Review: heparin. 2. Effect on thrombocytes, vascular walls and fibrinolysis]

In a brief survey the impact on thrombocyte functions and thrombocyte values caused by heparin and its fractions is reported, with the acute and immuno-allergic form of heparin-induced thrombopenia being widely dealt with. Furthermore, the relationship between heparin and vessel wall, particularly then its endothelial layer, is discussed and finally, its impact on the mechanisms of fibrinolysis is reported.     

Heparin and antiheparin in childhood. 2. Clinical relevance of the phenomenon of heparin resistance

Investigations of the content of platelet factor 4 in different thrombocyte lysates and platelet-rich plasma after induced release reaction were aimed at checking the efficiency of the own antiheparin measuring system. In this connection, the age dependent dynamics of platelet factor 4 could be first discovered. In platelet-poor plasma of healthy grown-up test persons there was an evidence of antiheparin titres which were five times higher as compared with those persons born maturely. All patients with disseminated intravascular coagulation processes of different aetiology, however, will have significantly increased values. As demonstrated in two children with hyperpyretic toxicosis, the liberated platelet factor 4 will only show a short plasma half decay period. From investigations made for refinding heparin in the plasma after in vitro addition the conclusion can be drawn that, in addition to platelet factor 4, even unspecific adhesions of heparin to certain plasma proteins may be responsible for increasing heparin resistance.     

Hemostasis disorders after transfusions

Disturbances of haemostasis caused immunologically and non-immunologically were observed after transfusion of blood and blood derivatives. Transfusion of heparin blood increased the bleeding susceptibility only in case of pre-existing high-degree defects of haemostasis or if they were performed as massive or exchange transfusions. Massive transfusions with blood stored for a long time will induce complex defects. Under intensive substitution therapy of haemophilia A the so-called paradoxical bleeding will occur in spite of a high factor VIII level. These bleedings are supposed to be disturbances of the thrombocyte function and are caused by fibrin(ogen) derivatives. Post-transfusional thrombocytopenias may be brought to remission by repeated plasmapheresis. Factor specific inhibitory bodies will appear after substitution in a small percentage of haemophilic patients. 5 to 7 days after the onset of therapy an anamnestic reaction can be observed as a titre increase by leaps. Usually, the inhibitory titre will decrease to a mostly low basal value in the course of three to five months. The therapy with cyclophosphamide simultaneously started with the substitution will more frequently prevent the anamnestic reaction or reduce it. Titres with more than 5 units cannot be overcome at the beginning even by higher concentrations of preparations. The substitution therapy should be preceded by exchange transfusions or plasmapheresis of up to 25 units. With still higher titres only procedures of inhibitor-bypassing are possible with factor VIII preparations of animal origin or better with activated prothrombin complex preparations, such as FEIBA. Recent reports give evidence that permanent substitution with factor VIII concentrates at a highest dosage can eliminate the production of inhibitors completely.     

The effect of stabilizer composition on thrombocytes and thrombocyte function in stored whole blood. I. The thrombocyte count, thrombocyte aggregation and retraction during storage]

The behaviour of thrombocyte number and thrombocyte function aggregation and retraction in ACD, AcD-A and AcD-AG stabilized blood was examined in 18 apparently healthy test persons for a period of 9 days. On the one hand the addition of adenin or guanosin respectively increased the thrombocyte aggregation, on the other hand, however, a decrease of free, haemostatically efficient thrombocytes could be observed. Under the test conditions chosen retraction does not allow any statement to be made on the degree of the storage damage.     

Multivariate analysis for the understanding of typical diabetic hemostasis criteria. 2. Prevalent thrombocytic markers]

Various thrombocyte functions and metabolic criteria were investigated in 309 test persons, among them 198 Patients affected with diabetes mellitus, 67 of type I and 131 of type II as well as 111 healthy control persons. From the variety of these factors an optimal amount was determined by means of the statistical method of multivariance analysis separating both types of diabetes and healthy control persons. In addition to haemoglobin A1 concentration, thrombocyte parameters have been found together with the degree of capillary fragility, adrenalin-induced aggregation, platelet aggregation test and clot retraction, which allow individuals to be assigned diagnostically to various groups of test persons. Thus, thrombocyte functions found in both types of diabetes and normal persons exhibit differences which may contribute to a diagnostic classification.     

