Primary angiosarcoma of the heart

Primary hemangioendotheliosarcoma is the least common form of sarcoma of the heart, itself an uncommon tumor. A review of most of the reported cases is presented. This study revealed that although the syndrome produced by cardiac sarcoma point to a strikingly characteristic picture, the diagnosis is almost always confused, especially with pericardial inflammatory diseases, and delayed. Successful treatment generally has not been available. This is the only case we know of that has been treated by resection utilizing cardiopulmonary bypass. The appearance of metastases in unusual locations in our patient, despite total excision of the primary, suggests tumor embolization during the bypass and the need for intra-operative chemotherapy, as well as such treatment before or after surgery.     

Institutional Theory as a Framework for Analyzing Conflicts on Global Projects

Global construction projects that involve collaboration between participants from multiple countries often result in unique challenges, and costs due to cross-national interactions. Case studies performed to investigate the cross-national interactions and tensions present on global projects suggest that institutional differences—differences in workplace norms, legal regulations, and cultural values—contribute to these costs. We demonstrate how institutional theory—a branch of organizational theory—can comprehensively describe the cross-national challenges on global projects. We show how this theory can help practitioners to more accurately classify the cross-national issues they encounter, determine the causes behind the conflicts, and judge the relative ease with which each type of conflict can be resolved. However, there are gaps in the extant application of institutional theory that prevent us from predicting institutional conflicts on global projects and devising solution strategies. These gaps are identified and a research trajectory to understand them is proposed. This paper is aimed at starting a much-needed dialogue on the mitigation of cross-national issues on global projects, and not as a demonstration of methods to eliminate all cross-national conflicts.     

Patterns of annual citation of highly cited articles and the prediction of their citation ranking: A comparison across subjects

High citation is associated with research quality and consequently findings on highly cited articles are useful to increase understanding of the factors that produce high quality research. This study explores highly cited articles in six subjects, focusing on late citation and peak citation years. Longitudinal citation patterns were found to be highly varied and, on average, different from the remaining articles in each subject. For four of the six subjects, there is a correlation of over 0.42 between the percentage of early citations and total citation ranking but more highly ranked articles had a lower percentage of early citations. Surprisingly, for highly cited articles in all six subjects the prediction of citation ranking of from the sum of citations during their first six years was less accurate than prediction using the sum of the citations for only the fifth and sixth year.     

Evaluation of serum inhibin A as a surveillance marker after conservative management of tubal pregnancy

Tubal pregnancy is now commonly managed by laparoscopic salpingostomy or systemic methotrexate. A disadvantage of such conservative management is the need for appropriate follow-up, with serial measurement of serum concentrations of human chorionic gonadotrophin (HCG), to exclude persistent ectopic pregnancy (PEP). Concentrations of inhibin A, also a placental product, are significantly increased during pregnancy and the half-life of inhibin A is significantly shorter than that of HCG. To assess the suitability of inhibin A as a marker of PEP, we studied 16 women who had undergone surgery for a tubal pregnancy, measuring HCG and inhibin during follow-up. The mean +/- SEM time taken to achieve non-pregnant concentrations of inhibin A was significantly shorter than for HCG (4.2 +/- 0.8 days versus 21.6 +/- 4.4 days respectively; P < 0.001 Wilcoxon signed rank test). However, in all women the inhibin A concentration increased rapidly after reaching a nadir, reflecting the return of ovarian function, complicating the interpretation of results. In four women inhibin A was almost undetectable preoperatively, while the corresponding HCG concentration was high. These data suggest that inhibin A will not be a useful marker for PEP but that it may provide a more accurate preoperative assessment of trophoblast viability than HCG, thereby improving management.     

Cutting edge: antigen-dependent regulation of telomerase activity in murine T cells

Telomeres, structures on the ends of linear chromosomes, function to maintain chromosomal integrity. Telomere shortening occurs with cell division and provides a mechanism for limiting the replicative potential of normal human somatic cells. Telomerase, a ribonucleoprotein enzyme, synthesizes telomeric repeats on chromosomal termini, potentially extending the capacity for cell division. The present study demonstrates that resting T cells express little/no activity, and optimal Ag-specific induction of telomerase activity in vitro requires both TCR and CD28-B7 costimulatory signals. Regulation of telomerase in T cells during in vivo Ag-dependent activation was also assessed by adoptive transfer of TCR transgenic T cells and subsequent Ag challenge. Under these conditions, telomerase was induced in transgenic T cells coincident with a phase of extensive clonal expansion. These findings suggest that telomerase may represent an adoptive response that functions to preserve replicative potential in Ag-reactive lymphocytes.     

LVT: a layered verification technique for distributed computing systems

This paper presents a layered verification technique, called LVT, for the verification of distributed computing systems with multiple component layers. Each lower layer in such a system provides services in support of functionality of the higher layer. By taking a very general view of programming languages as interfaces of systems, LVT treats each layer in a distributed computing system as a distributed programming language. Each relatively higher‐level language in the computing system is implemented in terms of a lower‐level language. The verification of each layer in a distributed computing system can then be viewed as the verification of implementation correctness for a distributed language. This paper also presents the application of LVT to the verification of a distributed computing system, which has three layers: a small high‐level distributed programming language; a multiple processor architecture consisting of an instruction set and system calls for inter‐process message passing; and a network interface. Programs in the high‐level language are implemented by a compiler mapping from the language layer to the multiprocessor layer. System calls are implemented by network services. LVT and its application demonstrate that the correct execution of a distributed program, most notably its inter‐process communication, is verifiable through layers. The verified layers guarantee the correctness of (1) the compiled code that makes reference to operating system calls, (2) the operating system calls in terms of network calls, and (3) the network calls in terms of network transmission steps. The specification and verification involved are carried out by using the Cambridge Higher Order Logic (HOL) theorem proving system. Copyright © 1999 John Wiley & Sons, Ltd.