Development of a tanning technology with Tanning agents from Ligustrum vulgare

Content: The use of vegetable tanning agents alone for pre-tanning as an alternative to synthetic or chromiumcontaining tanning agents is one way of improving sustainability and ecology in leather production. In recent years, a new group of secondary plant compounds, the iridoids or secoiridoids, has been discovered for use as tanning agents. Due to their molecular structure, these substances probably have a reaction mechanism similar to glutaraldehyde, which means that known disadvantages of conventional vegetable tanning such as long process times or weak interactions can be avoided. Currently, a tanning agent from olive leaves with cross-linking active substances deriving from the secoiridoid Oleuropein is commercially available. In order to extend the product range of alternative vegetable tanning agents with covalent cross-linking mechanism by native raw material, we screened a number of further plants for such crosslinking active substances in a preceding project. Extracts from privet leaves showed a particularly high crosslinking activity. Privet belongs to the Oleacea family and is common in Asia with several species. In Europe, the species Ligustrum vulgare can be found everywhere, especially as a hedge plant. In addition to Oleuropein, the privet extracts contain a high proportion of the secoiridoid Ligustraloside A. The secoiridoids are deglycosylated during extraction and thus converted into an activated state. The analytical determination of the active secoiridoid degradation products is not yet possible, so that the quantitative determination of the tannin content is made more difficult. Here, we aimed to develop a technology for the production of leather that is exclusively pre- tanned with privet tanning agents. The development includes the production, characterization and optimization of the plant extracts, the development of the pre-tanning technology and the adaptation of the wet end for the corresponding application areas. The leathers which have been manufactured show high shrinkage temperature and good mechanical properties. They show an inherent coloring, but seem to be suitable for use in automotive interiors, as a comparison of the test results with the technical delivery conditions of automobile manufacturers shows. Take-Away: With a new tanning agent from a native widespread plant, leather of good quality can be produced

Charakterisierung der Rezeptoreigenschaften ausgewählter Clathratbildner für die Detektion flüchtiger organischer Verbindungen in einem thermochemischen Sensor

In der Arbeit wurde erstmals die Eignung von Silizium-Bauelementen mit monolithisch integrierten Thermosäulen als Wärmeleistungstransducer für thermochemische Sensoren zur Detektion flüchtiger organischer Verbindungen (VOC) untersucht. Dabei wurden bereits in massensensitiven und kapazitiven Sensoren bewährte Polymerschichten als chemisch sensitive Rezeptoren verwendet. Als Kriterien für die Bewertung des Sensors dienten Empfindlichkeit, Signal-Rausch-Verhältnis, Reproduzierbarkeit und Signaldynamik. Weiterhin konnte die für die Anwendung der Silizium-Thermosäulen entwickelte Methodik zur Charakterisierung neuer organischer Clathratbildner als potentielle Rezeptormaterialien genutzt werden. Für die untersuchten Clathratbildner wurden die Empfindlichkeiten und die Signaldynamik gegenüber einer Auswahl typischer organischer Lösungsmittel gemessen. Es konnte festgestellt werden, dass die Empfindlichkeitsrelationen deutlich von den Eigenschaften der Rezeptorschichten bestimmt werden und damit eine Mustererkennung in entsprechend konfigurierten Sensorarrays möglich sein sollte. Entgegen den Erwartungen spielt jedoch für die Selektivität der Rezeptorschichten der stereoselektive Effekt der Clathratbildung keine Rolle, da entsprechende Phasenumwandlungen erst oberhalb sensorrelevanter Partialdrücke auftreten und der Messeffekt lediglich durch Adsorption erzeugt wird

Factors influencing study engagement during the COVID-19 pandemic: A cross-sectional study among health and social professions students

