Bioactive ceramic-reinforced composites for bone augmentation

Biomaterials have been used to repair the human body for millennia, but it is only since the 1970s that man-made composites have been used. Hydroxyapatite (HA)-reinforced polyethylene (PE) is the first of the ‘second-generation’ biomaterials that have been developed to be bioactive rather than bioinert. The mechanical properties have been characterized using quasi-static, fatigue, creep and fracture toughness testing, and these studies have allowed optimization of the production method. The in vitro and in vivo biological properties have been investigated with a range of filler content and have shown that the presence of sufficient bioactive filler leads to a bioactive composite. Finally, the material has been applied clinically, initially in the orbital floor and later in the middle ear. From this initial combination of HA in PE other bioactive ceramic polymer composites have been developed

Human zona pellucida abnormalities:a genetic approach to the understanding of fertilization failure

Abstract Despite the development of assisted reproduction technologies and significant advances in reproductive biology and medicine over the years the cause of infertility remains unexplained in 10–20% of cases. The cause of infertility in these cases may be connected to problems in fertilization or implantation and genetic factors may play a part in this. The zona pellucida (ZP) is an extracellular matrix surrounding the oocyte and early-stage embryos. It is important for folliculogenesis, fertilization and implantation. In humans, it is composed of four known ZP glycoproteins that all show varying degrees of structural and functional roles in reproduction. The aim of the present study was to examine the role of zona pellucida genes in cases of total fertilization failure and zona anomalies, and to study their expression in human fetal and adult ovaries. A total of 34 sequence variations were detected in genes expressing the four human ZP proteins (ZP1–ZP4) among women with fertilization failure and those with varying degrees of zona anomalies in their oocytes. Most of the variations were known single nucleotide polymorphisms, while three were novel findings. Women with fertilization failure had a higher mean number of sequence variations in ZP1 and ZP3 when compared with controls. Some of the most frequent zona anomalies may be at least partly explained by sequence variations in ZP1–ZP4 genes. In fetal life, the expression of ZP3 protein and mRNA could already be detected as early as at the 11th week of gestation and it peaked at the 20th week, the time of primordial follicle formation. This suggests that components needed for zona matrix are already present well before the formation of the zona pellucida and may have a role in the development of primordial follicles. Expression of the transcription factor FIGLA (factor in the germline alpha) was increased at around the 20th week of gestation, supporting previous findings of its critical role in the initiation of folliculogenesis and primordial follicle formation. The present study adds to our knowledge on the currently still incomplete picture of formation of the ZP and fertilization in humans. Understanding the genetic background of infertile patients may help us to develop new tools not only to evaluate but also to improve their fertilization potential, and to choose the optimal treatment to achieve pregnancy.Tiivistelmä Diagnostiikan kehityksestä huolimatta hedelmättömyyden syy jää edelleen epäselväksi 10–20 %:ssa tapauksista. Niissä hedelmättömyyden taustalla voivat olla munasolun hedelmöittymiseen ja kohtuun kiinnittymiseen liittyvät ongelmat, jotka voivat osittain johtua geneettisistä syistä. Alkiokuori on munasolua ja varhaista alkiota ympäröivä rakenne, joka osallistuu munarakkulan kehittymiseen, munasolun hedelmöittymiseen ja alkion tarttumiseen kohdun limakalvolle. Ihmisellä alkiokuori muodostuu neljästä tunnetusta alkiokuoriproteiinista (ZP1–ZP4). Tutkimuksessa selvitettiin alkiokuoriproteiineja koodittavien geenien vaikutusta hedelmällisyyteen potilailla, joilla koeputkihedelmöitys ei ollut tuottanut yhtään hedelmöittynyttä munasolua (engl. total fertilization failure, TFF) tai joiden munasoluissa havaittiin alkiokuoren rakennemuutoksia (engl. zona anomalies, ZA). Lisäksi selvitettiin alkiokuoriproteiinien ja niiden lähetti-RNA:n esiintymistä sikiöiden ja aikuisten munasarjoissa. TFF- ja ZA-potilaiden alkiokuoriproteiineja koodittavista geeneistä löytyi yhteensä 34 nukleotidimuutosta. Muutoksista kolme oli uusia löydöksiä, mutta suurin osa oli ennalta tunnettuja yhden nukleotidin polymorfioita eli geneettisiä monimuotoisuuskohtia. TFF-potilailla havaittiin ZP1- ja ZP3-geeneissä keskimäärin enemmän polymorfioita kuin verrokeilla. Myös osa yleisimmistä alkiokuoren rakennemuutoksista voidaan mahdollisesti selittää ZP1–ZP4-geeneistä löytyneillä polymorfioilla. Sikiöllä ZP3:n ilmentyminen oli havaittavissa jo 11. raskausviikolla, mutta voimakkainta se oli primordiaalivaiheen munarakkuloiden muodostumisen aikaan 20. raskausviikolla. Tämä voi viitata siihen, että ZP3 saattaa osallistua primordiaalivaiheen munarakkulan kehittymiseen ennen varsinaisen alkiokuoren muodostumista. ZP-geenien säätelytekijän FIGLA:n esiintyminen lisääntyi 20. raskausviikolla, mikä tukee aikaisempia havaintoja FIGLA:n merkityksestä munarakkulan kehittymisen aktivaatiossa ja primordiaalivaiheen munarakkuloiden muodostumisessa. Tämä tutkimus tuo lisätietoa alkiokuoren merkityksestä munasolun hedelmöittymisessä ja syventää tietämystämme alkiokuoren muodostumisesta ihmisellä. Hedelmättömyyden taustalla olevien geneettisten tekijöiden tunteminen voi parantaa lapsettomuuspotilaiden hedelmällisyyden arviointia ja auttaa löytämään heille parhaiten sopivan hoidon

Development of new B2B venture corporate brand identity:a narrative performance approach

Abstract The development and role of brand identity in new B2B ventures is not well explored despite the challenge for such organisations in establishing reputational legitimacy. Previous research defines corporate brand identity as stable and endogenous to the organisation based either on the reputational capital of the organisation or the founder. We challenge this view in this paper from a conceptual and empirical perspective. Combining narrative theory and performativity theory this article suggests brand identity develops as a narrative performance. The study employs a narrative case analysis of interviews and archival data generated during a three-year period to examine the development of corporate brand over time. This study shows that the development of corporate brand identity and the context of the development of new B2B venture are closely intertwined processes and provides a framework for understanding the phenomenon. Brand identity is not a stable core emanating from inside the company but develops over time through a reciprocal sensemaking and dynamic interactions between company and the key external stakeholders in its context. We conclude that brand identity is built not only upon the reputational capital of past behaviours but of the brand itself as it explores and interacts within its brand eco-system