Bradykinin metabolism and hypotensive transfusion reactions

Comparison of cell salvage with one and two suction devices during cesarean section in patients with placenta previa and/or accrete: a randomized controlled trial

Background

Cell salvage has recently been recommended for obstetric use in cases with a high risk of massive hemorrhage during cesarean section (CS). However, limited data are available to support the use of one suction device to collect lost blood. This study aimed to investigate the volume of red blood cells (RBCs) salvaged and the components of amniotic fluid (AF) in blood salvaged by one suction device or two devices during CS in patients with placenta previa and/or accrete.

Methods

Thirty patients with placenta previa and/or accrete undergoing elective CS in the Women's Hospital of Zhejiang University School of Medicine were recruited for the present study from November 1, 2017 to December 1, 2018. The patients were randomly assigned to one of the two groups according to an Excel-generated random number sheet: Group 1 (n = 15), in which only one suction device was used to aspirate all blood and AF, and Group 2 (n = 15), in which a second suction device was mainly used to aspirate AF before the delivery of the placenta. Three samples of blood per patient (pre-wash, post-wash, and post-filtration) were collected to measure AF components. The salvaged RBC volumes were recorded. Continuous data of pre-wash, post-wash, and post-filtration samples were analyzed by using one-way analysis of variance with Tukey's test for multiple comparisons, or Kruskal-Wallis test with Dunn test for multiple comparisons. Comparisons of continuous data between Group 1 and Group 2 were conducted using Student's t test or Mann-Whitney U test.

Results

The salvaged RBC volume was significantly higher in Group 1 than that in Group 2 (401.6 ± 77.2 mL vs. 330.1 ± 53.3 mL, t = 4.175, P < 0.001). In both groups, squamous cells, lamellar bodies, and fat were significantly reduced by washing (all P<0.001) and squamous cells were further reduced by filtering (P < 0.001). Squamous cells were found in six post-filtration samples (three from each group). Lamellar bodies and fat were completely removed by filtering. Insulin-like growth factor binding protein 1, alpha-fetoprotein, albumin, lactate dehydrogenase, and potassium were significantly reduced post-wash (all P < 0.05), with no further significant reduction after filtration in either group (all P > 0.05). The mean percentage of fetal RBCs post-filtration was (1.8 ± 0.8)% with a range of 1.0% to 3.5% and (1.9 ± 0.9)% with a range of 0.7% to 4.0% in Groups 1 and 2, respectively, showing no significant difference between the two groups (U = 188.5, P = 0.651).

Conclusion

Cell salvage performed by one suction device could result in higher volume of salvaged RBCs and can be used safely for CS in patients with placenta previa and/or accrete when massive hemorrhage occurs.

Trial registration number

ChiCTR-INR-17012926, http://www.chictr.org.cn/ Chinese Clinical Trial Registry.

Leukocytapheresis for patients with acute myeloid leukemia presenting with hyperleukocytosis and leukostasis: a contemporary appraisal of outcomes and benefits

Introduction: Hyperleukocytosis, defined as a total white blood cell count (WBC) >50 or more commonly >100 × 10⁹ cells/L, is a presenting feature of acute myeloid leukemia (AML) in about 6-20% of cases and is associated with a higher risk of tumor lysis syndrome (TLS), disseminated intravascular coagulation (DIC), clinical leukostasis with end organ damage, and mortality.Areas covered: In this review, authors discuss the implications of hyperleukocytosis in AML and the current understanding of cytoreductive strategies with a focus on the use of leukocytapheresis.Expert commentary: Efforts to rapidly reduce peripheral myeloblasts have included the use of leukocytapheresis. Early studies demonstrated feasibility in reducing peripheral WBC and blast counts as well as clinically relevant patient outcomes which prompted its common use for many years. However, more recent data have directly challenged the previously touted reports of reduced TLS and DIC incidence as well as survival benefit, even in patients with clinical leukostasis. The use of leukocytapheresis remains highly controversial with wide practice variations among physicians, institutions, and countries given the lack of high-quality data, risks associated with leukocytapheresis itself, associated high costs, resource utilization, and lack of evidence-based clinical guidelines.

Profound Intraoperative Hypotension Associated With Transfusion via the Belmont Fluid Management System

This retrospective observational case series conducted at 2 large academic centers over a 4-year period consists of 15 cases of profound hypotension in surgical patients immediately after initiation of the Belmont Fluid Management System for rapid transfusion of blood products. Halting the infusion and administering vasoactive agents led to resolution of hypotension. Repeat transfusion with the Belmont system resulted in repeat hypotension unless counteracted with vasopressors. No etiology was elucidated. This represents the largest documented association of acute hypotensive transfusion reaction with any rapid infusion system in surgical patients.

