The human cleavage stage embryo is a cradle of chromosomal rearrangements.

The first cell cycles following in vitro fertilization (IVF) of human gametes are prone to chromosome instability. Many, but often not all, blastomeres of an embryo acquire a genetic makeup during cleavage that is not representative of the original zygotic genome. Whole chromosomes are missegregated, but also structural rearrangements of chromosomes do occur in human cleavage stage embryogenesis following IVF. Analysis of pre- and postnatal DNA samples indicates that the in vivo human conceptions also endure instability of chromosome number and structure during cleavage of the fertilized oocyte. This embryonic chromosome instability not necessarily undermines normal human development, but may lead to a spectrum of conditions, including loss of conception, genetic disease and genetic variation development. In this review, the structural instability of chromosomes during human cleavage stage embryogenesis is catalogued, channeled into etiologic models and linked to genomic profiles of healthy and diseased newborns.

PGD for a complex chromosomal rearrangement by array comparative genomic hybridization.

Patients carrying a chromosomal rearrangement (CR) have an increased risk for chromosomally unbalanced conceptions. Preimplantation genetic diagnosis (PGD) may avoid the transfer of embryos carrying unbalanced rearrangements, therefore increasing the chance of pregnancy. Only 7-12 loci can be screened by fluorescence in situ hybridization whereas microarray technology can detect genome-wide imbalances at the single cell level. We performed PGD for a CR carrier with karyotype 46,XY,ins(3;2)(p23;q23q14.2),t(6;14)(p12.2;q13) using array comparative genomic hybridization. Selection of embryos for transfer was only based on copy number status of the chromosomes involved in both rearrangements. In two ICSI-PGD cycles, nine and seven embryos were analysed by array, leaving three and one embryo(s) suitable for transfer, respectively. The sensitivity and specificity of single cell arrays was 100 and 88.8%, respectively. In both cycles a single embryo was transferred, resulting in pregnancy following the second cycle. The embryo giving rise to the pregnancy was normal/balanced for the insertion and translocation but carried a trisomy 8 and nullisomy 9 in one of the two biopsied blastomeres. After 7 weeks of pregnancy the couple miscarried. Genetic analysis following hystero-embryoscopy showed a diploid (90%)/tetraploid (10%) mosaic chorion, while the gestational sac was empty. No chromosome 8 aneuploidy was detected in the chorion, while 8% of the cells carried a monosomy for chromosome 9. In summary, we demonstrate the feasibility and determine the accuracy of single cell array technology to test against transmission of the unbalanced meiotic products that can derive from CRs. Our findings also demonstrate that the genomic constitution of extra-embryonic tissue cannot necessarily be predicted from the copy number status of a single blastomere.

Optimizing physicians' instruction of PACS through e-learning: cognitive load theory applied.

This article outlines the strategy used by our hospital to maximize the knowledge transfer to referring physicians on using a picture archiving and communication system (PACS). We developed an e-learning platform underpinned by the cognitive load theory (CLT) so that in depth knowledge of PACS' abilities becomes attainable regardless of the user's prior experience with computers. The application of the techniques proposed by CLT optimizes the learning of the new actions necessary to obtain and manipulate radiological images. The application of cognitive load reducing techniques is explained with several examples. We discuss the need to safeguard the physicians' main mental processes to keep the patient's interests in focus. A holistic adoption of CLT techniques both in teaching and in configuration of information systems could be adopted to attain this goal. An overview of the advantages of this instruction method is given both on the individual and organizational level.

[Do hospital physicians really want to go digital? --Acceptance of a picture archiving and communication system in a university hospital]. / Möchten Krankenhausärzte wirklich auf digitale Systeme umsteigen?--Die Akzeptanz gegenüber einem Bildarchivierungs- und Ubermittlungssystem in einer Universitätsklinik.

