Nucleic acid testing (NAT) of organ donors: is the 'best' test the right test? A consensus conference report

Nucleic acid testing (NAT) for HIV, HBV and HCV shortens the time between infection and detection by available testing. A group of experts was selected to develop recommendations for the use of NAT in the HIV/HBV/HCV screening of potential organ donors. The rapid turnaround times needed for donor testing and the risk of death while awaiting transplantation make organ donor screening different from screening blood-or tissue donors. In donors with no identified risk factors, there is insufficient evidence to recommend routine NAT, as the benefits of NAT may not outweigh the disadvantages of NAT especially when false-positive results can lead to loss of donor organs. For donors with identified behavioral risk factors, NAT should be considered to reduce the risk of transmission and increase organ utilization. Informed consent balancing the risks of donor-derived infection against the risk of remaining on the waiting list should be obtained at the time of candidate listing and again at the time of organ offer. In conclusion, there is insufficient evidence to recommend universal prospective screening of organ donors for HIV, HCV and HBV using current NAT platforms. Further study of viral screening modalities may reduce disease transmission risk without excessive donor loss.

The role of Fyn kinase in the release from metaphase in mammalian oocytes

Meiosis in mammalian oocytes starts during embryonic life and arrests for the first time before birth, at prophase of the first meiotic division. The second meiotic arrest occurs after spindle formation at metaphase of the second meiotic division (MII) in selected oocytes designated for ovulation. The fertilizing spermatozoon induces the release from MII arrest only after the oocyte's spindle assembly checkpoint (SAC) was deactivated. Src family kinases (SFKs) are nine non-receptor protein tyrosine kinases that regulate many key cellular functions. Fyn is an SFK expressed in many cell types, including oocytes. Recent studies, including ours, imply a role for Fyn in exit from meiotic and mitotic metaphases. Other studies demonstrate that SFKs, particularly Fyn, are required for regulation of microtubules polymerization and spindle stabilization. Altogether, Fyn is suggested to play an essential role in signaling events that implicate SAC pathway and hence in regulating the exit from metaphase in oocytes and zygote.

The coagulant response in sepsis and inflammation

Critically ill patients often have systemic activation of both inflammation and coagulation. Increasing evidence points to an extensive cross-talk between these two systems, whereby inflammation not only leads to activation of coagulation, but coagulation also considerably affects inflammatory activity. The intricate relationship between inflammation and coagulation may have major consequences for the pathogenesis of microvascular failure and subsequent multiple organ failure, as a result of severe infection and the associated systemic inflammatory response. Molecular pathways that contribute to inflammation-induced activation of coagulation have been precisely identified. Activation of the coagulation system and ensuing thrombin generation is dependent on an interleukin-6-induced expression of tissue factor on activated mononuclear cells and endothelial cells and is insufficiently counteracted by tissue factor pathway inhibitor. Simultaneously, endothelial-bound anticoagulant mechanisms, in particular the protein C system and the antithrombin system, are shut-off by pro-inflammatory cytokines. Modulation of inflammatory activity by activation of coagulation also occurs by various mechanisms. Activated coagulation proteases, such as the tissue factor-factor VIIa complex, factor Xa and thrombin can bind to protease-activated receptors on various cells and the ensuing intracellular signaling leads to increased production of pro-inflammatory cytokines and chemokines. Physiological anticoagulants can modulate inflammatory activity as well. Increasing knowledge on the various mechanisms underlying activation of inflammation and coagulation may lead to better (adjunctive) management strategies in critically ill patients.

Epidemiology and management of bleeding in patients using vitamin K antagonists

Vitamin K antagonists are effective in the prevention and treatment of a variety of arterial and venous thrombotic disorders, but are associated with an increased risk of serious bleeding complications. According to well documented studies of patients using vitamin K antagonists, the incidence of major bleeding is 0.5% per year and the incidence of intracranial bleeding is 0.2% per year, however, in real life practice this incidence may be even higher. Risk factors for bleeding are the intensity of anticoagulation, the management strategy to keep the INR in the desired range, and patient characteristics. In case of serious bleeding complications in a patient who uses vitamin K antagonists, this anticoagulant treatment can be quickly reversed by administration of vitamin K or coagulation factor concentrates.

Design, fabrication, and characterization of a composite scaffold for bone tissue engineering

Poly(lactide-co-glycolide) (PLGA) scaffolds have been successfully used in bone tissue engineering, with or without hydroxyapatite (HA) and with a macroporosity given either by simple PLGA sphere packaging and/or by leaching out NaCl. The objective of this work was the optimization of the design parameters for bone tissue engineering scaffolds made by sintering microspheres of PLGA, HA nanocrystals for matrix reinforcement and osteoconduction, and salt crystals for macroporosity and control of matrix pore size. Microsphere fabrication by a single-emulsion and solvent evaporation technique was first optimized to obtain a high yield of PLGA microspheres with a diameter between 80 and 300 microm. The influence of the sintering process and matrix composition on the scaffold structure was then evaluated morphologically and mechanically. Three scaffold types were tested for biocompatibility by culturing with human fibroblasts for up to 14 days. The most important parameters to obtain microspheres with the selected diameter range were the viscosity ratio of the dispersed phase to the continuous phase and the relative volume fraction of the 2 phases. The Young's modulus and the ultimate strength of the sintered matrices ranged between 168-265 MPa and 6-17 MPa, respectively, within the range for trabecular bone. Biocompatibility was demonstrated by fibroblast adhesion, proliferation, and spreading throughout the matrix. This work builds upon previous work of the PLGA/HA sintering technique to give design criteria for fabricating a bone tissue engineered matrix with optimized morphological, functional, and biological properties to fit the requirements of bone replacements.