Cryoglobulinemia as a Possible Primer for TRALI: Report of a Case

Waldenström macroglobulinemia (WM) is a form of lymphoplasmacytic lymphoma that can cause hyperviscosity syndrome due to unchecked monoclonal antibody production. Some patients are also found to have associated cryoglobulinemia, which can cause systemic complications including vasculitis, renal disease, and pulmonary complications. Cryoglobulins can also serve as a source of interference with various laboratory assays. Therapeutic plasma exchange (TPE) is one of the recommended treatment modalities to manage hyperviscosity. Herein, we present the case of an 84-year-old female patient with Waldenström macroglobulinemia who presented with hyperviscosity syndrome and discrepant laboratory findings, and who then developed transfusion-related acute lung injury (TRALI) during TPE. This case is one of many in the emerging possible linkages observed between cryoglobulinemia and TRALI.

Transfusion-associated hazards: A revisit of their presentation

As a therapy or a support to other therapies, despite being largely beneficial to patients in general, transfusion it is not devoid of some risks. In a moderate number of cases, patients may manifest adverse reactions, otherwise referred to as transfusion-associated hazards (TAHs). The latest French 2016 haemovigilance report indicates that 93% of TAHs are minor (grade 1), 5.5% are moderate (grade 2) and 1.6% are severe (grade 3), with only five deaths (grade 4) being attributed to transfusion with relative certainty (imputability of level [or grade] 1 to 3). Health-care providers need to be well aware of the benefits and potential risks (to best evaluate and discuss the benefit-risk ratio), how to prevent TAHs, the overall costs and the availability of alternative therapeutic options. In high-income countries, most blood establishments (BEs) and hospital blood banks (HBBs) have developed tools for reporting and analysing at least severe transfusion reactions. With nearly two decades of haemovigilance, transfusion reaction databases should be quite informative, though there are four main caveats that prevent it from being fully efficient: (ai) reporting is mainly declarative and is thus barely exhaustive even in countries where it is mandatory by law; (aii) it is often difficult to differentiate between the different complications related to transfusion, diseases, comorbidities and other types of therapies in patients suffering from debilitating conditions; (aiii) there is a lack of consistency in the definitions used to describe and report some transfusion reactions, their severity and their likelihood of being related to transfusion; and (aiv) it is difficult to assess the imputability of a particular BC given to a patient who has previously received many BCs over a relatively short period of time. When compiling all available information published so far, it appears that TAHs can be analysed using different approaches: (bi) their pathophysiological nature; (bii) their severity; (biii) the onset scheme; (biv) a quality assessment (preventable or non-preventable); (bv) their impact on ongoing therapy. Moreover, TAHs can be reported either in a non-integrative or in an integrative way; in the latter case, presentation may also differ when issued by a blood establishment or a treating ward. At some point, a recapitulative document would be useful to gain a better understanding of TAHs in order to decrease their occurrence and severity and allow decision makers to determine action plans: this is what this review attempts to make. This review attempts to merge the different aspects, with a focus on the hospital side, i.e., how the most frequent TAHs can be avoided or mitigated.

Transfusion reactions: prevention, diagnosis, and treatment

Blood transfusion is one of the most common procedures in patients in hospital so it is imperative that clinicians are knowledgeable about appropriate blood product administration, as well as the signs, symptoms, and management of transfusion reactions. In this Review, we, an international panel, provide a synopsis of the pathophysiology, treatment, and management of each diagnostic category of transfusion reaction using evidence-based recommendations whenever available.

Incidence of hypotension and acute hypotensive transfusion reactions following platelet concentrate transfusions

BACKGROUND AND OBJECTIVES

Platelet concentrates (PCs) are associated with transfusion reactions involving hypotension, particularly bradykinin-mediated acute hypotensive transfusion reactions. This study aims to determine the incidence of hypotensive events and more specifically acute hypotensive transfusion reaction associated with PC transfusions. We also sought to ascertain whether these reactions are associated with elevated bradykinin levels.

MATERIALS AND METHODS

This is a prospective descriptive study of PCs administered at Sainte-Justine Hospital over 28 months. All PCs administered during this period were screened for hypotension through review of all transfusion-associated reaction reports (TARRs) sent to the blood bank. All residual PC bags were returned to the blood bank. TARRs associated with hypotension were reviewed by adjudicators that established the imputability of the PC transfusion to the reaction. Bradykinin levels were sampled in the first 168 PC bags returned to the blood bank. Levels were compared between PCs associated with hypotension and control PCs not associated with hypotension.

RESULTS

A total of 3672 PC bags were returned to the blood bank; 25 PCs were associated with hypotension. Adjudicators ascertained that five hypotensive events were imputable to PCs of which one was an acute hypotensive transfusion reaction (incidence: 0·03%). Bradykinin level in the latter PC was 10 pg/ml, whereas levels were 226·2 ± 1252 pg/ml in the 143 control PCs.

CONCLUSION

Our results show a low incidence of hypotension after PC transfusion. We identified only one acute hypotensive transfusion reaction. No correlation between bradykinin level and the occurrence of acute hypotensive reactions could be observed given that only one event was identified.

