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result(s) for
"Elsner, Peter"
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Sensitivity and Specificity of Multiphoton Laser Tomography for In Vivo and Ex Vivo Diagnosis of Malignant Melanoma
2009
The incidence of malignant melanoma has shown a dramatic increase over the past three decades. Patient outcome and curability depend on early diagnosis. In vivo multiphoton laser tomography represents a recently developed diagnostic tool that allows non-invasive tissue imaging. We aim to demonstrate the application of multiphoton laser tomography for the in vivo differentiation and diagnosis of melanoma. Laser radiation in the near infrared spectrum was used to image endogenous fluorophores by multiphoton excitation. Eighty-three melanocytic skin lesions have been investigated. The results showed distinct morphological differences in melanoma compared with melanocytic nevi. In particular, six characteristic features of malignant melanoma were specified and statistically evaluated. Sensitivity values up to 95% (range: 71–95%) and specificity values up to 97% (range: 69–97%) were achieved for diagnostic classification. Logistic regression analysis was performed to identify the most significant diagnostic criteria. We found that architectural disarray of the epidermis, poorly defined keratinocyte cell borders as well as the presence of pleomorphic or dendritic cells were of prime importance. By means of this procedure accuracy values up to 97% were reached. These findings underline the potential applicability of multiphoton laser tomography in melanoma diagnosis of melanocytic skin lesions.
Journal Article
Critical physiological factors influencing the outcome of antimicrobial testing according to ISO 22196 / JIS Z 2801
by
Hipler, Uta-Christina
,
Sigusch, Bernd W.
,
Griesheim, Stefanie
in
Antibacterial activity
,
Antibacterial materials
,
Antimicrobial agents
2018
Bactericidal materials gained interest in the health care sector as they are capable of preventing material surfaces from microbial colonization and subsequent spread of infections. However, commercialization of antimicrobial materials requires proof of their efficacy, which is usually done using in vitro methods. The ISO 22196 standard (Japanese test method JIS Z 2801) is a method for measuring the antibacterial activity of daily goods. As it was found reliable for testing the biocidal activity of antimicrobially active materials and surface coatings most of the laboratories participating in this study used this protocol. Therefore, a round robin test for evaluating antimicrobially active biomaterials had to be established. To our knowledge, this is the first report on inaugurating a round robin test for the ISO 22196 / JIS Z 2801. The first round of testing showed that analyses in the different laboratories yielded different results, especially for materials with intermediate antibacterial effects distinctly different efficacies were noted. Scrutinizing the protocols used by the different participants and identifying the factors influencing the test outcomes the approach was unified. Four critical factors influencing the outcome of antibacterial testing were identified in a series of experiments: (1) incubation time, (2) bacteria starting concentration, (3) physiological state of bacteria (stationary or exponential phase of growth), and (4) nutrient concentration. To our knowledge, this is the first time these parameters have been analyzed for their effect on the outcome of testing according to ISO 22196 / JIS Z 2801. In conclusion, to enable assessment of the results obtained it is necessary to evaluate these single parameters in the test protocol carefully. Furthermore, uniform and robust definitions of the terms antibacterial efficacy / activity, bacteriostatic effects, and bactericidal action need to be agreed upon to simplify communication of results and also regulate expectations regarding antimicrobial tests, outcomes, and materials.
Journal Article
pH Influence on Antibacterial Efficacy of Common Antiseptic Substances
by
Hipler, Uta-Christina
,
Ruth, Peter
,
Abel, Martin
in
Anti-Bacterial Agents - pharmacology
,
Anti-Infective Agents, Local - pharmacology
,
Bacterial Load
2015
Background: Wound infection plays an important role in compromised wound healing. A high bioburden impairs healing and leads to formation of a chronic wound. Distinctly higher pH values were observed in chronic wounds compared to acute wounds. However, there is only limited knowledge of pH dependency on the antibacterial efficacy of common antimicrobial substances. Methods: This study investigated the pH influence on the antimicrobial efficacy of povidone (PVP)-iodine, silver nitrate, chlorhexidine, octenidine and polihexanide against Staphylococcus aureus and Pseudomonas aeruginosa using the agar diffusion test and microplate laser nephelometry. Results: The bactericidal activity of chlorhexidine and octenidine was mainly pH-independent in a pH range of 5.0-9.0. In contrast, polihexanide showed a significant efficacy increase at a higher pH. It was also found that the influence of the pH on antiseptics differs among species of bacteria. For instance, S. aureus exhibited an increasing sensitivity against silver nitrate with rising pH whereas the effect on P. aeruginosa was found to be distinctly decreased. The antimicrobial effect of PVP-iodine was strongly diminished with rising pH. Conclusions: The shift towards higher pH values in chronic wounds compared to acute wounds makes it imperative to know whether the antimicrobial efficacy of applied antimicrobial substances is altered by different pH levels. The results suggest that application of polihexanide might be advantageous for the management of wound infections, as both S. aureus and P. aeruginosa exhibited an increased susceptibility with rising pH.
