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Biomedical subjects

Lawrence D Petz

Publications and source records attributed to Lawrence D Petz.

10 recordsLinked to original sources
PubMed2006

Photochemically treated fresh frozen plasma for transfusion of patients with acquired coagulopathy of liver disease.

An ex vivo photochemical treatment (PCT) process was developed to inactivate pathogens in fresh frozen plasma (PCT-FFP). A prospective, controlled, double-blinded, randomized study was conducted to evaluate the efficacy and safety of PCT-FFP compared with conventional FFP (C-FFP). Patients (n = 121) with acquired coagulopathy, largely due to liver disease, including hepatic transplantation, were transfused with either PCT-FFP or C-FFP for up to 7 days. Primary end points were changes in the prothrombin time (PT) and the partial thromboplastin time (PTT) in response to the first FFP transfusion. Secondary analyses compared changes in the PT and the PTT, factor VII levels, clinical hemostasis, blood component usage, and safety following FFP transfusions for up to 7 days. Following the first transfusion, correction in the PT and PTT adjusted for FFP dose and patient weight was not different. Changes in the PT were equivalent between treatment groups (P = .002 by noninferiority). Equivalence was not demonstrated for changes in the PTT. Following multiple transfusions, correction of the PT and the PTT was similar between groups. No differences were observed in use of blood components, clinical hemostasis, or safety. These results suggest PCT-FFP supported hemostasis in the treatment of acquired coagulopathy similarly to conventional FFP.

Aged↗
PubMed2006

Bystander immune cytolysis.

In addition to alloimmune and autoimmune cell lysis, a third category of immune destruction of blood cells should be recognized. This additional immunologic response occurs when cells or tissues are injured by immunologic reactions in which the cells act as "innocent bystanders." One mechanism by which an immune response to an exogenous antigen leads to the destruction of autologous blood cells is the temporary development of autoantibodies. This is actually an alloimmune reaction which results in a temporary state of "pseudo"-autoimmunity. Although originally described as a type of hemolysis of autologous cells, the concept of bystander immune cytolysis has been extended to include other instances in which immune destruction of cells is caused by antibody that is not developed in response to intrinsic antigens on the cell being lysed. In recent years, compelling data have been presented documenting bystander immune cytolysis in a number of different clinical settings, and efforts have been made to define the mechanisms by which this occurs. Physicians must be aware that some examples of immune lysis of autologous cells are, in reality, examples of temporary bystander immune cytolysis rather than true autoimmune disease. Furthermore, some alloimmune hemolytic reactions can result in lysis of bystander cells.

Anemia, Sickle Cell↗
PubMed2005

Immune hemolysis associated with transplantation.

Immune hemolysis is one of the adverse effects that can occur following hematopoietic cell or solid organ transplantation. Understanding the clinical settings and the various causes of immune hemolysis is necessary for prompt diagnosis and appropriate management. One of the important causes is the passenger lymphocyte syndrome, which occurs following minor ABO blood group incompatibility between donor and recipient. Hemolysis in this syndrome is often modest in severity but may be severe and even life-threatening. Major ABO blood group incompatibility is also associated with hemolysis, although this is relatively unusual and generally not severe. Autoimmune hemolytic anemia is a relatively common late complication of allogeneic transplantation and carries significant risk of mortality. Also, alloantibodies may be produced by engrafted cells of the donor's immune system or by residual cells of the patient's immune system following hematopoietic cell transplantation. Hemolysis may occur after solid organ transplantation, particularly as part of the passenger lymphocyte syndrome.

ABO Blood-Group System↗
PubMed2004

A physician's guide to transfusion in autoimmune haemolytic anaemia.

Patients with autoimmune haemolytic anaemia (AIHA) frequently have anaemia of sufficient severity as to require a blood transfusion. However, it is impossible to find compatible blood when, as is frequently the case, the autoantibody in the patient's serum reacts with all normal red blood cells. Further, the autoantibody may mask the presence of a red cell alloantibody capable of causing a haemolytic transfusion reaction. Optimal patient management in this clinical setting requires special compatibility test procedures in the transfusion service laboratory. Equally important is that clinicians must understand the principles of the compatibility tests performed. Provided appropriate compatibility tests are performed, the indications for transfusion in patients with AIHA are not significantly different than for similarly anaemic patients without AIHA. Communication between clinicians and laboratory personnel are important to review the urgency of transfusion and the compatibility test methods used to select the optimal unit of red blood cells for transfusion.

Anemia, Hemolytic, Autoimmune↗
PubMed2002

Red cell antigens as functional molecules and obstacles to transfusion.

Blood group antigens (BGAs) can act as functional molecules but also can evoke autoantibodies and alloantibodies, causing autoimmune hemolytic anemia, hemolytic disease of the newborn and hemolytic transfusion reactions. In Section I, Dr. Marilyn Telen discusses physiologic and pathologic functions of RBC BGA-bearing molecules. She reviews some associations of BGAs with RBC membrane integrity and hemolytic anemia; association of BGAs with enzymatic and transport functions; and adhesion molecules expressed by RBCs, especially with reference to their pathophysiological role in sickle cell disease. In Section II, Dr. Lawrence Petz discusses the problems of providing blood for patients who have RBC autoantibodies. He provides an algorithm for excluding the presence of "hidden" alloantibodies, when all units appear to be incompatible due to the autoantibody. He emphasizes that clinicians should be aware of these approaches and not accept "the least incompatible unit." In Section III, Dr. George Garratty describes two processes, in development, that produce RBCs that result in RBCs that can be described as "universal" donor or "stealth" RBCs. The first process involves changing group A, B, or AB RBCs into group O RBCs by removing the immunospecific sugars responsible for A and B specificity by using specific enzymes. The second process involves covering all BGAs on the RBC surface using polyethylene glycol (PEG). Results of in vitro and in vivo studies on these modified RBCs are discussed.

Anemia, Hemolytic, Autoimmune↗