Labelling of Blood Platelets with Stable Tracers

Half-time values of platelets labelled with stable rubidium are compared to those of platelets labelled with Cr51. Platelets labelled with stable rubidium are assayed by a very simple version of the X-Ray fluorescence equipment. The mean quantity of rubidium incorporated by the cells is of about some µg Rb per ml blood.

The in vitro half-time of human Rb labelled platelets stored at 22° C is 41.2 ± 3h compared with the value 44.8 ± 3h for platelets labelled with Cr51, as deduced by six experiments. The in vivo half-time of rabbit platelets labelled with stable rubidium is 22 ± 3h compared with the value 18 ± 3h of platelets labelled with Cr51; ten experiments were carried out.

The In Vitro Inhibitory Effect on Thrombin by 2,3-Diphosphoglycerate

Thrombin, incubated with 2,3-diphosphoglycerate (150 nmol 2,3-DPG/1 NIH thrombin unit) lost up to 70% of its clotting activity, whereas the esterase activity remained unchanged. No fibrinopeptide release by thrombin was observed in the presence of 2,3-DPG. The fibrin polymerization was normal. By chromatography on Amberlite IRC-50, α-thrombin was eluted at pH 8.0. In presence of 2,3-DPG, α-thrombin was not eluted. Likely, 2,3-DPG can interfere with thrombin.

Cyanide Insensitive Oxidase in Platelets of Newborn Infant

The authors studied the behaviour of neonate platelet O2 consumption after the addition of pyridine nucleotide compared to adult controls.

O2 consumption of neonate platelets after NADH addition was 103,2 mμmol O2/109/hr (SE = 24,74) and in adult controls 188,8 mμmol O2/109/hr (SE = 36,46).

After the addition of NADPH O2 consumption was, respectively, 233,5 mμmol (SE = 46,29) and 218,3 mμmol (SE = 30,01).

Oxygen Consumption in Platelets of Newborn Infants before and after Stimulation by Thrombin

The authors compared the oxygen consumption in platelets from the umbilical cord blood of 36 healthy newborn infants with that of 27 adult subjects, before and after thrombin addition (1.67 U/ml). Oxygen consumption at rest was 6 mμmol/109/min in adult control platelets and 5.26 in newborn infants. The burst in oxygen consumption after thrombin addition was 26.30 mμmol/109/min in adults and 24.90 in infants. Dinitrophenol did not inhibit the burst of O2 consumption in platelets in 8 out of 10 newborn infants, while the same concentration caused a decrease in 9 out of 10 adult subjects. Deoxyglucose inhibited the burst in O2 consumption in newborn infant and adult platelets by about 50%. KCN at the concentration of 10−4 M completely inhibited basal oxygen consumption but did not completely inhibit the burst after thrombin. At the concentration of 10−3 M, it inhibited both basal O2 consumption and the burst in infants and adult subjects.

Gender disparity in pediatric diseases

Sex/gender differences in terms of incidence, prevalence, age at onset and severity have been documented for several complex adulthood diseases. However, several pediatric diseases also displayed a gender disparity. Unfortunately, epidemiologic studies investigating gender disparity in pediatric age show dissimilar results often depending on the spatial and temporal issues, to considerable regional environmental variations, to social conditions or to infectious agent virulence. Anyway, studies over time showed that gender disparity in childhood mortality and morbidity may be narrow in some pathological conditions whereas in other severe diseases, e.g. sepsis, some cancers and some immune disorders, the disproportion was found as significant. In this work we briefly review literature data dealing with sex/gender differences in morbidity and mortality observed during the pediatric age. In particular, communicable and non-communicable diseases, including cancer, have been considered. The possible mechanisms underlining these differences, e.g. hormonal and epigenetic, are also discussed. The analysis of literature available as concerns pediatric age seems to underline that gender differences start very early in human beings and that hormones as well as gene expression in XX and XY cells can play a role. A reappraisal of the gender issue in pediatric research could thus be pivotal: it might contribute to the improvement of diagnostic and therapeutic strategies as well as to the improvement of the appropriateness of the cures.