Washed RBCs prevent recurrent acute hypotensive transfusion reactions

OBJECTIVES

To examine whether a liver transplant patient, who was not taking an angiotensin-converting enzyme inhibitor and developed two episodes of hypotension with systolic pressure in the 50s within minutes of starting an RBC transfusion, may have had a disturbance in the production and metabolism of bradykinin and des-Arg(9)-BK.

METHODS

All patient information was obtained by reviewing the electronic medical record, the transfusion service database, and transfusion reaction investigation records.

RESULTS

The blood pressure returned to normal once the transfusions were discontinued. In an effort to mitigate the acute hypotension, the blood products were washed. Subsequently, the patient received three additional packed RBC transfusions without further incidents of hypotension.

CONCLUSIONS

Our experience suggests that washing the products was an acceptable and effective preventative measure to avoid further acute hypotensive transfusion reactions in patients unable to metabolize these vasodilators present in the donor units.

Bradykinin inhibits oxidative stress-induced cardiomyocytes senescence via regulating redox state

Background

Cell senescence is central to a large body of age related pathology, and accordingly, cardiomyocytes senescence is involved in many age related cardiovascular diseases. In consideration of that, delaying cardiomyocytes senescence is of great importance to control clinical cardiovascular diseases. Previous study indicated that bradykinin (BK) protected endothelial cells from senescence induced by oxidative stress. However, the effects of bradykinin on cardiomyocytes senescence remain to be elucidated. In this study, we investigated the effect of bradykinin on H₂O₂-induced H9C2 cells senescence.

Methods and Results

Bradykinin pretreatment decreased the senescence induced by H₂O₂ in cultured H9C2 cells in a dose dependent manner. Interestingly, 1 nmol/L of BK almost completely inhibited the increase in senescent cell number and p21 expression induced by H₂O₂. Since H₂O₂ induces senescence through superoxide-induced DNA damage, we also observed the DNA damage by comet assay, and BK markedly reduced DNA damage induced by H₂O₂, and moreover, BK treatment significantly prevented reactive oxygen species (ROS) production in H9C2 cells treated with H₂O₂. Importantly, when co-incubated with bradykinin B2 receptor antagonist HOE-140 or eNOS inhibitor N-methyl-L-arginine acetate salt (L-NAME), the protective effects of bradykinin on H9C2 senescence were totally blocked. Furthermore, BK administration significantly prevented the increase in nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity characterized by increased ROS generation and gp91 expression and increased translocation of p47 and p67 to the membrane and the decrease in superoxide dismutase (SOD) activity and expression induced by H₂O₂ in H9C2 cells, which was dependent on BK B2 receptor mediated nitric oxide (NO) release.

Conclusions

Bradykinin, acting through BK B2 receptor induced NO release, upregulated antioxidant Cu/Zn-SOD and Mn-SOD activity and expression while downregulating NADPH oxidase activity and subsequently inhibited ROS production, and finally protected against cardiomyocytes senescence induced by oxidative stress.

Acute hypotension associated with intraoperative cell salvage using a leukocyte depletion filter during management of obstetric hemorrhage due to amniotic fluid embolism

Amniotic fluid embolism (AFE) is a rare but catastrophic obstetric complication that can lead to profound coagulopathy and hemorrhage. The role of cell salvage and recombinant human Factor VIIa (rFVIIa) administration in such cases remains unclear. We present a case of AFE and describe our experience with the use of cell salvage and rFVIIa administration during the resuscitation. Cell salvage and transfusion through a leukocyte depletion filter was attempted after the diagnosis of AFE was made, but the attempted transfusion was immediately followed by hypotension and a worsening of hemodynamics. rFVIIa, on the contrary, was used with clinical improvement in coagulopathy and without apparent adverse thrombotic effect.

The development of a novel molecular assay examining the role of aminopeptidase P polymorphisms in acute hypotensive transfusion reactions

CONTEXT

Acute hypotensive transfusion reactions are potentially harmful adverse effects of transfusion attributable to bradykinin generation. They are most often seen in patients taking angiotensin-converting enzyme (ACE) inhibitors (ACE-Is) because of the role ACE plays in metabolizing bradykinin. However, a number of acute hypotensive transfusion reactions occur in patients not taking ACE-Is. Aminopeptidase P (APP), another important enzyme responsible for bradykinin degradation, is encoded by the polymorphic XPNPEP2 gene. Some polymorphisms in XPNPEP2 have been associated with decreased APP activity. However, the role that APP polymorphisms play in acute hypotensive transfusion reactions has never been investigated.

OBJECTIVE

To develop a molecular assay to examine for the C-2399A single-nucleotide polymorphism (SNP) in the APP gene, XPNPEP2, in patients experiencing acute hypotensive transfusion reactions unassociated with ACE-Is.