Journal Article
Keratinocyte and Fibroblast Wound Healing In Vitro Is Repressed by Non-Optimal Conditions but the Reparative Potential Can Be Improved by Water-Filtered Infrared A
by
Hipler, Uta-Christina
,
Tittelbach, Jörg
,
Elsner, Peter
in
Cell culture
,
Chronic infection
,
Collagen
2021
It is a general goal to improve wound healing, especially of chronic wounds. As light therapy has gained increasing attention, the positive influence on healing progression of water-filtered infrared A (wIRA), a special form of thermal radiation, has been investigated and compared to the detrimental effects of UV-B irradiation on wound closure in vitro. Models of keratinocyte and fibroblast scratches help to elucidate effects on epithelial and dermal healing. This study further used the simulation of non-optimal settings such as S. aureus infection, chronic inflammation, and anti-inflammatory conditions to determine how these affect scratch wound progression and whether wIRA treatment can improve healing. Gene expression analysis for cytokines (IL1A, IL6, CXCL8), growth (TGFB1, PDGFC) and transcription factors (NFKB1, TP53), heat shock proteins (HSP90AA1, HSPA1A, HSPD1), keratinocyte desmogleins (DSG1, DSG3), and fibroblast collagen (COL1A1, COL3A1) was performed. Keratinocyte and fibroblast wound healing under non-optimal conditions was found to be distinctly reduced in vitro. wIRA treatment could counteract the inflammatory response in infected keratinocytes as well as under chronic inflammatory conditions by decreasing pro-inflammatory cytokine gene expression and improve wound healing. In contrast, in the anti-inflammatory setting, wIRA radiation could re-initiate the acute inflammatory response necessary after injury to stimulate the regenerative processes and advance scratch closure.
Journal Article
In Vitro Lipophilic Antioxidant Capacity, Antidiabetic and Antibacterial Activity of Citrus Fruits Extracts from Aceh, Indonesia
by
Hipler, Uta-Christina
,
Ernawita
,
Wahyuono, Ruri
in
Antibacterial activity
,
Antioxidants
,
Carotenoids
2017
This study reports in vitro lipophilic antioxidant, inhibition of α-amylase and antibacterial activities of extracts of peel and pulp of citrus samples from Aceh, Indonesia. HPLC (high-performance liquid chromatography), phytochemical, and FTIR (fourier transform infrared) analysis detected carotenoids, flavonoids, phenolic acids and terpenoids, contributing to the biological potencies. Most peel and pulp extracts contained lutein and lower concentrations of zeaxanthin, α-carotene, β-carotene and β-cryptoxanthin. The extracts also contained flavanone glycosides (hesperidin, naringin and neohesperidin), flavonol (quercetin) and polymethoxylated flavones (sinensetin, tangeretin). L-TEAC (lipophilic trolox equivalent antioxidant capacity) test determined for peel extracts higher antioxidant capacity compared to pulp extracts. All extracts presented α-amylase inhibitory activity, pulp extracts showing stronger inhibitory activity compared to peel extracts. All extracts inhibited the growth of both gram (+) and gram (−) bacteria, with peel and pulp extracts of makin showing the strongest inhibitory activity. Therefore, local citrus species from Aceh are potential sources of beneficial compounds with possible health preventive effects.
Journal Article
Study of material homogeneity in the long fiber thermoset injection molding process by image texture analysis
by
Liebig, Wilfried V.
,
Maertens, Robert
,
Weidenmann, Kay A.
in
CT analysis
,
Haralick texture feature
,
long glass fiber
2022
To quantify the homogeneity of fiber dispersion in short fiber-reinforced polymer composites, a method for image texture analysis of 3-dimensional X-ray micro computed tomography (µCT) images is presented in this work. The adaption of the method to the specific requirements of the composite material is accomplished using a statistical region merging approach. Subsequently, the method is applied for evaluating the homogeneity of specimens from an intermediate step of the long fiber thermoset injection molding process as well as molded parts. This new injection molding process enables the manufacturing of parts with a flexible combination of short and long glass fibers. By using a newly developed screw element based on the Maddock mixing element design, the material homogeneity of parts molded in the long fiber injection molding process is improved.