Combined thrombolytic therapy for atrial thrombus in a preterm infant

Intracardiac thrombosis is a rare event in newborn (5.1 per 100000 live births). It is associated with an high morbidity and mortality. Most of intracardiac thrombi are related to intravascular catheterism. The use of thrombolytic therapy in neonates has rapidly improved in the last few years, particularly with the introduction of more clot-selective second-generation agents like urokinase and tissue plasminogen activator. In literature there is no therapeutic trial concerning the pharmacological approach of atrial thrombosis in newborns; different approaches are described in the case reports present in literature. In all of them, tissue plasminogen activator or urokinase are alternatively administered. In no case report urokinase and tissue plasminogen activator are administered in a combined thrombolytic therapy. Combined thrombolytic therapy with urokinase and tissue plasminogen activator, in association with low-dose heparin, allows the use of lower drug doses, less therapy's duration and a rapid resolution of thrombus. Thormbolytic therapy is sometimes complicated with hemorrhagic complications. This article describes the case of a preterm infant (25 weeks of gestational age) with peduncolate thrombus in the right atrium, treated with combined thrombolytic therapy. The authors noticed a rapid decrease in thrombus dimension, no thrombus replacement and no organ bleeding.

Increased frequency of immunoglobulin (Ig)A-secreting cells following Toll-like receptor (TLR)-9 engagement in patients with Kawasaki disease

Kawasaki disease (KD) is an acute vasculitis affecting mainly infants and children. Human B cells express Toll-like receptor (TLR)-9, whose natural ligands are unmethylated cytosine-guanine dinucleotide (CpG) motifs characteristic of bacterial DNA. The aim of this study was to clarify the pathogenesis of KD analysing the activation status of peripheral blood mononuclear cells (PBMC), focusing on B lymphocyte activation and functions. Ten patients and 10 age-matched healthy donors were recruited from the Bambino Gesù Hospital of Rome, Italy and enrolled into this study. We determined phenotype profile and immunoglobulin (Ig) production of PBMC from KD patients and age-matched controls. We found that the frequency of CD19(+) B lymphocytes and CD19(+) /CD86(+) activated B lymphocytes from KD patients during the acute phase before therapy was increased significantly. Moreover, B lymphocytes of acute-phase KD patients were more prone to CpG oligodeoxynucleotide (ODN) activation compared with the age-matched controls, as assessed by a significant increase of the number of IgA-secreting cells (SC). In the same patients we found a marked increase of IgM, IgG, interleukin (IL)-6 and tumour necrosis factor (TNF)-α production compared with the control group. In addition, in two convalescent KD patients, conventional treatment with intravenous immunoglobulin (IVIG) restored the normal frequency of CD19(+) B cells, the number of IgA-, IgM- and IgG-SC and the production of IL-6 and TNF-α. Our findings indicate that the percentages of peripheral B lymphocytes of acute-phase KD patients are increased and are prone to bacterial activation in terms of increased numbers of IgA-SC and increased production of IL-6 and TNF-α inflammatory cytokines. Thus, our data support the hypothesis of an infectious triggering in KD.

Effect of amlodipine on exercise-induced platelet activation in patients affected by chronic stable angina

BACKGROUND

Literature concerning exercise-induced platelet activation in chronic stable angina is somewhat confusing. The reason lies in the type of exercise as well as in methodological problems. A powerful, recently introduced procedure to detect platelet activation is flow cytometry. Platelet response to activating factors is mediated by calcium uptake; however, calcium antagonist effect on platelet activity is still unclear.

HYPOTHESIS

The study was undertaken to investigate exercise-induced platelet activation before and after treatment with amlodipine in chronic stable angina.

METHODS

Twenty patients with chronic stable angina were entered into the study. Each subject underwent a symptom-limited cycloergometer stress test following a washout period of 2 weeks. Blood samples were collected before and immediately after exercise. All subjects were then randomized into two groups of 10 patients each, with Group 1 and Group 2 taking amlodipine 10 mg/day, and placebo for 4 weeks, respectively. They subsequently underwent a second exercise stress test, and blood samples were obtained before and immediately after exercise. Flow-cytometric evaluation of platelet activity was performed in order to recognize GMP-140 expression on platelet membrane.

RESULTS

Strenuous exercise induced a significant increase in platelet activation in all subjects prior to therapy. No significant differences were observed in platelet activity at rest between Groups 1 and 2, whereas a significant decrease in exercise-induced platelet activation was demonstrated in Group 1 compared with Group 2.

CONCLUSION

Our data provide evidence of the favorable effect of amlodipine on exercise-induced platelet activation in patients affected by chronic stable angina.