DESIGN

We developed an assay using polymerase chain reaction and DNA sequencing with primers targeted at XPNPEP2 (5'-GAGTATTATGTGGGGACCATCC-3' and 5'-ATGCCTCGCAGAGACAAGAG-3'). Polymorphism zygosity was determined by comparing the sense/antisense sequencing results. This assay was then applied to patients with acute hypotensive transfusion reactions not taking ACE-Is (n  =  4).

RESULTS

A C-2399A SNP assay was successfully developed and applied to patients with acute hypotensive transfusion reactions. In a pilot study, 2 patients (50%) were found to possess C-2399A polymorphisms. One was found to be homozygous, and the other was heterozygous.

CONCLUSIONS

Our C-2399A SNP assay can be used to study acute hypotensive transfusion reactions in patients not taking ACE-Is. Initial data indicate that the C-2399A polymorphism may be a contributing factor in such reactions. However, further studies are necessary to better define the role of APP polymorphisms in relation to acute hypotensive transfusion reactions unassociated with ACE-Is.

Effects of a novel bradykinin B1 receptor antagonist and angiotensin II receptor blockade on experimental myocardial infarction in rats

Background

The aim of the present study was to evaluate the cardiovascular effects of the novel bradykinin B1 receptor antagonist BI-113823 following myocardial infarction (MI) and to determine whether B1 receptor blockade alters the cardiovascular effects of an angiotensin II type 1 (AT1) receptor antagonist after MI in rats.

Methodology/Principal Findings

Sprague Dawley rats were subjected to permanent occlusion of the left descending coronary artery. Cardiovascular function was determined at 7 days post MI. Treatment with either B1 receptor antagonist (BI-113823) or AT1 receptor antagonist (irbesartan) alone or in combination improved post-MI cardiac function as evidenced by attenuation of elevated left ventricular end diastolic pressure (LVEDP); greater first derivative of left ventricular pressure (± dp/dt max), left ventricle ejection fraction, fractional shorting, and better wall motion; as we as reductions in post-MI up-regulation of matrix metalloproteinases 2 (MMP-2) and collagen III. In addition, the cardiac up-regulation of B1 receptor and AT1 receptor mRNA were markedly reduced in animals treated with BI 113823, although bradykinin B2 receptor and angiotensin 1 converting enzyme (ACE1) mRNA expression were not significantly affected by B1 receptor blockade.

Conclusions/Significance

The present study demonstrates that treatment with the novel B1 receptor antagonist, BI-113823 improves post-MI cardiac function and does not influence the cardiovascular effects of AT1 receptor antagonist following MI.

Reducing noninfectious risks of blood transfusion

As screening for transfusion-associated infections has improved, noninfectious complications of transfusion now cause the majority of morbidity and mortality associated with transfusion in the United States. For example, transfusion-related acute lung injury, transfusion-associated circulatory overload, and hemolytic transfusion-reactions are the first, second, and third leading causes of death from transfusion, respectively. These complications and others are reviewed, and several controversial methods for prevention of noninfectious complications of transfusion are discussed, including universal leukoreduction of erythrocyte units, use of male-only plasma, and restriction of erythrocyte storage age.

Factor XII mutations, estrogen-dependent inherited angioedema, and related conditions

The clinical, biochemical and genetic features of the conditions known as estrogen-dependent inherited angioedema, estrogen-associated angioedema, hereditary angioedema with normal C-1 inhibitor, type III angioedema, or factor XII angioedema are reviewed. Discussion emphasizes pathogenesis, diagnosis, and management.

Heparin-induced anaphylactic and anaphylactoid reactions: two distinct but overlapping syndromes

BACKGROUND

Heparin-induced anaphylactic and anaphylactoid reactions are of increasing clinical and scientific interest, particularly given the recent identification of a syndrome of heparin-induced anaphylaxis due to oversulfated chondroitin sulfate (OSCS), a contaminant in certain heparin preparations. However, heparin-induced anaphylactoid reactions also have been reported to be a consequence of immune-mediated heparin-induced thrombocytopenia (HIT).

OBJECTIVE

To summarize the clinical features and pathophysiology of two distinct disorders, HIT-associated anaphylactoid reactions as well as anaphylaxis resulting from OSCS-contaminated heparin.

METHODS

We review literature describing these two types of heparin-induced anaphylactic and anaphylactoid reactions, and seek potential pathophysiologic links between them.

RESULTS

Intravenous bolus heparin administered to patients with circulating 'HIT antibodies', usually as a result of recent heparin therapy, can produce anaphylactoid reactions, probably as a consequence of in vivo activation of platelets and, possibly, leukocytes. Affected patients often evince fever/chills, hypertension and/or acute respiratory compromise ('pseudo-pulmonary embolism'). In contrast, heparin-induced anaphylaxis is caused by activation of the contact system, with formation of vasoactive kinins (bradykinin, des-arg(9)-bradykinin). This latter syndrome has been linked in an epidemic form to administration of OSCS-contaminated heparin; these reactions feature prominent hypotension and laryngeal edema. Hemodialysis patients are at increased risk for both syndromes. There is evidence that OSCS-contaminated heparin itself increases the risk of HIT compared with non-contaminated heparin.