The effect of concanavalin A on the rat electro-olfactogram. Differential inhibition of odorant response.

When the rat olfactory mucosa is treated with concanavalin A, it subsequently shows diminished sensitivity towards 60% of the 112 odorants tested (as judged by the amplitude of the electro-olfactogram response). Odorants containing four to six carbon atoms tend to show the largest (absolute) diminutions, suggesting a receptor for this kind of odorant, although the structural specificity is weak. The receptor seems to be of particular importance in the detection of thiols, carboxylic acids and hydrocarbons of the above size, since these compounds loose the highest proportion of their original signal. The concanavalin A appears to be binding to the glycan of one or more cell-surface proteins. The binding may be at, or close to, at least one odorant receptor.     

Exposure to fenitrothion causes malfunctions of Spodoptera exigua Hübn. (Lep., Noctuidae) eggs

A long-term exposition of Spodoptera exigua (Hübner) larvae to fenitrothion caused abnormalities in egg structure. When examined under a scanning electron microscope, the eggs revealed diminutions and cracks around the micropylar and aeropylar region. The damage was proportional to the concentration of the insecticide. The observed changes may be one of the reasons for the decreased survival of populations exposed to fenitrothion.     

The effect of stabilizer composition on the thrombocytes and thrombocyte function in stored whole blood. II. Results of the thrombocyte spreading test]

The behaviour of thrombocyte spreading in ACD, AcD-A and AcD-AG stabilized blood was examined in 18 apparently healthy test persons for a storage period of 9 days. Due to an improved energy metabolism of thrombocytes the addition of adenin or guanosin respectively in ACD stabilized blood will cause the thrombocyte spreading to be widely preserved during storage.     

Failure of therapy with thrombocyte concentrates as a sequela of anti-Kob (3b) antibodies in a patient

The report deals with a failure in transfusing thrombocyte concentrates in a patient affected with bone-marrow hypoplasia caused by thrombocyte antibodies with anti-Kob (3b) specificity. This is referred to as a rare occurrence since, in general, HLA cytotoxins are identified as underlying cause and polyspecific or anti-Zwa(P1A1) antibodies only in exceptional cases.     

Phagocytic granulocyte function in hemoblastoses]

Judging from the spontaneous NBT reduction, the indices of phagocytosis and NBT, there is a moderate, but statistically significant diminution of these parameters in leukaemia and malignant lymphoma including plasmocytoma. Moreover, further diminutions could be identified during the acute stage of the disease (first diagnosis or recidive) in acute leukaemia and lymphogranulomatosis, but not for chronic myeloic leukaemia.     

The inhibition of tissue type plasminogen activator by plasminogen activator inhibitor-1. The effects of fibrinogen, heparin, vitronectin, and lipoprotein(a).

Plasminogen activator inhibitor-1 (PAI-1) regulates fibrinolysis by inhibiting tissue type plasminogen activator (t-PA). Fibrinogen, heparin, and vitronectin enhance the rate of inhibition of t-PA by PAI-1. Kinetic studies indicate that both fibrinogen and heparin increase the second-order inhibition constant by a maximum of approximately 4-fold, whereas vitronectin increases the rate constant by a maximum of approximately 6-fold. The dissociation constants of fibrinogen, heparin, and vitronectin for the inhibition reaction were 200 nM, 20 nM, and 600 pM, respectively. In addition, PAI-1 inhibition of t-PA may be regulated by the presence of lipoprotein(a) (Lp(a)). Previous studies demonstrated that Lp(a) competes with plasminogen for the active site of fibrinogen- and heparin-bound t-PA. Kinetic studies described here demonstrate that Lp(a) prevents the inhibition of t-PA by PAI-1 in the presence of fibrinogen and heparin, but has no effect on the reaction in the presence of vitronectin or in the absence of either fibrinogen or heparin. The data suggest that fibrinogen and heparin may enhance the rate of inhibition through an interaction with t-PA, and that vitronectin may enhance the inhibition through an interaction with PAI-1. In addition, these experiments indicate that Lp(a) may regulate fibrinolysis by competing with PAI-1 and plasminogen for fibrinogen- and heparin-bound t-PA. These data suggest that PAI-1 inhibition of t-PA in vivo is primarily mediated via interaction with fibrinogen, heparin, vitronectin, and Lp(a), and therefore, the functional levels of PAI-1 activity in the vasculature may be regulated by the presence of these components.     