[Antithrombin III in burned children]

We studied haemostatic parameter and Antithrombin III (ATIII) level in 50 consecutive admissions for severe burns between 1990 to1994 to the Centro Grandi Ustionati Ospedale S. Eugenio, Rome. The criteria for inclusion in the study were age <16 years and the presence of major burns (extent of the burns >30 and second and third degree burns). Treatment consisted of initial fluid resuscitation and early excision and grafting of burn wounds and critical care support by a multidisciplinary team. Burn-related variables haemostatic values and the conditions of microcirculation were proposed and analysed with the help of Fisher exact test, chi square test, logistic regression and discriminant analysis. By the discriminant analysis, the coefficients of the standardized functions and the percentage of correctly classified individuals were calculated. The analysis showed total burned surface turned out to be the best predictor of survival. High discrimination efficiency was observed for age, weight, burn type (flame, scald contact chemical electrical). By the logistic regression, the total burned surface confirmed to be the best predictor of survival and between the haemostatic variables ATIII give a significant value (p=0.0244). Moreover, it is noteworthy that ATIII level at the onset of the disease gives a significant correlation with mortality (p=0.0005). The Fisher test showed a significant association between ATIII level and death (p=0.0005). This was confirmed by the chi square test (p=0.00027). Considering the AT deficiency in patients with thermal injuries, we conducted a pilot study to assess AT concentrate infusions for safety and efficacy in thermal injury. The patients received AT concentrate infusions every 8 hours to raise the plasma level to 100 % in the first 72 hours after injury and were compared with control patients with burns. Day4 levels were 105%+/-20% in patients treated with AT patients versus 50%+/-14% in the control patients (P < 0.001). In the group treated with AT the time to microcirculation recovery was shorter (P<0.02).

Involvement of oxygen radicals in cytarabine-induced apoptosis in human polymorphonuclear cells

We investigated apoptosis in polymorphonuclear neutrophils (PMNs) induced by cytarabine (Ara-C). This drug increased apoptosis by 100% with respect to the controls after 3 hr of incubation. This increase was inhibited by N-acetyl-L-cysteine (NAC) or diphenyleneiodonium chloride (DPI). Ara-C alone caused an early increase (after a 30-min incubation) in intracellular oxidant generation (inhibitable by rotenone, fumonisin b1, and DPI) and in protein tyrosine phosphorylations (inhibitable by NAC). The drug also affected the observed reduction of dimethylthiazol diphenyltetrazolium bromide (MTT). No extracellular release of reactive oxygen species (ROS) was elicited by the addition of Ara-C, while the drug increased the release of ROS by N-formyl-leucyl-phenylalanine-(f-MLP) but not phorbol 12-myristate 13-acetate-stimulated PMNs. This phenomenon was abolished by the addition of genistein, whereas such an effect was not observed following the addition of 1-(5-isoquinolynilsulfonyl)-2-methylpiperazine (H7). Ara-C induced ROS release from PMNs in the presence of subthreshold concentrations of f-MLP (priming effect). These results indicate that intracellular ROS production from mitochondria promotes Ara-C-induced apoptosis. Ara-C primes plasma membranes by a mechanism involving protein tyrosine phosphorylations and may also contribute to ROS generation from the granules.

Human platelets bind and degrade 2-arachidonoylglycerol, which activates these cells through a cannabinoid receptor

The endocannabinoid 2-arachidonoylglycerol (2-Delta(4)Ach-Gro) activates human platelets in platelet-rich plasma at physiological concentrations. The activation was inhibited by selective antagonists of CB(1) and CB(2) cannabinoid receptors, but not by acetylsalicylic acid. Human platelets can metabolize 2-Delta(4)Ach-Gro by internalization through a high affinity transporter (K(m) = 300 +/- 30 nM, V(max) = 10 +/- 1 pmol.min(-1).mg protein(-1)), followed by hydrolysis by a fatty acid amide hydrolase (K(m) = 8 +/- 1 microM, V(max) = 400 +/- 50 pmol.min(-1).mg protein(-1)). The anandamide transport inhibitor AM404, and anandamide itself, were ineffective on 2-Delta(4)Ach-Gro uptake by platelets, whereas anandamide competitively inhibited 2-Delta(4)Ach-Gro hydrolysis (inhibition constant = 10 +/- 1 microM). Platelet activation by 2-Delta(4)Ach-Gro was paralleled by an increase of intracellular calcium and inositol-1,4,5-trisphosphate, and by a decrease of cyclic AMP. Moreover, treatment of preloaded platelet-rich plasma with 2-Delta(4)Ach-Gro induced an approximately threefold increase in [(3)H]2-Delta(4)Ach-Gro release, according to a CB receptor-dependent mechanism. On the other hand, ADP and collagen counteracted the activation of platelets by 2-Delta(4)Ach-Gro, whereas 5-hydroxytryptamine (serotonin) enhanced and extended its effects. Remarkably, ADP and collagen also reduced [(3)H]2-Delta(4)Ach-Gro release from 2-Delta(4)Ach-Gro-activated platelets, whereas 5-hydroxytryptamine further increased it. These findings suggest a so far unnoticed interplay between the peripheral endocannabinoid system and physiological platelet agonists.