CONCLUSION

Two distinct syndromes of heparin-induced anaphylaxis and anaphylactoid reactions exist. These seem to share certain epidemiologic features, given that OSCS-contaminated heparin can produce anaphylaxis through contact system activation but also could increase risk of HIT and HIT-associated anaphylactoid reactions.

[Hypotension and adverse transfusion reactions: from the associated clinical signs to the hypotensive transfusion reaction]

OBJECTIVE

The first aim of this study was to confirm the presence of hypotension blood transfusion reactions and to assess the part of hypotension as a principal event, as defined by the literature but not characterized in French haemovigilance data. As well, recent series of several cases led us to consider a possible incidence increase.

STUDY DESIGN

Using a retrospective observation, the haemovigilance data from 2000 to the end of 2007 of two French regions were reviewed. During this period, 1159657 blood units were transfused by nearly 100 hospitals and 3727 adverse reactions observed.

RESULTS

One hundred and sixty-eight adverse reactions with hypotension were noticed and analyzed, representing 4.5% of all transfusion reactions and revealing an incidence of 14.5 for 100000 blood units transfused. It turned out to be mostly male recipients, severe reactions and appearing rather in the beginning of transfusions. Although platelets having greater incidence, all types of blood products may be involved. The clinical diagnosis was the following: 40 to 47% were classified as febrile reactions, 13 to 17% were allergic reactions, 8 to 9% were due to immunologic and/or haemolytic reactions, 5 to 7% resulted of cardiologic disorders, 5% resulted of hypovolemic contexts and 22% were unexplained hypotensive transfusion reactions.

CONCLUSION

In about three cases out of four, transfusion-induced hypotension was associated with other clinical reactions. Indeed, hypotensive transfusion reactions were identified, having an incidence of 3.2 for 100000 blood units transfused. Furthermore, there was no explanation found for the incidence increase in our region during 2007. A national study was suggested to analyse the national data as well as a prospective study to clear out this type of transfusion reactions.

Acute hypotensive transfusion reaction during liver transplantation in a patient on angiotensin converting enzyme inhibitors from low aminopeptidase P activity

Acute hypotensive transfusion reactions are newly characterized transfusion reactions in which hypotension is the prominent feature. The pathophysiology of acute hypotensive transfusion reactions is related to the bradykinin function and its metabolism. A liver transplant recipient on treatment with an angiotensin converting enzyme inhibitor developed sudden hypotension, that is, systolic pressure of 60 mm Hg, after receiving 200 mL of a blood product mixture without significant surgical blood loss. He responded to the resuscitation measure, although hypotension developed again after a challenge transfusion of 200 mL of the blood mixture. A severe hypotensive reaction to the blood transfusion and diffuse bleeding from the dissection surfaces forced the transplantation to be aborted after the common bile duct had been divided. We hypothesized that the patient had an acute hypotensive transfusion reaction due to disordered bradykinin metabolism. Analysis of his blood showed low levels of both angiotensin converting enzyme and aminopeptidase P enzyme activity, confirming that the patient experienced an acute hypotensive transfusion reaction that was due to the use of the angiotensin converting enzyme inhibitor and was precipitated by an abnormality in the metabolic enzyme pathway. It is recommended to discontinue angiotensin converting enzyme inhibitors and switch to a different class of antihypertensive medications for patients with a high Model for End-Stage Liver Disease score on the waiting list for liver transplantation.

Generation of kinins during preparation and storage of whole blood?derived platelet concentrates

BACKGROUND

Leukoreduction of platelet (PLT) concentrates (PCs) may be associated with hypotension in recipients, and a role for bradykinin (BK)-related peptides has been proposed for this side effect.

STUDY DESIGN AND METHODS

The concentration of BK and one of its vasoactive metabolites, des-arginine(9)-BK (des-Arg(9)-BK), was measured in a large number of PCs as a function of leukoreduction and storage duration with specific enzyme immunoassays and complementary techniques.

RESULTS

On Day 0 of storage, kinins were detected in leukoreduced and unfiltered PCs at a concentration lower than 100 pg per mL. During storage, both kinin levels peaked on Day 5 of storage, with a concentration higher than 1 ng per mL in 22 percent of PCs whether filtered on Day 0 or not. Physicochemical and pharmacologic characterizations of immunoreactive kinins confirm their nature. In vitro activation of the contact system of the corresponding PLT-poor plasma showed that a high kinin concentration on Day 5 of the storage corresponded with a low kinin-forming capacity of plasma. On Day 7, BK was no longer elevated presumably due to its degradation and the depletion of kinin-forming capacity of the plasma in stored PCs. The activities of metallopeptidases that metabolize BK-related peptides in plasma from PCs were at levels similar to those recorded in the plasma of a normal reference population and were unaffected by storage.