Effets de la chirurgie á coeur ouvert sur les mécanismes de défense contre lea infections bactériennes

Extracorporeal circulation during open-heart surgery may damage cellular and humoral factors in the blood. Phagocytic functions of circulating polymorphonuclear leukocytes were investigated in 10 patients 1 day before, then 1 hour, 2, 4 and 10 days after open-heart surgery. Transient diminutions in the phagocytic capacity of polymorphs was found for Staphylococcus aureus and Escherichia coli in one patient, and E. coli only in two patients up to the 4th postsurgical day. A positive correlation was found between the duration of extracorporeal circulation and the transient diminutions in phagocytic capacity for these three patients. However, the bactericidal capacity of polymorphs and their capacity to reduce nitroblue tetrazolium were normal in all patients. The serum concentrations of total hemolytic complement, C3, IgG and IgM were generally diminished up to the 4th day after surgery, but the opsonic power of the serum was almost normal in all the patients.     

Heparin influence on the complex of serum amyloid P component and complement C4b-binding protein

Serum amyloid P component (SAP) forms a calcium-dependent complex with C4b-binding protein (C4BP) in human serum. this study demonstrated that heparin interacted with SAP in a calcium-dependent manner and prevented formation of the SAP.C4BP complex. Furthermore, the SAP-heparin interaction interfered with SAP binding to membranes. Therefore, all three of these interactions involved similar sites on SAP, or each interaction sterically obstructed the other binding sites. In addition to heparin, SAP bound to heparan sulfate and chondroitin sulfate. In each case, a distinct multimeric species was generated. Gel filtration and sucrose density gradient ultracentrifugation suggested that heparin and heparan sulfate produced a dimer of SAP. The dimer appeared to be the most stable structure since it was not dissociated by excess heparin. While low molecular weight heparin interacted with SAP and inhibited SAP association with membranes, the SAP dimer was not detected in sucrose density gradient ultracentrifugation studies. Polybrene prevented the interaction between SAP and heparin in both a purified system and in human serum that was enriched in SAP and heparin. In contrast, Polybrene did not seem to alter the SAP.C4BP complex. While the function of the SAP.C4BP complex is unknown, it may be important for regulation of complement and/or transport of SAP to sites in the body. Dissociation of the SAP.C4BP complex by sulfated polysaccharides such as heparin may be a physiological response that could be important during tissue damage or complement activation.     

Evaluation of clinical efficacy of platelet substitution in acute leukemia using resonance thrombography

For evaluating the clinical effectiveness of thrombocyte substitution, the resonance thrombogram was registered before and after thrombocyte substitution in 50 patients with acute leukemia and the increase of thrombocytes (corrected increment) determined. Thrombocyte substitution led to a significant diminution of the platelet amplitude (p less than 0.01) and platelet value. The highest value of these alterations of parameters was reached 1 hour after transfusion, it was somewhat lower after 24 hours, yet the initial value was not reached again. Correlations could be found to exist between the platelet amplitude and the corrected thrombocyte increase 1 hour and 24 hours after transfusion. The resonance thrombography enables the successful control of thrombocyte substitution to be made and it is suitable for monitoring hemostasis in severe thrombocytopenia due to production.     

The oxidative mechanism of heparin interferes with radical production by glucose and reduces the degree of glycooxidative modifications on human serum albumin.