Surface reactions of a plasma-sprayed CaO-P2O5-SiO2-based glass with albumin, fibroblasts and granulocytes studied by XPS, fluorescence and chemiluminescence

X-ray photoelectron spectroscopy (XPS) was used to define the chemical composition of the outermost surface layer and the surface modification of a plasma-coated phospho-silicate glass (identified as BVA) when immersed in K-phosphate buffer or in phosphate buffered human albumin solution. Its behavior was compared with that of a soda-lime-based glass (identified as BVH) treated in the same way. The surface % composition of plasma-sprayed glass was consistent with bulk composition. After incubation with buffer, a Ca-P-rich layer developed only on the surface of BVA glass. Human serum albumin was bound reversibly to both glasses maintaining its native state. However, the protein completely covered the BVA glass surface within 24 h, with the formation of a mixed albumin-Ca-P layer, while 4 days incubation was necessary for complete coverage of BVH glass surface. Murine fibroblasts seeded on plasma-coated BVA glass showed a proliferation pattern similar to that of control cells grown on Petri dish, while cells seeded on BVH had more restricted growth. A limited response was induced in polymorphonuclear granulocytes by both bulk glasses powder. In conclusion, the glass identified as BVA has the suitable characteristics of its surface layers to be considered biologically active from both a chemical and a cellular point of view.

Spectrin changes occur in erythrocytes from patients with Fanconi's anemia and their parents

Fanconi's anemia (FA) is a clinically and genetically heterogeneous disease which has been hypothesized to be defective in the detoxification of reactive oxygen species. In this work we report the results obtained by morphometric analyses on the red blood cells (RBCs) from FA patients and their parents. We found that a high rate of erythrocytes from both homozygous and heterozygous subjects was significantly altered. RBCs underwent in fact cytoskeleton-dependent modifications, in particular of spectrin molecule, leading to cell shrinking and blebbing. We hypothesize that these changes may be the result of an oxidative imbalance that probably lead to alterations of RBC plasticity- and deformation-associated functions. Moreover, our results also suggest the possibility to identify FA carriers by the existence of RBC abnormalities.

Acute childhood idiopathic thrombocytopenic purpura: AIEOP consensus guidelines for diagnosis and treatment. Associazione Italiana di Ematologia e Oncologia Pediatrica

BACKGROUND AND OBJECTIVE

A recent evaluation carried out by the Associazione Italiana di Ematologia e Oncologia Pediatrica (AIEOP) about practice management of acute childhood idiopathic thrombocytopenic purpura (ITP) revealed a remarkable difference of behaviors among the different AIEOP centers. A need for common practice guidelines for this frequent illness arose from this observation. Our aim was to make the diagnosis and treatment of childhood ITP uniform. In the future we will evaluate the influence of these guidelines on practice behaviors.

DATA SOURCES AND METHODS

Our main reference was the 1996 document produced by the American Society of Hematology (ASH). Their recommendations were updated with information from literature searched for in the MEDLINE database (June 1996-October 1998); search terms included: thrombocytopenia, ITP, diagnosis, therapy, children. The computerized search retrieved 83 articles.

DATA EXTRACTION

the scientific validity of the literature was evaluated by a panel of members using published guidelines. The strength of the evidence was assessed using level of evidence criteria. Only data from level I and level II studies were taken in account. Only one study out of the 83 retrieved articles met these selection criteria and it was considered in addition to the 11 out of 581 articles selected in the ASH ITP guidelines. This preliminary work pointed out each issue about ITP not addressed by clinical studies and all participants in a Consensus Conference expressed their opinion about these issues.

