Macroporous Scaffolds for Bone Engineering. Studies on Cell Culture and Ectopic Bone Formation

Bone engineering is a rapidly developing area of reconstructive medicine where bone inducing factors and/or cells are combined with a scaffold material to regenerate the structure and function of the original tissue. The aim of this study was to compare the suitability of different macroporous scaffold types for bone engineering applications. The two scaffold categories studied were a) the mechanically strong and stable titanium fiber meshes and b) the elastic and biodegradable porous polymers. Furthermore, bioactive modifications were applied to these basic scaffold types, and their effect on the osteogenic responses was evaluated in cell culture and ectopic bone formation studies. The osteogenic phenotype of cultured cell-scaffold constructs was heightened with a sol-gel derived titania coating, but not with a mixed titania-silica coating. The latter coating also resulted in delayed ectopic bone formation in bone marrow stromal cell seeded scaffolds. However, the better bone contact in early implantation times and more even bone tissue distribution at later times indicated enhanced osteoconductivity of both the coated scaffold types. Overall, the most promising bone engineering results were obtained with titania coated fiber meshes. Elastic and biodegradable poly(ε-caprolactone/D,L-lactide) based scaffolds were also developed in this study. The degradation rates of the scaffolds in vitro were governed by the hydrophilicity of the polymer matrix, and the porous architecture was controlled by the amount and type of porogen used. A continuous phase macroporosity was obtained using a novel CaCl2 • 6H2O porogen. Dynamic culture conditions increased cell invasion, but decreased cell numbers and osteogenicity, within the scaffolds. Osteogenic differentiation in static cultures and ectopic bone formation in cell seeded scaffolds were enhanced in composites, with 30 wt-% of bioactive glass filler.

Repair of segmental bone defects with fiber-reinforced composite: a study of material development and an animal model on rabbits

The Repair of segmental defects in load-bearing long bones is a challenging task because of the diversity of the load affecting the area; axial, bending, shearing and torsional forces all come together to test the stability/integrity of the bone. The natural biomechanical requirements for bone restorative materials include strength to withstand heavy loads, and adaptivity to conform into a biological environment without disturbing or damaging it. Fiber-reinforced composite (FRC) materials have shown promise, as metals and ceramics have been too rigid, and polymers alone are lacking in strength which is needed for restoration. The versatility of the fiber-reinforced composites also allows tailoring of the composite to meet the multitude of bone properties in the skeleton. The attachment and incorporation of a bone substitute to bone has been advanced by different surface modification methods. Most often this is achieved by the creation of surface texture, which allows bone growth, onto the substitute, creating a mechanical interlocking. Another method is to alter the chemical properties of the surface to create bonding with the bone – for example with a hydroxyapatite (HA) or a bioactive glass (BG) coating. A novel fiber-reinforced composite implant material with a porous surface was developed for bone substitution purposes in load-bearing applications. The material’s biomechanical properties were tailored with unidirectional fiber reinforcement to match the strength of cortical bone. To advance bone growth onto the material, an optimal surface porosity was created by a dissolution process, and an addition of bioactive glass to the material was explored. The effects of dissolution and orientation of the fiber reinforcement were also evaluated for bone-bonding purposes. The Biological response to the implant material was evaluated in a cell culture study to assure the safety of the materials combined. To test the material’s properties in a clinical setting, an animal model was used. A critical-size bone defect in a rabbit’s tibia was used to test the material in a load-bearing application, with short- and long-term follow-up, and a histological evaluation of the incorporation to the host bone. The biomechanical results of the study showed that the material is durable and the tailoring of the properties can be reproduced reliably. The Biological response - ex vivo - to the created surface structure favours the attachment and growth of bone cells, with the additional benefit of bioactive glass appearing on the surface. No toxic reactions to possible agents leaching from the material could be detected in the cell culture study when compared to a nontoxic control material. The mechanical interlocking was enhanced - as expected - with the porosity, whereas the reinforcing fibers protruding from the surface of the implant gave additional strength when tested in a bone-bonding model. Animal experiments verified that the material is capable of withstanding load-bearing conditions in prolonged use without breaking of the material or creating stress shielding effects to the host bone. A Histological examination verified the enhanced incorporation to host bone with an abundance of bone growth onto and over the material. This was achieved with minimal tissue reactions to a foreign body. An FRC implant with surface porosity displays potential in the field of reconstructive surgery, especially regarding large bone defects with high demands on strength and shape retention in load-bearing areas or flat bones such as facial / cranial bones. The benefits of modifying the strength of the material and adjusting the surface properties with fiber reinforcement and bone-bonding additives to meet the requirements of different bone qualities are still to be fully discovered.