CONCLUSION

Storage of PCs contributes to the hydrolysis of high-molecular-weight kininogen and generation of pharmacologically relevant BK levels that might pose a hazard in susceptible patients.

Aspect multifactoriel des effets secondaires aigus des inhibiteurs de l′enzyme de conversion de l′angiotensine

Angiotensin converting enzyme inhibitors are a class of drugs successfully used in the treatment of cardiovascular diseases. Despite their effectiveness, treatment with these drugs is characterized by chronic and acute side effects with variable expression depending on the clinical context. Angioedema occurs in patients with hypertension or heart failure. Anaphylactoid reaction is also reported in hemodialysis patients and severe hypotensive reaction in patients receiving transfused blood products and plasmapheresis. In this paper, we describe the role of kinins and metallopeptidases in the pathophysiology of these acute side effects. We also propose different experimental and clinical evidences which plead for an ecogenetic nature of these rare but life-threatening events.

Study of bradykinin metabolism by rat lung tissue membranes and rat kidney brush border membranes by HPLC with inductively coupled plasma-mass spectrometry and orthogonal acceleration time-of-flight mass spectrometry

The coupling of the techniques, high-performance liquid chromatography (HPLC), orthogonal acceleration time-of-flight mass spectrometry (OATOF-MS) and inductively coupled plasma mass spectrometry (ICP-MS) provides a very powerful method for identifying and quantifying the products of bradykinin metabolism. In this study, we were able to identify the major metabolites of bradykinin degradation reported in the literature. In addition, a new bradykinin metabolite corresponding to bradykinin 5,9 fragment (BK-(5,9)-fragment) was identified as a product of neutral endopeptidase (NEP) activity. This finding establishes that NEP cleaves bradykinin simultaneously at the positions 4-5 and 7-8. We also demonstrate the equivalent participation of NEP and angiotensin-converting enzyme (ACE) within the rat lung tissue membranes (RLTM) in bradykinin degradation, suggesting its suitability as a model for the assay of dual ACE/NEP inhibitors. On the contrary, in rat kidney brush border membranes (KBBM), ACE is not significantly involved in bradykinin metabolism, with NEP being the major enzyme.

Innate immunity in critical care

Innate and adaptive immunity are required for effective control of infection. Numerous breakthroughs have been achieved in the last 15 years with regard to the functioning of the innate immune system. This article focuses on new paradigms of microorganism recognition, discusses recently described (or rediscovered) cytokines that provide further insight into the development of sepsis, and reviews both pro- and anti-inflammatory pathways for control of infection. Finally, it discusses what has and has not worked with regard to controlling inflammatory pathways in septic patients.

The kallikrein-kinin system: current and future pharmacological targets

The kallikrein-kinin system is an endogenous metabolic cascade, triggering of which results in the release of vasoactive kinins (bradykinin-related peptides). This complex system includes the precursors of kinins known as kininogens and mainly tissue and plasma kallikreins. The pharmacologically active kinins, which are often considered as either proinflammatory or cardioprotective, are implicated in many physiological and pathological processes. The interest of the various components of this multi-protein system is explained in part by the multiplicity of its pharmacological activities, mediated not only by kinins and their receptors, but also by their precursors and their activators and the metallopeptidases and the antiproteases that limit their activities. The regulation of this system by serpins and the wide distribution of the different constituents add to the complexity of this system, as well as its multiple relationships with other important metabolic pathways such as the renin-angiotensin, coagulation, or complement pathways. The purpose of this review is to summarize the main properties of this kallikrein-kinin system and to address the multiple pharmacological interventions that modulate the functions of this system, restraining its proinflammatory effects or potentiating its cardiovascular properties.

Kallikrein-kinin system in hepatic experimental models

The purpose of this brief review is to describe some characteristics of the kallikrein-kinin system (KKS) in the liver. The liver synthesizes kininogens and prekallikrein and the synthesis of both proteins is increased in rats during the acute phase reaction. It is also the main organ to clear tissue as well as plasma kallikrein from the circulation in normal and pathological conditions. Bradykinin (BK), yielded by the kallikrein-kinin system, is a potent arterial hypotensive peptide, but in the liver it induces a portal hypertensive response. The portal hypertensive action of bradykinin is mediated by B2 receptors located on sinusoidal cells of the periportal region and is followed by its hydrolysis by angiotensin-converting enzyme, which is primarily present in the perivenous (centrolobular) region.