Background: The aim of this study is to explore factors influencing the study engagement of health and social professions students during the COVID-19 pandemic. While antecedents of study engagement have been studied previously, the factors influencing engagement under pandemic conditions have not yet been investigated. Furthermore, there is a particular need for research among students in health and social professions programs, as these students are particularly affected by the pandemic. As theoretical basis, the study draws on the demands-resources-theory. It is hypothesized that pandemic-related study and personal resources drive engagement during the pandemic, and that pandemic-related demands negatively influence engagement. Method: The study uses a cross-sectional survey to explore the hypothesized effects. The sample consists of 559 university students of health and social professions in Germany. The study was carried out in July 2020, towards the end of the first digital semester and after the first peak in COVID-19 cases. Data are analyzed using linear multiple regression analysis. Results: The findings show that the demands-resources-theory is suitable to explain study engagement even under pandemic conditions. Suitable digital learning formats and social support are identified as important study resources for study engagement during major life events, while emotional resilience, active self-care and academic self-efficacy are identified as important personal resources. Conclusions: Under pandemic conditions academic institutions should focus on providing beneficial teaching formats and innovative ways to support students lacking social networks. Besides, they should consider developing means to help students structuring daily life as well as establishing initiatives to strengthen students' self-efficacy beliefs

Psychological Stress among Students in Health-Related Fields during the COVID-19 Pandemic: Results of a Cross-Sectional Study at Selected Munich Universities

The COVID-19 pandemic has been a challenging period of upheaval for higher education students. This study aims to assess the factors associated with psychological stress during the COVID-19 pandemic among a sample of students in health-related fields at Munich universities in Germany. Students (n = 623) from KSH Munich and LMU Munich completed an online cross-sectional survey. Information on demographics and academic and everyday difficulties due to the COVID-19 pandemic as well as data on physical and mental health were collected. Multivariable logistic regression analyses were performed to identify factors associated with the outcome. The prevalence for higher psychological stress was 44% among the study population. Factors associated with higher psychological stress were: lower overall life satisfaction (p < 0.0001), worsened health situation (p < 0.0001), lack of social support (p = 0.0301) and social interaction (p = 0.0115), worries about financial difficulties due to loss of income (p = 0.0134), stressful thoughts about a second wave (p < 0.0001), feeling unable to positively influence the situation (p = 0.0262) and study-related effects, such as perceived study burden (p = 0.0003) and likely delay in studies (p = 0.0178)). The COVID-19 pandemic is having a significant negative impact on the mental health of students in health-related fields. Proactive efforts to support the mental health and well-being of students are needed

Expression pattern of matrix metalloproteinases in human gynecological cancer cell lines

Background: Matrix metalloproteinases (MMPs) are involved in the degradation of protein components of the extracellular matrix and thus play an important role in tumor invasion and metastasis. Their expression is related to the progression of gynecological cancers (e.g. endometrial, cervical or ovarian carcinoma). In this study we investigated the expression pattern of the 23 MMPs, currently known in humans, in different gynecological cancer cell lines. Methods: In total, cell lines from three endometrium carcinomas (Ishikawa, HEC-1-A, AN3 CA), three cervical carcinomas (HeLa, Caski, SiHa), three chorioncarcinomas (JEG, JAR, BeWo), two ovarian cancers (BG-1, OAW-42) and one teratocarcinoma (PA-1) were examined. The expression of MMPs was analyzed by RT-PCR, Western blot and gelatin zymography. Results: We demonstrated that the cell lines examined can constitutively express a wide variety of MMPs on mRNA and protein level. While MMP-2, -11, -14 and -24 were widely expressed, no expression was seen for MMP-12, -16, -20, -25, -26, -27 in any of the cell lines. A broad range of 16 MMPs could be found in the PA1 cells and thus this cell line could be used as a positive control for general MMP experiments. While the three cervical cancer cell lines expressed 10-14 different MMPs, the median expression in endometrial and choriocarcinoma cells was 7 different enzymes. The two investigated ovarian cancer cell lines showed a distinctive difference in the number of expressed MMPs (2 vs. 10). Conclusions: Ishikawa, Caski, OAW-42 and BeWo cell lines could be the best choice for all future experiments on MMP regulation and their role in endometrial, cervical, ovarian or choriocarcinoma development, whereas the teratocarcinoma cell line PA1 could be used as a positive control for general MMP experiments

Viscoelastic Behavior of Embroidered Scaffolds for ACL Tissue Engineering Made of PLA and P(LA-CL) After In Vitro Degradation