Among substances which may prove useful in preventing or reducing the progression of glycooxidative modifications of proteins, heparin plays a unique role. To elucidate the mechanism whereby heparin may favourably influence the protein structure during glycation, human serum albumin (HSA) was glycated with both 25 and 50 mM glucose in the absence and presence of 12 microg.mL(-1) low-molecular-mass heparin. Glycation caused: (a) modifications of fluorescence emission and excitation spectra consistent with the covalent attachment of glucose to protein; (b) a significant increase in the esterase activity of HSA on p-nitrophenyl acetate; (c) a reduced susceptibility to tryptic digestion and (d) enhanced formation of high-molecular mass aggregates of HSA. These alterations were accompanied by oxidative reactions, as the EPR spectra showed a clear-cut radical signal, dependent on glucose concentration, further confirmed by measurement of the carbonyl content of HSA, as an indirect proof of oxidative damage. In the presence of heparin all the above alterations, especially at 25 mM glucose, turned out to be antagonized. The effects of heparin were dependent on its specific binding to HSA, which triggered an oxidative mechanism strikingly different from that caused by glucose. In the presence of heparin, only the radical species catalyzed by heparin was detected across all samples of glycated HSA, irrespective of glucose concentration. In addition, at 25 mM glucose, enhancement of the oxidative capacity of heparin was also observed. The results demonstrate that the oxidative mechanism sustained by heparin mediates biological effects that may be beneficial in reducing the extent of glycooxidative damage on HSA.     

The question of thrombocyte substitution as a prophylactic measure in splenectomy for idiopathic thrombocytopenic purpura (ITP)]

The problem of intraoperative thrombocyte transfusion in splenectomy of patients with ITP is discussed. The indication for splenectomy cannot be equalized with that for intra-operative platelet substitution. Thrombocyte kinetic examinations with a concurrent determination of the thrombocyte turnover enable those patients to be recognized by their bleeding tendency who are particularly endangered by operations. The intraoperative platelet substitution should be limited to those patients with ITP whose turnover is markedly lowered as a manifestation of reduced thrombocytopoiesis. In these cases it is advisable to shift splenectomy to a later date.     

Platelet spreading in diabetes mellitus

In 162 test persons divided into healthy control persons and diabetics of type I and type II the thrombocyte spreading was investigated according to the method of Breddin. Age, sex, degree of seriousness of retinopathy, duration of diseases, present level of blood sugar and HbA1 concentration were taken into account. Spread thrombocyte forms were increasingly found in old age, in diabetics of both types and a close relation to the extent of retinopathy was evident. As diabetic retinopathy became evident and with growing degree of seriousness, spread forms of thrombocytes were increasingly found, so that the increased spreading capacity may be interpreted as a disturbed metabolic and blood vessel situation in diabetes mellitus.     

Studies of thrombocyte function in CPD blood]

The CPD stabilizer according to Gibson with an addition of 1.25 mMol adeninesulfate and 2.50 mMol guanosine is used in blood storage for better preserving 2.3-bis-phosphoglycerate of erythrocytes. Here platelet-rich CPD plasma was investigated before and during a 3 days storage at 4 degrees C or room temperature with regard to preserving the global thrombocyte function. The latter consists in the ability to seal blood vessels and is tested by means of pressure registration in combined thrombocyte-aggregation-adhesion (DKTA method) as an ability to close the pores of a sieve by adding 10(-5) mM/l of ADP. At room temperature this thrombocyte function is approximately 0 following 3 days of storage in CPD plasma excess without shaking. When stored at 4 degrees C it is preserved to a slight degree. Loss of thrombocyte function will depend on pH, thus being particularly evident at room temperature.     

Thrombocyte substitution in acute leukemia. Effect of histocompatibility on the clinical efficacy

Thrombocyte substitution is an essential prerequisite for intensive cytoreductive therapy in acute leukemia. Evaluating 228 thrombocyte transfusions in 17 patients shows that the clinical effectiveness of thrombocyte concentrates can be increased by making the coordination of HLA antigens of donor and receiver as good as possible. When measured in the corrected increment (CI) 24 hours after transfusion, the effectiveness of A3/B1 match preparations (CI = 7.0 +/- 1.6) is significantly higher than that of random preparations (CI = 3.0 +/- 0.5). With the presence of HLA antibodies an effective substitution (CI24 greater than or equal to 4.5) can only be achieved by A3/B1 match thrombocytes. This can only be realized by applying the fourfold thrombapheresis of single donors.