Effects of bradykinin on cardiovascular remodeling in renovascular hypertensive rats

Angiotensin converting enzyme (ACE) inhibitors inhibit both the formation of angiotensin II and the catabolism of bradykinin (BK). They prevent not only hypertension but also cardiac hypertrophy and fibrosis. An increase in BK level stimulates the expression of nitric oxide (NO) synthase (NOS) and induces prostaglandins, both of which are powerful vasodilator factors. The direct effect of BK against cardiac hypertrophy is still unclear. This study was performed to examine the cardioprotective effects of BK in hypertrophic models. Renovascular hypertensive (RHT) rats were treated with BK (1,000 ng/kg/day), BK+D-arginyl-[Hyp(3), Thi(5), D-Tic(7), Oic(8)]-bradykinin (HOE140) (a BK B(2) receptor antagonist), and BK+N(omega)-nitro-L-arginine methyl ester (L-NAME) (a NOS inhibitor) for 3 weeks. Blood pressure was measured and echocardiographic analysis performed during the treatment. Histological data were analyzed to confirm the hypotrophic effect of BK. Treatment with BK improved cardiac remodeling, reducing both the heart weight/body weight ratio and the left ventricular wall thickness. However, co-treatment with HOE140 or L-NAME reversed the anti-hypertrophic action of BK. In particular, cardiac fibrosis or perivascular fibrosis, along with collagen accumulation, were inhibited by treatment with BK, while HOE140 and L-NAME counteracted these changes. In addition, expressions of atrial natriuretic peptides (ANP) and brain natriuretic peptides (BNP), which are markers of cardiac abnormalities, were down-regulated by treatment with BK. These effects were reversed by co-treatment with HOE140 and L-NAME. Together, these results indicate that BK directly inhibits the progression of cardiac hypertrophy and cardiac fibrosis due to NO release via the BK B(2) receptor. The BK-NO pathway may play an important role in the progression of cardiac remodeling.

Hypotensive transfusion reactions can occur with blood products that are leukoreduced before storage

BACKGROUND

Leukoreduction before storage, rather than bedside white blood cell filtration, is recommended to prevent hypotensive transfusion reactions.

STUDY DESIGN AND METHODS

Investigation of hypotensive transfusion reactions during radical prostatectomy in two patients on angiotensin-converting enzyme inhibitors. In Patient A, hypotension occurred during the transfusion of each of the following blood products: 2 units of autologous blood deposited and leukoreduced (LR) before storage; 3 units of allogeneic red cells LR before storage; and 2 units of non-LR acute normovolemic hemodilution (ANH) whole blood. When each of the transfusions was stopped, the blood pressure recovered. In Patient B, hypotension occurred during the transfusion of non-LR ANH whole blood. All implicated units were administered rapidly using a blood infuser at 37 degrees C. Bradykinin (BK) and des-Arg9-BK formation and degradation and the activity of kinin-degrading metallopeptidases were measured in plasma samples from both patients.

RESULTS

Degradation of des-Arg9-BK was severely impaired and the activity of aminopeptidase P severely reduced in Patient A, but not in Patient B. BK degradation was mildly impaired in both patients.

CONCLUSION

Hypotensive reactions can occur with blood products that are LR before storage and non-LR ANH. An inherent defect in the metabolism of kinins may be a risk factor for the development of hypotensive transfusion reactions.

Role of bradykinin in angiotensin-converting enzyme knockout mice

Angiotensin-converting enzyme (ACE) plays a central role in the renin-angiotensin system. Whereas ACE is responsible for the production of angiotensin II, it is also important in the elimination of bradykinin. Constitutively, the biological function of bradykinin is mediated through the bradykinin B(2) receptor. ACE knockout mice have a complicated phenotype including very low blood pressure. To investigate the role of bradykinin in the expression of the ACE knockout phenotype, we bred B(2) receptor knockout mice with ACE knockout mice, thus generating a line of mice deficient in both the B(2) receptor and ACE. Surprisingly, these mice did not differ from ACE knockout mice in blood pressure, urine concentrating ability, renal pathology, and hematocrit. Thus abnormalities of bradykinin accumulation do not play an important role in the ACE knockout phenotype. Rather, this phenotype appears due to the defective production of angiotensin II.

Quality assessment of seven types of fresh-frozen plasma leucoreduced by specific plasma filtration

BACKGROUND AND OBJECTIVES

A study was undertaken to determine plasma quality after specific filtration.

MATERIALS AND METHODS

Seven types of plasma were tested, after filtration of plasma from filtered or non-filtered whole blood. Leucocyte counting was carried out after a 30-fold concentration of the sample. Twenty-nine parameters (including coagulation testing, proteins, coagulation factors and activation markers) were measured before and after filtration, and after 6 months of storage.

RESULTS

After specific plasma filtration, the average residual leucocyte counts were less than 2250/l. In spite of small statistically significant changes in proteins, coagulation factors and complement activation, this study showed that plasma filtration did not alter plasma quality. After 6 months of storage at -30 degrees C, factor VIII recovery varied between 91 and 109%. Haemostasis parameters and activation markers remained within the normal range.

CONCLUSIONS

Specific plasma filtration reduced the leucocyte number to < 104 leucocytes/l. The quality of plasma was not altered by the additional step of specific plasma filtration.