A rupture of the anterior cruciate ligament (ACL) is the most common knee ligament injury. Current applied reconstruction methods have limitations in terms of graft availability and mechanical properties. A new approach could be the use of a tissue engineering construct that temporarily reflects the mechanical properties of native ligament tissues and acts as a carrier structure for cell seeding. In this study, embroidered scaffolds composed of polylactic acid (PLA) and poly(lactic-co-"-caprolactone) (P(LA-CL)) threads were tested mechanically for their viscoelastic behavior under in vitro degradation. The relaxation behavior of both scaffold types (moco: mono-component scaffold made of PLA threads, bico: bi-component scaffold made of PLA and P(LA-CL) threads) was comparable to native lapine ACL. Most of the lapine ACL cells survived 32 days of cell culture and grew along the fibers. Cell vitality was comparable for moco and bico scaffolds. Lapine ACL cells were able to adhere to the polymer surfaces and spread along the threads throughout the scaffold. The mechanical behavior of degrading matrices with and without cells showed no significant differences. These results demonstrate the potential of embroidered scaffolds as an ACL tissue engineering approach. © 2019 by the authors. Licensee MDPI, Basel, Switzerland

Cruciate Ligament Cell Sheets Can Be Rapidly Produced on Thermoresponsive poly(glycidyl ether) Coating and Successfully Used for Colonization of Embroidered Scaffolds

Anterior cruciate ligament (ACL) cell sheets combined with biomechanically competent scaffolds might facilitate ACL tissue engineering. Since thermoresponsive polymers allow a rapid enzyme-free detachment of cell sheets, we evaluated the applicability of a thermoresponsive poly(glycidyl ether) (PGE) coating for cruciate ligamentocyte sheet formation and its influence on ligamentocyte phenotype during sheet-mediated colonization of embroidered scaffolds. Ligamentocytes were seeded on surfaces either coated with PGE or without coating. Detached ligamentocyte sheets were cultured separately or wrapped around an embroidered scaffold made of polylactide acid (PLA) and poly(lactic-co-ε-caprolactone) (P(LA-CL)) threads functionalized by gas-phase fluorination and with collagen foam. Ligamentocyte viability, protein and gene expression were determined in sheets detached from surfaces with or without PGE coating, scaffolds seeded with sheets from PGE-coated plates and the respective monolayers. Stable and vital ligamentocyte sheets could be produced within 24 h with both surfaces, but more rapidly with PGE coating. PGE did not affect ligamentocyte phenotype. Scaffolds could be colonized with sheets associated with high cell survival, stable gene expression of ligament-related type I collagen, decorin, tenascin C and Mohawk after 14 d and extracellular matrix (ECM) deposition. PGE coating facilitates ligamentocyte sheet formation, and sheets colonizing the scaffolds displayed a ligament-related phenotype

In vivo ligamentogenesis in embroidered poly(lactic-co-ε-caprolactone) / polylactic acid scaffolds functionalized by fluorination and hexamethylene diisocyanate cross-linked collagen foams

Although autografts represent the gold standard for anterior cruciate ligament (ACL) reconstruction, tissue-engineered ACLs provide a prospect to minimize donor site morbidity and limited graft availability. This study characterizes the ligamentogenesis in embroidered poly(L-lactide-co-epsilon-caprolactone) (P(LA-CL)) / polylactic acid (PLA) constructs using a dynamic nude mice xenograft model. (P(LA-CL))/PLA scaffolds remained either untreated (co) or were functionalized by gas fluorination (F), collagen foam cross-linked with hexamethylene diisocyanate (HMDI) (coll), or F combined with the foam (F+coll). Cell-free constructs or those seeded for 1 week with lapine ACL ligamentocytes were implanted into nude mice for 12 weeks. Following explantation, cell vitality and content, histo(patho)logy of scaffolds (including organs: liver, kidney, spleen), sulphated glycosaminoglycan (sGAG) contents and biomechanical properties were assessed. Scaffolds did not affect mice weight development and organs, indicating no organ toxicity. Moreover, scaffolds maintained their size and shape and reflected a high cell viability prior to and following implantation. Coll or F+coll scaffolds seeded with cells yielded superior macroscopic properties compared to the controls. Mild signs of inflammation (foreign-body giant cells and hyperemia) were limited to scaffolds without collagen. Microscopical score values and sGAG content did not differ significantly. Although remaining stable after explantation, elastic modulus, maximum force, tensile strength and strain at F-max were significantly lower in explanted scaffolds compared to those before implantation, with no significant differences between scaffold subtypes, except for a higher maximum force in F+coll compared with F samples (in vivo). Scaffold functionalization with fluorinated collagen foam provides a promising approach for ACL tissue engineering