RESULTS

Diagnosis is essentially based on history, physical examination, a complete blood count and an examination of the peripheral blood smear. Treatment is recommended taking into account the clinical picture and number of platelets. The main difference between these guidelines and those from ASH are: AIEOP guidelines rely on the opinion of the members of the consensus conference, ASH ones on a panel of experts; therapeutic options include only products available in Italy; the indications to treatment rely more on clinical picture than on platelet number.

INTERPRETATION AND CONCLUSIONS

These are explicitly developed, evidence-based practice guidelines to assist Italian pediatricians in making decisions about diagnosis and appropriate health care for patients with acute childhood ITP.

Cytoskeleton alterations of erythrocytes from patients with Fanconi's anemia

Fanconi's anemia (FA) is a very rare genetically heterogeneous disease which has been hypothesized to be defective in the detoxification of reactive oxygen species. In this work we report the results obtained by morphometric and biochemical analyses on the red blood cells (RBCs) from FA patients. With respect to RBCs from healthy donors the following changes have been detected: (i) a variety of ultrastructural alterations, mainly surface blebbing typical of acanthocytes and stomatocytes; (ii) a significant quantitative increase of these altered forms; (iii) modifications of spectrin cytoskeleton network; (iv) an altered redox balance, e.g. a decreased catalase activity and significant variations in the GSSG/GSH ratio. We hypothesize that remodeling of the redox state occurring in FA patients results in cytoskeleton-associated alterations of red blood cell integrity and function.

Anandamide activates human platelets through a pathway independent of the arachidonate cascade

Anandamide (arachidonoylethanolamide, AnNH) is shown to activate human platelets, a process which was not inhibited by acetylsalicylic acid (aspirin). Unlike AnNH, hydroperoxides generated thereof by lipoxygenase activity, and the congener (13-hydroxy)linoleoylethanolamide, were unable to activate platelets, though they counteracted AnNH-mediated stimulation. On the other hand, palmitoylethanolamide neither activated human platelets nor blocked the AnNH effects. AnNH inactivation by human platelets was afforded by a high-affinity transporter, which was activated by nitric oxide-donors up to 225% of the control. The internalized AnNH could thus be hydrolyzed by a fatty acid amide hydrolase (FAAH), characterized here for the first time.

Livedo vasculopathy vs small vessel cutaneous vasculitis: cytokine and platelet P-selectin studies

OBJECTIVE

To assess the role of platelets and lymphocyte-related immunological mechanisms in livedo vasculopathy (LV) and cutaneous small vessel vasculitis (CSVV). Livedo vasculopathy is thought to be related to the thrombotic occlusion of small and medium-sized dermal vessels. Cutaneous small vessel vasculitis comprises a heterogeneous group of disorders in which the main pathogenetic events could be modulated by circulating cytokines.

DESIGN

Case series study of 2 groups of patients affected respectively with LV and CSVV.

SETTING

A large clinical and research institute for the study and treatment of cutaneous diseases.

PATIENTS

Consecutive patients with clinically and histologically proved idiopathic LV (n = 8) and CSVV (n = 20) were studied and compared with healthy donors (n = 20). Patients with potentially correlated systemic diseases were excluded.

MAIN OUTCOME MEASURES

Surface expression of platelet P-selectin and circulating level of interleukin (IL) 1beta, tumor necrosis factor alpha (TNF-alpha), IL-8, IL-2, and soluble IL-2 receptor.

RESULTS

The IL-2 and soluble IL-2 receptor levels were significantly higher in serum samples from patients with both LV (1.24 +/- 0.46 IU/mL [mean +/- SD] vs 0.46 +/- 0.24 IU/mL, P<.001; 899 +/- 368 IU/mL vs 628 +/- 132 IU/mL, P<.02) and CSVV (0.91 +/- 0.57 IU/mL, P<.02; 1087 +/- 451 IU/mL, P<.001) than in those from the healthy controls. The serum levels of IL-1beta, TNF-alpha, and IL-8 were higher in patients with CSVV than in controls (7.53 +/- 6.7 pg/mL vs 4.58 +/- 2.72 pg/mL; 23.7 +/- 12.6 pg/mL vs 10.82 +/- 2.46 pg/mL, P<.001; 37.8 +/- 46 pg/mL vs 8.25 +/- 3.53 pg/mL, P<.02, respectively). No significant difference in the serum levels of IL-1beta (7.2 +/- 4.9 pg/mL), TNF-alpha (12.9 +/- 3.47 pg/mL), and IL-8 (5.9 +/- 4.13 pg/mL) was observed in patients with LV compared with controls. An increased expression of platelet P-selectin was also detected in patients with LV in comparison with controls and patients with CSVV. The mean +/- SD percentage of positive cells for P-selectin was 43% +/- 5% in the patients with LV, 5.1% +/- 2% in the controls (P<.001), and 5.3% +/- 2% in the patients with CSVV (P<.001).

