Terminal Differentiation of Human Fibroblasts is Induced by Radiation

In order to analyze the effect of various kinds of radiation on the terminal differentiation processes of fibroblasts in culture, both human skin and lung fibroblasts were irradiated with electromagnetic non ionizing as well as ionizing radiation in clonal and sparse mass culture systems. As analyzed by cell biological (cell type frequencies), biochemical (collagen synthesis) and molecular markers (expression of protein PIVa) human skin and lung fibroblasts are induced to differentiate prematurely into terminal postmitotic cells. Thus, both electromagnetic and ionizing radiation induce terminal differentiation in cultured cells. These data add some new aspects for the interpretation of radiation effects on cells, e.g., in clinical therapy, as well as for the development of normal tissue responses during early and late effects after radiotherapy

In vivo evolution of tumour cells after the generation of double-strand DNA breaks

In vitro, the ratio of single- to double-strand DNA breaks (DSB) and their absolute values determine the cell death pathway. The consequences of the generation of various numbers of DSB generated in vivo in tumour cells have been analysed in two different experimental tumour models. Synchronisation of DSB generation and control of their number have been achieved using different doses of bleomycin (BLM) and tumour cell permeabilisation by means of locally delivered electric pulses. According to BLM dose, different cell death pathways are observed. At a low therapeutic dose, a mitotic cell death pathway is detected. It is characterised by the appearance of 'atypical mitosis', TUNEL and caspase-3 positive, 24 h after the treatment, and later by the presence of typical apoptotic figures, mainly TUNEL positive but caspase-3 negative. Caspase-3 is thus an early marker of apoptosis. Mitotic cell death is also followed by lymphocytic infiltration reaction. At high doses of BLM, pseudoapoptosis is detected within a few minutes after the treatment. These cell death pathways are discussed as a function of the number of DSB generated, by comparison with previous results obtained in vitro using BLM or ionising radiation

Multi-tier Loyalty Programs to Stimulate Customer Engagement

Customers differ in their purchase behavior, profitability, attitude toward the firm, and so on. These differences between customers have led to numerous firms introducing multi-tier loyalty programs. A multi-tier loyalty program explicitly distinguishes between customers by means of hierarchical tiers (e.g. Silver, Gold, Platinum) and assigns customers to different tiers based on their past purchase behavior. Next, customers in different tiers are provided varying levels of tangible rewards and intangible benefits, which are potentially powerful instruments to stimulate customer engagement. In this chapter, we focus on the design and effectiveness of such multi-tier loyalty programs. Building on loyalty program and customer prioritization research, we discuss whether, why, and how multi-tier loyalty programs are effective (or not) in influencing customer behavior, thereby enhancing customer engagement and financial performance

Consumer–brand identification revisited: An integrative framework of brand identification, customer satisfaction, and price image and their role for brand loyalty and word of mouth

Consumer–brand identification has received considerable attraction among scholars and practitioners in recent years. We contribute to previous research by proposing an integrative model that includes consumer–brand identification, customer satisfaction, and price image to investigate the interrelationships among these constructs as well as their effects on brand loyalty and positive word of mouth. To provide general results, we empirically test the model using a sample of 1443 respondents from a representative consumer panel and 10 service/product brands. The results demonstrate that identification, satisfaction, and price image significantly influence both loyalty and word of mouth. Moreover, we find significant interrelationships among the constructs: Identification positively influences both satisfaction and price image, which also increases satisfaction. By disclosing the relative importance of three separate ways of gaining and retaining customers, this study helps managers more appropriately choose the right mix of branding, pricing, and relationship marketing. From an academic point of view, our research is the first to explicitly examine the effects of the concept of identification for price management and to integrate variables from the fields of branding, relationship marketing, and behavioral pricing, which have separately been identified as particularly important determinants of marketing outcomes

Evolution of Cooperation in Social Dilemmas: Signaling Internalized Norms

Economists have a long tradition in identifying the evolution of cooperation in large, unstructured societies as a puzzle. We suggest a new explanation for cooperation which avoids restrictions of most previous attempts. Our explanation deals with the role of internalized norms for cooperation in large unstructured populations. Even internalized norms, i.e. norms which alter the perceived utility from acting in a cooperative or in an uncooperative way, will not help to overcome a dilemma in an unstructured society, unless and this is the thrust of the current paper individuals are able to signal their property of being a norm bearer. Only when internalization of the norm may be communicated in a reliable way, the picture may change. We derive necessary and sufficient condition for cooperation to be part of an evolutionary stable equilibrium. These conditions relate signaling cost of norm-adopters and non-adopters, the strength of the social norm and parameter measuring the cost of cooperation

Elektronenmikroskopische Untersuchungen über die Entwicklung normaler und röntgenbestrahlter Zellen des Weizenembryos

The normal development of mesophyll cells of germinating wheat embryos was investigated and compared with the development of embryos which had been irradiated with high X-ray doses (200-800 kR). Air dry irradiated seeds were capable of germination and developed into small plantlets of up to 19 mm in length. Nuclei in various mitotic stages were rarely found in the embryonic tissues. Their existence can be explained by the occurrence of prophasic nuclei which were found occasionally in the resting embryos. Lipoiddroplets were distinguishable from spherosomes and from round or elliptic and strongly osmiophilic bodies. During germination the resorption of reserve materials (lipoid bodies and round or elliptic bodies) proceeds normally in the irradiated tissues. No obviousalteration has been found during the development of the endoplasmatic reticulum, the central vacuole and the chloroplasts. After the irradiation ofpregerminated seeds a significant decrease in diameter of mitochondria has been determined and an increase in fixationinstability seems to occur. The embryos, which had been irradiated in the dry state, do not reveal such conspicuous disturbances comparable to those found in zoological objects after X-irradiation, despite the high X-ray doses. The cells developed normally and thespeed of this development is approximately the same as that of the cells of the controls. Between 12 and 21 days after soaking the irradiated seeds on moist filter paper, the plantlets die even under sterile conditions