Managing material flows and improving performance in a component supplier’s internal supply chain

Tämä diplomityö tehtiin osana Componenta Cast Componentsin kolmivuotista toimitusketjujen kehitysprojektia. Työn tavoitteena oli kuvata tyypillinen yrityksen sisäinen toimitusketjuprosessi ja tehdä alustava suorituskykyanalyysi valimon ja konepajan väliseen logistiseen prosessiin liittyen. Tarkoituksena oli myös löytää kehityskohteita materiaali- ja tietovirtojen hallinnassa näiden tuotantoyksiköiden välillä. Logistiikkaan, toimitusketjujen hallintaan ja toimitusketjun suorituskyvyn mittaamiseen liittyvän kirjallisuustutkimuksen sekä käytännön perusteella valittiin sopivat analyysimenetelmät. Näitä menetelmiä hyödynnettiin tilaustoimitus – prosessin kuvaamisessa sekä suorituskyvyn analysoinnissa yrityksen sisäisessä toimitusketjussa. Luonnollisena jatkona kehitettiin ja pantiin käytäntöön toimitusketjua synkronoiva imutyyppinen tuotannon- ja materiaalinohjausmenetelmä. Diplomityöprojektin aikana kehitettiin myös apuvälineet käyttöönotetun menetelmän asianmukaista hyödyntämistä varten. Diplomityöprojektissa otettiin ensimmäiset askeleet kohti integroitua sisäistä toimitusketjua. Uuden tuotannon- ja materiaalinohjausmenetelmän standardisointi muihin menetelmiin yhdistettynä, sekä toimitusketjun avainmittarien jatkokehitys on jo alkanut. Läpimenoaikoja lyhentämällä ja synkronoidun, läpinäkyvän kysyntä-tarjontaketjun avulla integroitumisen astetta voidaan nostaa edelleen. Poikkiorganisatorinen kehitys ja johtaminen toimitusketjussa on avainedellytys menestykseen.

Safety Culture and Maritime Personnel’s Safety Attitudes: Interview Report

”METKU –projektissa” (Merenkulun turvallisuuskulttuurin kehittäminen) tutkitaan kansainvälisen turvallisuusjohtamiskoodin (ISM-koodin) vaikutuksia merenkulun turvallisuuteen ja etsitään kehittämiskohteita merenkulun turvallisuusjohtamisen parantamiseksi. Tämä haastatteluraportti on laadittu METKU –projektin yhteistyössä työpakettien 1 ja 2 kesken. Tähän raporttiin haastateltiin yhteensä 94 merenkulun ammattilaista. Suurimman osan haastateltavista muodostivat aktiiviset merenkulkijat: miehistön jäsenet, päällystö ja alusten päälliköt. Haastattelukohteena oli seitsemän suomalaista varustamoa. Haastatteluissa kerättiin merenkulkijoiden kokemuksia ja mielipiteitä ISM-koodin vaikutuksesta heidän käytännön työhönsä. Suomalaiset merenkulkijat uskovat, että tänä päivänä varustamoiden johtajat ovat hyvin sitoutuneita turvallisuuteen. Myös miehistön asenteet turvallisuuteen ovat ISM-koodin käytön myötä parantuneet. Haasteltavien yhteinen huoli kohdistui jatkuvan parantamisen toimivuuteen. Kaikki haastatellut ryhmät olivat samaa mieltä siitä, että poikkeamien raportointi ei ISMkoodin vaatimuksesta huolimatta toimi kunnolla. ISM-koodin käyttöön otosta on ollut merenkululle selkeää hyötyä. Haastateltavat esittivät hyötyinä parantuneen yhteistyön ja tiedonkulun alusten ja varustamon välillä sekä sen, että merenkulun toiminnan laatu on parantunut. Monet haastateltavat korostivat, että ISM-koodin selkeät turvallisuusvastuut yhtiölle on ollut merkittävä hyöty. Itse ISM-koodiin merenkulkijoilla ei ollut juurikaan huomauttamista. Sen sijaan turvallisuusjohtamisen käytännön toteutuksessa nähtiin parantamisen varaa. ISMkoodin aiheuttamina ongelmina mainittiin mm. lisääntynyt byrokratia ja liian monimutkaiset ja yksityiskohtaiset turvallisuuskäsikirjat. Monet haastateltavat toivovat, että ISM-koodin käytännön soveltamiseen laadittaisiin ohjeita.