CONCLUSIONS

Taken together, these data demonstrate that different pathogenetic mechanisms are operative in LV and CSVV. In fact, platelet and lymphocyte activation is present in LV, whereas the levels of inflammatory mediators are in a normal range. In CSVV, the high serum levels of proinflammatory cytokines suggest that they are actively involved in the pathogenesis of cutaneous vasculitis.

Fibroblast growth and polymorphonuclear granulocyte activation in the presence of a new biologically active sol-gel glass

The search for chemical devices to be used in clinical orthopaedics must find substances that are biocompatible and do not elicit inflammatory responses in vivo. To this end, a new form of glass has been prepared, composed of 8.1% CaO, 2.9% P2O5, 6.7% N2O5 and 82.3% SiO2, using sol-gel procedures. In order to evaluate the in vitro biocompatibility of this glass, the proliferation of cultured murine fibroblasts and the activation of human polymorphonuclear leukocytes has been studied. The performance of the sol-gel glass has been compared with that of a biocompatible non-resorbable soda-lime glass. Unlike the soda-lime glass, the sol-gel glass neither caused the inhibition of fibroblast growth nor elicited a marked inflammatory response by polymorphonuclear leukocytes, as demonstrated by chemiluminescence assay for reactive oxygen metabolites.

Superoxide release by human polymorphonuclear leukocytes in the presence of deferoxamine

BACKGROUND AND OBJECTIVE

Anecdotal reports in patients with acute and chronic iron overload have recently indicated that the efficacy and safety of an alternative chelation program including intravenous and/or continuous delivery of deferoxamine (DFO) may be in contrast with the risk of developing lung injury. Production of oxygen radicals has been postulated to be an important mechanism by which polymorphonuclear leukocytes (PMNs) could cause tissue injury in patients undergoing this alternative treatment method.

METHODS

PMNs obtained from healthy donors were incubated at 37 degrees C for 30 min with DFO (across the drug concentration 0.125 to 10 mg/mL). Superoxide (O2) production was measured by superoxide inhibitable cytochrome c reduction as well as by an NBT densitometric kinetic test. In the same run the effect of lipid peroxidation was demonstrated by means of a malonyl-dialdehyde (MDA) assay.

RESULTS

Preincubation of PMNs with any study concentration of DFO significantly enhanced O2 release as well as MDA production upon PMA stimulation. Maximal intracellular and extracellular O2-release as well as MDA production occurred at certain drug concentrations.

INTERPRETATION AND CONCLUSIONS

Our in vitro findings suggest that O2-release may be an additional detrimental contribution to tissue injury in some patients who develop pulmonary toxic effects while on intravenous and/or continuous DFO administration.

Fanconi anaemia in Italy: high prevalence of complementation group A in two geographic clusters

Cell fusion studies using lymphoblastoid cell lines from Fanconi anaemia (FA) patients have identified five complementation groups (FA-A to FA-E) among European FA patients. In Italy, of the 45 FA families referred to the Italian Registry of Fanconi Anaemia (RIAF), 15 took part in a project for the identification of complementation groups. Since three immortalized lymphoblast lines were resistant to a cross-linking agent, we analysed only 12 patients by complementation analysis and found that 11 belong to complementation group A. Four and seven families came from two geographic clusters in the Veneto and Campania regions, respectively, which are thought to consist of aggregates of related families in reproductive isolation. The clinical characteristics of the patients showed both intra- and interfamilial heterogeneity, although overall the disease had a relatively mild course. Since the populations in both Veneto and Campania are likely to represent genetic isolates, our finding predicts linkage disequilibrium for markers flanking the FAA gene. DNAs from these FA families may thus be utilized for positional cloning of this gene through haplotype disequilibrium mapping.