Charakterisierung der Rezeptoreigenschaften ausgewählter Clathratbildner für die Detektion flüchtiger organischer Verbindungen in einem thermochemischen Sensor

In der Arbeit wurde erstmals die Eignung von Silizium-Bauelementen mit monolithisch integrierten Thermosäulen als Wärmeleistungstransducer für thermochemische Sensoren zur Detektion flüchtiger organischer Verbindungen (VOC) untersucht. Dabei wurden bereits in massensensitiven und kapazitiven Sensoren bewährte Polymerschichten als chemisch sensitive Rezeptoren verwendet. Als Kriterien für die Bewertung des Sensors dienten Empfindlichkeit, Signal-Rausch-Verhältnis, Reproduzierbarkeit und Signaldynamik. Weiterhin konnte die für die Anwendung der Silizium-Thermosäulen entwickelte Methodik zur Charakterisierung neuer organischer Clathratbildner als potentielle Rezeptormaterialien genutzt werden. Für die untersuchten Clathratbildner wurden die Empfindlichkeiten und die Signaldynamik gegenüber einer Auswahl typischer organischer Lösungsmittel gemessen. Es konnte festgestellt werden, dass die Empfindlichkeitsrelationen deutlich von den Eigenschaften der Rezeptorschichten bestimmt werden und damit eine Mustererkennung in entsprechend konfigurierten Sensorarrays möglich sein sollte. Entgegen den Erwartungen spielt jedoch für die Selektivität der Rezeptorschichten der stereoselektive Effekt der Clathratbildung keine Rolle, da entsprechende Phasenumwandlungen erst oberhalb sensorrelevanter Partialdrücke auftreten und der Messeffekt lediglich durch Adsorption erzeugt wird

Charakterisierung der Rezeptoreigenschaften ausgewählter Clathratbildner für die Detektion flüchtiger organischer Verbindungen in einem thermochemischen Sensor

In der Arbeit wurde erstmals die Eignung von Silizium-Bauelementen mit monolithisch integrierten Thermosäulen als Wärmeleistungstransducer für thermochemische Sensoren zur Detektion flüchtiger organischer Verbindungen (VOC) untersucht. Dabei wurden bereits in massensensitiven und kapazitiven Sensoren bewährte Polymerschichten als chemisch sensitive Rezeptoren verwendet. Als Kriterien für die Bewertung des Sensors dienten Empfindlichkeit, Signal-Rausch-Verhältnis, Reproduzierbarkeit und Signaldynamik. Weiterhin konnte die für die Anwendung der Silizium-Thermosäulen entwickelte Methodik zur Charakterisierung neuer organischer Clathratbildner als potentielle Rezeptormaterialien genutzt werden. Für die untersuchten Clathratbildner wurden die Empfindlichkeiten und die Signaldynamik gegenüber einer Auswahl typischer organischer Lösungsmittel gemessen. Es konnte festgestellt werden, dass die Empfindlichkeitsrelationen deutlich von den Eigenschaften der Rezeptorschichten bestimmt werden und damit eine Mustererkennung in entsprechend konfigurierten Sensorarrays möglich sein sollte. Entgegen den Erwartungen spielt jedoch für die Selektivität der Rezeptorschichten der stereoselektive Effekt der Clathratbildung keine Rolle, da entsprechende Phasenumwandlungen erst oberhalb sensorrelevanter Partialdrücke auftreten und der Messeffekt lediglich durch Adsorption erzeugt wird