“Between publication culture and funder mandates - What is the future for disciplinary repositories?”

Workshop at Open Repositories 2014, Helsinki, Finland, June 9-13, 2014

Why are some companies more successful than others? An exploration into organizational culture and dynamic capabilities

Why are some companies more successful than others? This thesis approaches the question by enlisting theoretical frameworks that explain the performance with internal factors, deriving from the resource-based view, namely the dynamic capabilities approach. To deepen the understanding of the drivers and barriers towards developing these higher order routines aiming at improving the operational level routines, this thesis explores the organisational culture and identity research for the microfoundational antecedents that might shed light on the formation of the dynamic capabilities. The dynamic capabilities framework in this thesis strives to take the theoretical concept closer to practical applicability. This is achieved through creation of a dynamic capabilities matrix, consisting of four dimensions often encountered in dynamic capabilities literature. The quadrants are formed along internal-external and resources-abilities axes, and consist of Sensing, Learning, Reconfiguration and Partnering facets. A key element of this thesis is the reality continuum, which illustrates the different levels of reality inherent in any entity of human individuals. The theoretical framework constructed in the thesis suggests a link between the collective but constructivist understanding of the organisation and both the operational and higher level routines, evident in the more positivist realm. The findings from three different case organisations suggest that the constructivist assumptions inherent to an organisation function as a generative base for both drivers and barriers towards developing dynamic capabilities. From each organisation one core assumption is scrutinized to identify its connections to the four dimensions of the dynamic capabilities. These connections take the form of drivers or barriers – or have the possibility to develop into one or the other. The main contribution of this thesis is to show that one key for an organisation to perform well in a turbulent setting, is to understand the different levels of realities inherent in any group of people. Recognising the intangible levels gives an advantage in the tangible ones.

Animals in an Urban Context. A Zooarchaeological study of the Medieval and Post-Medieval town of Turku

The aim of this study is to explore the role and importance of different animal species in Turku through an analysis of osteological data and documentary evidence. The osteological material used in this study is derived from two town plots in Turku dating from the 13th century to the 19th century. The osteological material deposited in Turku represents animals bred both in the town and in the surrounding landscape. Animal husbandry in SW-Finland can also be examined through a number of historical documents. The importance of animals in Turku and its hinterland are closely connected and therefore the roles of the animals in both urban and rural settings are examined. The study has revealed the complexity of the depositional patterns in medieval and post-medieval Turku. In the different areas of Turku, characteristic patterns in the osteological material and different deposit types were evident. These patterns are reflections of the activities and therefore of the lifestyles practiced in Turku. The results emphasise the importance of context- awareness in the study of material culture from archaeological sites. Both the zooarchaeological and historical sources indicate that cattle were important in animal husbandry in Turku from the Middle Ages up to the 19th century. Sheep were the second most common species. When taking into consideration the larger size of cattle, the dominance of these animals when it come to meat consumption seems clear even in those phases where sheep bones are more abundant. Pig is less abundant in the material than either cattle or sheep and their importance for subsistence was probably fairly modest, albeit constant. Goats were not abundant in the material. Most of the identified goat bones came from low utility body parts (e.g. skulls and lower extremities), but some amount of goat meat was also consumed. Wild species were of minor importance when it came to consumption practices in Turku. The changes in Turku’s animal husbandry patterns between the medieval and post medieval periods is reflected in the change in age of the animals slaughtered, which was part of a wider pattern seen in North- and Central Europe. More mature animals are also present in the assemblages. This pattern is related to the more pronounced importance of cattle as a manure producer and a draught animal as a result of the intensification of crop cultivation. This change seems to occur later in Finland than in the more Southerly regions, and indeed it did not necessarily take hold in all parts of the country.