PURPOSE: Radiology departments are making the transition from analog film to digital images by means of PACS (Picture Archiving and Communication System). It is critical for the hospital that its physicians adopt and accept the new digital work method regarding radiological information. The aim of this study is to investigate hospital physicians' acceptance of PACS using questionnaires pre- and post-implementation and to identify main influencing factors. MATERIALS AND METHODS: The study was conducted in an 1169 bed university hospital. The UTAUT (Unified Theory of Acceptance and Use of Technology) questionnaire was administered at two times: one month pre-implementation (T1) and 1.5 years post-implementation (T2) of PACS, targeting all hospital physicians with the exemption of radiologists. The UTAUT scales (Behavioral Intention BI; Facilitating Conditions FC; Effort Expectancy EE; Performance Expectancy PE; Anxiety ANX; Social Influence SI; System Use USE; Attitude toward technology ATT; Self-Efficacy SE) were used to assess questions regarding: a) PACS' usefulness, b) PACS' ease of learning/using, c) PACS support availability, d) the perceived pressure to use PACS, e) physicians' attitude towards PACS and f) physicians' intention to use and actual use of PACS. RESULTS: At T 1 scale ratings were positive toward the PACS implementation. The ratings on all scales with the exception of self-efficacy improved at T 2. Regression analysis revealed that the key factor for intention to use PACS at T 1 was the usefulness of PACS, while the availability and awareness of support was its most important predictor at T 2. Overall, PE was the best predictor of BI, but all four UTAUT-determinants (PE, FC, EE and SI) were salient for its prediction. Variance explained in BI ranged from 31 to 37 % while variance explained in USE was very low (3 %). CONCLUSION: The implementation of PACS has succeeded. At T 1 the physicians were welcoming PACS and this was confirmed at T 2. Experience with PACS led to an overall improved attitude toward PACS. The key factors for physicians' intentions to use PACS were the usefulness of PACS (at T 1 and overall) and the availability of support (at T 2).

User acceptance of a picture archiving and communication system. Applying the unified theory of acceptance and use of technology in a radiological setting.

OBJECTIVE: The aim of this study is to gain insight into the individual user acceptance of PACS by the radiology department staff of the Ghent University Hospital. Hereto a basic--direct effects only--form of UTAUT was assessed. METHODS: Ninety-four questionnaires were distributed and 56 usable questionnaires were returned (19 radiologists - 37 technologists). The questionnaire consisted of scales of Venkatesh et al. [13] for performance expectancy (PE), effort expectancy (EE), facilitating conditions (FC), social influence (SI), self-efficacy (SE), attitude (ATT), anxiety (ANX) and behavioral intention (BI), and a scale of Moore et al. [22] to assess the perceived voluntariness of PACS-use. RESULTS: The reliability of all scales, except FC and voluntariness, was acceptable to good. The voluntariness scale was divided into a mandatoriness (MAN) and a voluntariness (VOL) measure. Both radiologists and technologists seem to welcome PACS, with radiologists having higher ratings on PE, EE, ATT, VOL and BI. Only PE and FC were salient for predicting BI, while EE and SI were not salient. Variance explained in behavioral intention to use PACS was 48%. CONCLUSION: Both radiologists and technologists were positive towards PACS and had strong intentions to use PACS. As other healthcare professionals, they appear to make their technology acceptance decision independent from their superiors, hereby focusing on usefulness rather than on ease of use. It is also important that support is supplied. Basic UTAUT is an adequate model to assess technology acceptance in a radiological setting.

Design and implementation of an open source indexing solution for a large set of radiological reports and images.

This paper hopes to share the insights we experienced during designing, building, and running an indexing solution for a large set of radiological reports and images in a production environment for more than 3 years. Several technical challenges were encountered and solved in the course of this project. One hundred four million words in 1.8 million radiological reports from 1989 to the present were indexed and became instantaneously searchable in a user-friendly fashion; the median query duration is only 31 ms. Currently, our highly tuned index holds 332,088 unique words in four languages. The indexing system is feature-rich and language-independent and allows for making complex queries. For research and training purposes it certainly is a valuable and convenient addition to our radiology informatics toolbox. Extended use of open-source technology dramatically reduced both implementation time and cost. All software we developed related to the indexing project has been made available to the open-source community covered by an unrestricted Berkeley Software Distribution-style license.

Role of cardiac myocyte tissue factor in heart hemostasis.