Use of recombinant factor VIIa in the perioperative period

Recombinant activated factor VII (rFVIIa) is a pro-haemostatic agent that can be used for patients with haemophilia and inhibiting antibodies towards a coagulation factor. Recombinant factor VIIa is, however, increasingly used for several other indications, including patients who experience serious and life-threatening bleeding. In addition, rFVIIa has been evaluated for the prevention of major blood loss in patients undergoing surgical procedures that are known to be associated with major blood loss. In this manuscript we review the data on efficacy and safety of rFVIIa in the prevention of excessive blood loss and transfusion requirements in the perioperative period. We conclude that recombinant factor VIIa is a promising agent for perioperative prevention of major blood loss but that its efficacy will probably vary between specific clinical settings. Its exact place in surgery warrants further clinical trials in various situations that will also more precisely determine the safety of this intervention.

Ventilator-induced coagulopathy in experimental Streptococcus pneumoniae pneumonia

Pneumonia, the main cause of acute lung injury, is characterised by a local pro-inflammatory response and coagulopathy. Mechanical ventilation (MV) is often required. However, MV can lead to additional injury: so-called ventilator-induced lung injury (VILI). Therefore, the current authors investigated the effect of VILI on alveolar fibrin turnover in Streptococcus pneumoniae pneumonia. Pneumonia was induced in rats, followed 48 h later by either lung-protective MV (lower tidal volumes (LV(T)) and positive end-expiratory pressure (PEEP)) or MV causing VILI (high tidal volumes (HV(T)) and zero end-expiratory pressure (ZEEP)) for 3 h. Nonventilated pneumonia rats and healthy rats served as controls. Thrombin-antithrombin complexes (TATc), as a measure for coagulation, and plasminogen activator activity, as a measure of fibrinolysis, were determined in bronchoalveolar lavage fluid (BALF) and serum. Pneumonia was characterised by local (BALF) activation of coagulation, resulting in elevated TATc levels and attenuation of fibrinolysis compared with healthy controls. LV(T)-PEEP did not influence alveolar coagulation or fibrinolysis. HV(T)-ZEEP did intensify the local procoagulant response: TATc levels rose significantly and levels of the main inhibitor of fibrinolysis, plasminogen activator inhibitor-1, increased significantly. HV(T)-ZEEP also resulted in systemic elevation of TATc compared with LV(T)-PEEP. Mechanical ventilation causing ventilator-induced lung injury increases pulmonary coagulopathy in an animal model of Streptococcus pneumoniae pneumonia and results in systemic coagulopathy.

Catastrophic antiphospholipid syndrome mimicking a malignant pancreatic tumour – a case report

Abstract

The catastrophic antiphospholipid syndrome is characterised by rapid onset thromboses, often resistant to conventional anticoagulant treatment, and resulting in life threatening multiple organ dysfunction. The diagnosis of catastrophic antiphospholipid syndrome may be difficult, predominantly due to its frequently atypical presentation. We report a case of a 35-year-old female who presented with a pancreatic tumour and extensive thromboses. Following a storm of ischemic events due to thrombotic occlusions in spite of therapeutic heparin dose, the suspicion of catastrophic antiphospholipid syndrome emerged. The patient was successfully treated with anticoagulants, immunuglobulins, plasmapheresis and rituximab. The present report shows that the use of the diluted Russell’s viper venom time can be helpful in providing additional information on the lupus anticoagulans antibody status, allowing careful monitoring of lupus anticoagulans conversion and hence response to therapy.

Absence of Pneumocystis jiroveci pneumonia in liver transplantation recipients receiving short-term (3-month) prophylaxis

Pneumocystis jiroveci (formerly known as Pneumocystis carinii) is a fungal pathogen that causes pneumonia (PCP) in liver transplant recipients. Consequently, prophylaxis with trimethoprim-sulfamethoxazole (TMP/SMZ) is typically administered for at least 1 year at most liver transplant programs. At our center we have utilized a short-term (3-month) prophylactic regimen with TMP/SMZ for the past decade and report our experience and speculate on the potential widespread application of this approach.

METHODS

For patients transplanted at our center between January 1997 and January 2007, we recorded all documented PCP infections by review of our liver transplant database and hospital-based electronic medical records system, both of which record all infections and culture results.

RESULTS

We recorded no cases of PCP in any of the liver transplant recipients at our center during the study period.

CONCLUSIONS

We report the absence of PCP in a large cohort of liver transplant recipients receiving a short-term (3-month) prophylaxis with TMP/SMZ. These findings provide a rational basis to consider short-term (3-month) PCP prophylaxis or avoidance of prophylaxis altogether in selected low-risk patients.