate the fabric feel with the exclusion of subjective biases.

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