BACKGROUND: The tissue-specific pattern of tissue factor (TF) expression suggests that it plays a major role in the hemostatic protection of specific organs, such as the heart and lung. In support of this notion, we found that mice expressing very low levels of TF exhibit hemostatic defects in the heart and lung. Hemosiderosis and fibrosis are observed in the hearts of all low TF mice as early as 3 months of age. In contrast, TF(+/-) mice expressing approximately 50% of wild-type levels of TF had no detectable hemostatic defects. OBJECTIVE AND METHODS: The objective of this study was to determine the threshold of TF that is required to maintain hemostasis under normal and pathologic conditions, and to investigate the specific role of cardiac myocyte TF in heart hemostasis using mice with altered levels of TF expression in cardiac myocytes. RESULTS: First, we found that mice with 20% of wild-type levels of TF activity in their hearts had hemosiderosis and fibrosis by 6 months of age. Secondly, mice with a selective deletion of the TF gene in cardiac myocytes had a mild hemostatic defect under normal conditions but exhibited a significant increase in hemosiderosis and fibrosis after challenge with isoproterenol. Finally, we showed that cardiac myocyte-specific overexpression of TF abolished hemosiderin deposition and fibrosis in the hearts of low TF mice. CONCLUSIONS: Taken together, our results indicate that TF expression by cardiac myocytes is important to maintain heart hemostasis under normal and pathologic conditions.

Efficient male and female germline transmission of a human chromosomal vector in mice.

A small accessory chromosome that was mitotically stable in human fibroblasts was transferred into the hprt(-) hamster cell line CH and developed as a human chromosomal vector (HCV) by the introduction of a selectable marker and the 3' end of an HPRT minigene preceded by a loxP sequence. This HCV is stably maintained in the hamster cell line. It consists mainly of alphoid sequences of human chromosome 20 and a fragment of human chromosome region 1p22, containing the tissue factor gene F3. The vector has an active centromere, and telomere sequences are lacking. By transfecting a plasmid containing the 5' end of HPRT and a Cre-encoding plasmid into the HCV(+) hamster cell line, the HPRT minigene was reconstituted by Cre-mediated recombination and expressed by the cells. The HCV was then transferred to male mouse R1-ES cells and it did segregate properly. Chimeras were generated containing the HCV as an independent chromosome in a proportion of the cells. Part of the male and female offspring of the chimeras did contain the HCV. The HCV(+) F1 animals harbored the extra chromosome in >80% of the cells. The HCV was present as an independent chromosome with an active centromere and the human F3 gene was expressed from the HCV in a human-tissue-specific manner. Both male and female F1 mice did transmit the HCV to F2 offspring as an independent chromosome with properties similar to the original vector. This modified small accessory chromosome, thus, shows the properties of a useful chromosomal vector: It segregates stably as an independent chromosome, sequences can be inserted in a controlled way and are expressed from the vector, and the HCV is transmitted through the male and female germline in mice.

Validation of MR-based polymer gel dosimetry as a preclinical three-dimensional verification tool in conformal radiotherapy.

The aim of this work was to investigate MR-based polymer gel dosimetry as a three-dimensional (3D) dosimetry technique in conformal radiotherapy. A cylindrical container filled with polymer gel was placed in a water-filled torso phantom to verify a treatment plan for the conformal irradiation of a mediastinal tumor located near the esophagus. Magnetic resonance spin-spin relaxation rate images were acquired and, after calibration, converted to absorbed dose distributions. The dose maps were compared with dose distributions measured using radiographic film. The average root-mean-square structural deviation, for the complete dose distribution, amounted to less than 3% between gel and film dose maps. It may be expected that MR gel dosimetry will become a valuable tool in the verification of 3D dose distributions. The influence of imaging artifacts arising from eddy currents, temperature drift during scanning, and B1 field inhomogeneity on the dose maps was taken into account and minimized.

Genomic organization of human JAK2 and mutation analysis of its JH2-domain in leukemia.

The Janus kinase family of proteins, with four mammalian members (JAK1, JAK2, JAK3 and TYK2), plays an essential role in the signal transduction pathway from non-catalytic cytokine receptors to the nucleus. We recently reported the involvement of ETV6-JAK2 fusion genes in the development of leukemia of both lymphoid and myeloid origin. Dominant missense mutations of hopscotch, a Drosophila JAK homologue, causing leukemia-like defects were described. One of these mutations affected a conserved residue of the kinase- like JH2 domain and the introduction of this mutation in murine Jak2 resulted in the constitutional activation of its kinase activity. In order to further analyze its role in leukemogenesis, we cloned human JAK2 and determined its genomic organization. Twenty-four exons spanning a region of approximately 150 kb were identified. A mutation analysis of the exons 13 to 19, encoding the kinase-like JH2 domain failed to detect activating mutations in leukemia samples, suggesting that this is a rare event in human leukemia.