Journal Article
Functional and physiological characteristics of the aging skin
by
Farage, Miranda A.
,
Maibach, Howard I.
,
Miller, Kenneth W.
in
Cell Membrane Permeability
,
Geriatrics/Gerontology
,
Humans
2008
As life expectancy in the U.S. increases — and with it the proportion of the aged in the population — appropriate care of elderly skin becomes a medical concern of increasing importance. As skin ages, the intrinsic structural changes that are a natural consequence of passing time are inevitably followed by subsequent physiological changes that affect the skin’s ability to function as the interface between internal and external environments. The pH of the skin surface increases with age, increasing its susceptibility to infection. Neurosensory perception of superficial pain is diminished both in intensity and speed of perception (increasing the risk of thermal injury); deep tissue pain, however, may be enhanced. A decline in lipid content as the skin ages inhibits the permeability of nonlipophilic compounds, reducing the efficacy of some topical medications. Allergic and irritant reactions are blunted, as is the inflammatory response, compromising the ability of the aged skin to affect wound repair. These functional impairments (although a predictable consequence of intrinsic structural changes) have the potential to cause significant morbidity in the elderly patient and may, as well, be greatly exacerbated by extrinsic factors like photodamage. As numbers of the elderly increase, medical as well as cosmetic dermatological interventions will be necessary to optimize the quality of life for this segment of the population.
Journal Article
Cutaneous Manifestations of Diabetes Mellitus: A Review
by
Schliemann, Sibylle
,
Lima, Ana Luiza
,
Elsner, Peter
in
Anaphylaxis
,
Dermatology
,
Dermatomycoses - etiology
2017
Diabetes mellitus is a widespread endocrine disease with severe impact on health systems worldwide. Increased serum glucose causes damage to a wide range of cell types, including endothelial cells, neurons, and renal cells, but also keratinocytes and fibroblasts. Skin disorders can be found in about one third of all people with diabetes and frequently occur before the diagnosis, thus playing an important role in the initial recognition of underlying disease. Noninfectious as well as infectious diseases have been described as dermatologic manifestations of diabetes mellitus. Moreover, diabetic neuropathy and angiopathy may also affect the skin. Pruritus, necrobiosis lipoidica, scleredema adultorum of Buschke, and granuloma annulare are examples of frequent noninfectious skin diseases. Bacterial and fungal skin infections are more frequent in people with diabetes. Diabetic neuropathy and angiopathy are responsible for diabetic foot syndrome and diabetic dermopathy. Furthermore, antidiabetic therapies may provoke dermatologic adverse events. Treatment with insulin may evoke local reactions like lipohypertrophy, lipoatrophy and both instant and delayed type allergy. Erythema multiforme, leukocytoclastic vasculitis, drug eruptions, and photosensitivity have been described as adverse reactions to oral antidiabetics. The identification of lesions may be crucial for the first diagnosis and for proper therapy of diabetes.
Journal Article
Fused filament fabrication: comparison of methods for determining the interfacial strength of single welded tracks
by
Liebig, Wilfried V.
,
Heuer, Anselm
,
Elsner, Peter
in
Additive manufacturing
,
bulk material strength
,
fracture surface
2021
The mechanical properties of plastic-based additively manufactured specimens have been widely discussed. However, there is still no standard that can be used to determine properties such as the interfacial strength of adjacent tracks and also to exclude the influence of varying manufacturing conditions. In this paper, a proposal is made to determine the interfacial strength using specimens with only one track within a layer. For this purpose, so-called single-wall specimens of polylactide were characterised under tensile load and the interfacial area between the adjacent layers was determined using three methods. It turned out that the determination of the interfacial area via the fracture surface is the most accurate method for determining the interfacial strength. The measured interfacial strengths were compared with the bulk material strength and it was found that the bulk material strength can be achieved under optimal conditions in the FFF process. It was also observed that with increasing nozzle temperature, the simultaneous printing of specimens influences the interfacial strength. To conclude, this method allows to measure the interfacial strength without superimposing the influence of voids. However, for example, the interfacial strength within a layer cannot be determined.
Journal Article