Correcting immune imbalance: the use of Prosorba column treatment for immune disorders

The treatment of selected refractory autoimmune diseases has been complemented by the use of Protein A (Prosorba column) immunoadsorption. US Food and Drug Administration-approved clinical applications include idiopathic thrombocytopenia purpura (ITP) and rheumatoid arthritis (RA). Other common off label uses include thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS). Less common experimental uses in diseases in which efficacy has been reported include autoimmune CNS syndromes, peripheral neuropathies, autoimmune pancytopenia, hemolytic anemia and solid organ transplant rejection. Prosorba column treatment is generally well tolerated but a small proportion of treated patients experience chills, fever, tremor, hypotension and rash. The mechanism of action suggested for the efficacy of the column is the restoration of normal immune balance and normal tolerance. Observations in ITP has suggested that column treatment stimulates a rise in anti-idiotype antibody directed against antiplatelet antibodies, effecting a decrease in pathogenic antiplatelet antibodies and immune complexes.

Leukoreduction of blood components

During the past year, blood component therapy witnessed two quite contradictory trends in the area of leukoreduction. On the one hand, the year saw widespread forced implementation of leukoreduction by several national blood suppliers, including the American Red Cross, who refused to sell hospitals nonleukoreduced blood. The forced implementation came at high cost to hospitals and with the strong endorsement of the US Food and Drug Administration, which stopped short of mandating universal leukoreduction in the United States. On the other hand, the year saw the publication of several pivotal clinical trials that failed to demonstrate significant patient benefit from the use of leukoreduced blood components. The emerging scientific and clinical evidence reviewed in this article demonstrates that leukoreduction technology is an effective means to reduce the risk of three complications of transfusion: HLA alloimmunization, cytomegalovirus transmission, and recurrent febrile nonhemolytic transfusion reactions. The application of the technology to all blood components does not appear to be warranted.

Hypotensive reaction during staphylococcal protein A column therapy in a patient with anomalous degradation of bradykinin and Des-Arg9-bradykinin after contact activation

BACKGROUND

Hypotensive reactions have occurred in patients taking angiotensin converting enzyme (ACE) inhibitors after infusion of blood previously in contact with negatively charged surfaces capable of generating kinins, which accumulate when ACE, a kininase, is inhibited. A patient with anomalous bradykinin (BK) metabolism who experienced hypotension during extracorporeal staphylococcal protein A (SPA) therapy while on an ACE inhibitor was studied.

CASE REPORT

A patient with mitomycin-associated hemolytic-uremic syndrome received SPA treatments after her ACE inhibitor, lisinopril, was held. Lisinopril was restarted before her 18th SPA treatment, and immediately after return of treated plasma she developed facial redness and hypotension, which resolved after the return stopped and recurred when restarted. To study formation and degradation of kinins, exposed her plasma to glass beads. We found a normal kinin formation rate but an abnormal degradation and accumulation of Des-Arg9-BK. The kinin degradation enzymes ACE, aminopeptidase P (APP), and carboxypeptidase N (CPN) were measured while on an ACE inhibitor, showing absence of ACE activity, low APP, but normal CPN.

CONCLUSION

This patient's vasodilation and hypotension during SPA therapy was associated with a pre- existing anomaly of BK metabolism. Her ACE inhibitor shifted degradation toward Des-Arg9-BK formation, and her low APP was associated with a prolonged t50 and accumulation of the vasoactive Des-Arg9-BK.

Angiotensin-converting enzyme inhibitor-associated angioedema is characterized by a slower degradation of des-arginine(9)-bradykinin

Angioedema (AE) is a rare but potentially life-threatening side effect of therapy with inhibitors of angiotensin-converting enzyme (ACE), the main bradykinin (BK)- inactivating metallopeptidase in humans. The pathogenesis of ACE inhibitor (ACEi)- associated AE (AE+) is presently unknown, although there is increasing evidence of a kinin role. We analyzed the metabolism of endogenous BK (B(2) receptor agonist) and its active metabolite, des-Arg(9)-BK (B(1) receptor agonist), in the presence of an ACEi during in vitro contact activation of plasma from hypertensive patients (n = 39) who presented AE+. Kinetic parameters were compared with those measured in a control group (AE-) of hypertensive patients (n = 39) who never manifested any acute or chronic side effects while treated with an ACEi. The different kinetic parameters were analyzed using a mathematical model (y = k t(alpha) e(-beta t)) previously applied to a normal, healthy population. The slope of BK degradation, but not its formation from high-molecular-weight kininogen, was lower in AE+ patients when compared with the AE- controls. des-Arg(9)-BK accumulation during the kinetic measurements was significantly higher in AE+ plasma. This accumulation of the B(1) agonist in AE+ patients paralleled its half-life of degradation. In conclusion, our results show, for the first time, that an abnormality of endogenous des-Arg(9)-BK degradation exists in the plasma of patients with ACEi-associated AE, suggesting that its pathogenetic mechanism lies in the catabolic site of kinin metabolism.