Role of culture in knowledge transfer and sharing - case ERP implementation

The main objective of this study was to examine how culture influences knowledge transfer and sharing within multicultural ERP project implementation in China. The main interest was to explain how national culture and knowledge are linked by understanding how culture influences knowledge transfer and sharing in a project organization. The other objective of this work was to discuss what Chinese cultural characteristic inhibit and en-hance knowledge sharing in ERP project. The perspective of this study was qualitative and the empirical material was collected from theme interviews among Stora Enso employees. Conclusion of this thesis is that Finns have a very direct style of communication and sharing knowledge whereas Chinese respect face shaving and indirect communication. Another conclusion is that knowledge sharing does not “just happen”, it is needed that project members understand national culture to get all project members commitment to project. In China most important is understand local business processes and understand role of trust and guanxi.

Managing the change of organizational culture in cross-border mergers and acquisitions: The role of post-acquisition integration in organizational culture change

Over the years, cross-border mergers and acquisitions have become a popular strategic option for variety of firms. Companies often seek rapid growth through acquiring potentially valuable enterprises or attempting to enhance their organization’s profitability by merging with other firms. However, managing the change of organizational culture is a major managerial challenge as companies often confront difficulties when merging two previously autonomous organizational cultures into one, joint organizational culture. Therefore, the purpose of this study is to increase understanding related to the challenges and possibilities concerning the management of organizational culture change in cross-border mergers and acquisitions. The research question “How to manage the change of organizational culture in cross-border mergers and acquisitions?” is analysed in relation to the theories presented in this thesis regarding organizational culture, organizational change and acculturation as well as in relation with the collected empirical data. The research question is divided into three sub-questions according to the following: (1) “What is the role of organizational culture in organizations?”, (2) “How to manage organizational change in mergers and acquisitions?” and (3) “How to manage organizational culture change through acculturation?”. The thesis is conducted as a qualitative case study research including three personal interviews and one group interview. The interviews were conducted as a combination of semi-structured and unstructured interviews. Theories related to organizational culture, the management of change as well as acculturation are studied and further analysed in relation to empirical material collected by the researcher. Research findings indicate that that several factors can influence the success of managing the organizational culture change in cross-border mergers and acquisitions. Factors such as defining the preferred acculturation model prior the merger; managing the resistance of change; open communication; acknowledgement of local culture and cultural differences; involvement of personnel in change processes; as well as the formulation and implementation of comprehensive change plans proved to be important factors with relation to successful management of organizational culture change

Thermoplastic bioactive composite – with special reference to dissolution behaviour and tissue response

Bioactive glasses are surface-active ceramic materials which support and accelerate bone growth in the body. During the healing of a bone fracture or a large bone defect, fixation is often needed. The aim of this thesis was to determine the dissolution behaviour and biocompatibility of a composite consisting of poly(ε-caprolactone-co-DL-lactide) and bioactive glass (S53P4). In addition the applicability as an injectable material straight to a bone defect was assessed. In in vitro tests the dissolution behaviour of plain copolymer and composites containing bioactive glass granules was evaluated, as well as surface reactivity and the material’s capability to form apatite in simulated body fluid (SBF). The human fibroblast proliferation was tested on materials in cell culture. In in vivo experiments, toxicological tests, material degradation and tissue reactions were tested both in subcutaneous space and in experimental bone defects. The composites containing bioactive glass formed a unified layer of apatite on their surface in SBF. The size and amount of glass granules affected the degradation of polymer matrix, as well the material’s surface reactivity. In cell culture on the test materials the human gingival fibroblasts proliferated and matured faster compared with control materials. In in vitro tests a connective tissue capsule was formed around the specimens, and became thinner in the course of time. Foreign body cell reactions in toxicological tests were mild. In experimental bone defects the specimens with a high concentration of small bioactive glass granules (<45 μm) formed a dense apatite surface layer that restricted the bone ingrowth to material. The range of large glass granules (90-315 μm) with high concentrations formed the best bonding with bone, but slow degradation on the copolymer restricted the bone growth only in the superficial layers. In these studies, the handling properties of the material proved to be good and tissue reactions were mild. The reactivity of bioactive glass was retained inside the copolymer matrix, thus enabling bone conductivity with composites. However, the copolymer was noticed to degradate too slowly compared with the bone healing. Therefore, the porosity of the material should be increased in order to improve tissue healing.