John D. Olson

Bio: John D. Olson is an academic researcher from University of Texas Health Science Center at San Antonio. The author has contributed to research in topics: Partial thromboplastin time & Ristocetin. The author has an hindex of 30, co-authored 83 publications receiving 2917 citations. Previous affiliations of John D. Olson include University of Michigan & University of Iowa.

College of American Pathologists Conference XXXI on laboratory monitoring of anticoagulant therapy: laboratory monitoring of unfractionated heparin therapy

Abstract: Objective To review the state of the art as reflected in the medical literature and the consensus opinion of recognized experts in the field regarding the laboratory monitoring of unfractionated heparin therapy. Data sources, extraction and synthesis The authors made an extensive review of the literature. The draft manuscript was circulated to every participant in the consensus conference prior to the convening of the conference. Extensive discussion concerning all of the issues addressed in the manuscript as well as the resulting recommendations occurred. This information was then used to revise the manuscript into its final form. Conclusions The resulting manuscript has 23 specific recommendations regarding preanalytic, analytic, and postanalytic phases of monitoring and testing for complications related to unfractionated heparin therapy. This report contains detailed discussion of these recommendations and includes literature citations that support them. A number of issues for which consensus could not be reached are also discussed. A method is provided to assist laboratories, particularly small laboratories, in providing clinicians with an appropriate therapeutic range for the activated partial thromboplastin time, the most commonly used test in monitoring heparin therapy.

Packed red cells in acute blood loss: dilutional coagulopathy as a cause of surgical bleeding.

Abstract: The purpose of this study was: 1) to define coagulation abnormalities in patients who receive red cell concentrates rather than whole blood for large volume blood loss (greater than 0.5 blood volume); and 2) to determine when coagulation abnormalities lead to increased bleeding in the massively transfused surgical patient. We studied 32 ASA physical status I or II patients (mean age 15.6 +/- 2.3 yr) who lost more than 50% of their blood volume during elective posterior spinal stabilization. Crystalloid solutions and packed red cell concentrates were used to replace blood and fluid losses. Invasive hemodynamic measures, urinary output, and serial hematocrit determinations were used to help maintain a constant intravascular volume and confirm the estimates of blood loss. The quality of hemostasis was assessed during operation. In 15 of the 32 patients, surgical hemostasis remained effective throughout posterior spinal fusion. A coagulation profile (prothrombin time [PT] and activated partial thromboplastin time [aPTT], platelet count, and fibrinogen) was measured at the conclusion of operation in these patients. In 17 patients, increased surgical bleeding as a result of decreased clot formation and increased bleeding from the wound was present. In these 17 patients at the time increased bleeding was diagnosed, hemostatic tests (PT, aPTT, fibrinogen, platelet count, and coagulation factor assays V, VIII, and IX) were obtained.(ABSTRACT TRUNCATED AT 250 WORDS)

Fetal hemorrhage and platelet dysfunction in SLP-76–deficient mice

Abstract: The adapter protein SLP-76 is expressed in T lymphocytes and hematopoietic cells of the myeloid lineage, and is known to be a substrate of the protein tyrosine kinases that are activated after ligation of the T-cell antigen receptor Transient overexpression of SLP-76 in a T-cell line potentiates transcriptional activation after T-cell receptor ligation, while loss of SLP-76 expression abrogates several T-cell receptor–dependent signaling pathways Mutant mice that lack SLP-76 manifest a severe block at an early stage of thymocyte development, implicating SLP-76 in signaling events that promote thymocyte maturation While it is clear that SLP-76 plays a key role in development and activation of T lymphocytes, relatively little is understood regarding its role in transducing signals initiated after receptor ligation in other hematopoietic cell types In this report, we describe fetal hemorrhage and perinatal mortality in SLP-76–deficient mice Although megakaryocyte and platelet development proceeds normally in the absence of SLP-76, collagen-induced platelet aggregation and granule release is markedly impaired Furthermore, treatment of SLP-76–deficient platelets with collagen fails to elicit tyrosine phosphorylation of phospholipase C-γ2 (PLC-γ2), suggesting that SLP-76 functions upstream of PLC-γ2 activation These data provide one potential mechanism for the fetal hemorrhage observed in SLP-76–deficient mice and reveal that SLP-76 expression is required for optimal receptor-mediated signal transduction in platelets as well as T lymphocytes

Coagulation changes during packed red cell replacement of major blood loss.

Abstract: A greater proportion of blood replacement needs are being met by packed red cell concentrates rather than whole blood in situations of major blood loss. Twelve patients, who required major blood replacement during elective surgery, were studied to determine the changes in coagulation when packed red cells were used to replace major blood loss. In addition, the coagulation abnormalities present at the time an observer noted excessive bleeding were determined. Prior to blood product replacement and after the estimated loss of each 0.3 blood volume, coagulation tests were obtained including prothrombin time (PT), partial thromboplastin time (aPTT), platelet count, thrombin time (TT), fibrinogen levels, and assays of coagulation Factors V, VIII, and IX. Coagulation tests were repeated when clinical hemostasis was judged inadequate by the anesthesiologist and attending surgeon. Significant decreases in platelet count, fibrinogen levels, and Factor V, VIII, and IX levels occurred as increasing blood volumes were replaced. Increases in PT and aPTT above control occurred in nine of the 12 patients prior to replacement of 1 blood volume; none of the nine patients had increased clinical bleeding. In four of seven patients who had blood replacement of greater than 1 blood volume, increased clinical bleeding was noted by the observer. Platelet counts were less than 100,000/mm3 in each of these four patients, and a platelet concentrate obtained by pheresis of a single donor was administered. In two of the four patients platelet counts increased, but clinical bleeding did not resolve.(ABSTRACT TRUNCATED AT 250 WORDS)

The Human Side of Enterprise.

Abstract: \"What are your assumptions (implicit as well as explicit) about the most effective way to manage people?\" So began Douglas McGregor in this 1960 management classic. It was a seemingly simple question he asked, yet it led to a fundamental revolution in management. Today, with the rise of the global economy, the information revolution, and the growth of knowledge-driven work, McGregor's simple but provocative question continues to resonate-perhaps more powerfully than ever before. Heralded as one of the most important pieces of management literature ever written, a touchstone for scholars and a handbook for practitioners, The Human Side of Enterprise continues to receive the highest accolades nearly half a century after its initial publication. Influencing such major management gurus such as Peter Drucker and Warren Bennis, McGregor's revolutionary Theory Y-which contends that individuals are self-motivated and self-directed-and Theory X-in which employees must be commanded and controlled-has been widely taught in business schools, industrial relations schools, psychology departments, and professional development seminars for over four decades. In this special annotated edition of the worldwide management classic, Joel Cutcher-Gershenfeld, Senior Research Scientist in MIT's Sloan School of Management and Engineering Systems Division, shows us how today's leaders have successfully incorporated McGregor's methods into modern management styles and practices. The added quotes and commentary bring the content right into today's debates and business models. Now more than ever, the timeless wisdom of Douglas McGregor can light the path towards a management style that nurtures leadership capability, creates effective teams, ensures internal alignment, achieves high performance, and cultivates an authentic, value-driven workplace--lessons we all need to learn as we make our way in this brave new world of the 21st century.