Effect of insulin on hydrogen peroxide production by human polymorphonuclear leukocytes. Studies with monoclonal anti-insulin receptor antibodies, and an agonist and an inhibitor of protein kinase C

This study evaluated the effect of insulin on the respiratory burst of human polymorphonuclear leukocytes (PMNLs) and the signalling pathways involved in this process, especially the involvement of protein kinase C (PKC). Isolated human PMNLs from healthy volunteers were incubated with different concentrations of insulin (10-10-10-7 mol/l) and for different durations of incubation (5-90 min). The intracellular production of hydrogen peroxide (H2O2) was detected employing a previously validated flow cytometric assay using 2',7'-dichlorofluorescein-diacetate (DCFH-DA) as a marker for H202 production. Specificity of insulin action was verified using an insulin antagonist (the monoclonal antibody MA-10). To identify the signalling pathway involved, we used; (a) monoclonal antibody MA-5, directed against the alpha-subunit of the insulin receptor, that partially mimics insulin without activating tyrosine kinase; (b) H7, an inhibitor of PKC involved in O2- production in PMNLs, and (c) phorbol myristate acetate (PMA) that binds and stimulates PKC. Insulin caused a dose- and time-dependent stimulation of H202 release by human PMNLs. The effect of insulin was blocked MA-10. The actions of insulin and PMA on H2O2 release were additive, whereas the actions of MA-5 and PMA were not. H7 partially inhibited the H2O2 production stimulated by insulin and completely inhibited MA-5 action. We conclude that insulin stimulates, in a dose- and time-related manner, the respiratory burst of human PMNLs. PKC activation can only partially account for the intracellular mechanisms involved in this process.

Detection by capillary electrophoresis of restriction fragment length polymorphism. Analysis of a polymerase chain reaction-amplified product of the DXS 164 locus in the dystrophin gene

Capillary electrophoresis (CE) was used to characterize restriction fragment length polymorphism (RFLP) in a polymerase chain reaction (PCR)-amplified product of a 740-base pairs DNA fragment from the DXS 164 locus of the dystrophin gene. The polymorphic alleles of 740 and 520/220 base pairs revealed by XmnI digestion were analysed from homozygous and heterozygous individuals by CE. Our studies show that extraction in phenol-chloroform may be useful in PCR-amplified product purification. Excellent separation was obtained in a short time. The data indicate that CE is suitable for genomic analysis such as carrier detection and prenatal diagnosis of X-linked recessive disorders after purification of PCR-amplified products.

PADGEM/GMP-140 expression on platelet membranes from homozygous beta thalassaemic patients

Thromboembolic events, which are associated with significant morbidity and mortality, occur in beta-thalassaemia. We studied the expression of the platelet selectin PADGEM/GMP-140 on intact cells from thalassaemic patients, as a marker of in vivo platelet activation. The mean of positive cells (%) was 38.143 +/- 20.65 in the patients versus 5.048 +/- 1.8 in the controls, n = 21, P < 0.001. No correlation was found between GMP-140 expression and splenectomy, platelet counts, plasma ferritin and natural coagulation inhibitors. Instead an indirect correlation was found between GMP-140 expression and HDL-cholesterol. Moreover platelet activation was directly correlated with pre-beta lipoproteins. Our data indicate that thalassaemic patients present an in vivo platelet activation, which possibly depends on the dyslipidaemia, which is now regarded as a frequent feature of this disease.

Hydrogen peroxide is an intermediate in the platelet activation cascade triggered by collagen, but not by thrombin

Human blood platelets produce oxidant species when stimulated by collagen and thrombin. The oxidative burst of platelets has been studied by cytofluorimetry taking advantage of the fluorogenic dye DCFH2-DA, which is taken up and deacetylated by platelets and then oxidized to the fluorescent derivative DCF. The oxidation of DCFH2 is induced by stimulation with collagen but not with thrombin and inhibited by external catalase. Catalase also inhibited the aggregation induced by collagen, but not that induced by thrombin. Aspirin and indomethacin inhibited the formation of the fluorochrome only when platelets were stimulated by thrombin. Externally added H2O2 increased the cytoplasmic calcium content as probed by the fluorescence of Indo-1. The present data suggest that collagen induces the production of H2O2, which in turn may stimulate the aggregation of platelets through a calcium mobilization. Instead the stimulation by thrombin does not require the intermediacy of H2O2.

Enhancement by growth hormone of phorbol diester-stimulated respiratory burst in human polymorphonuclear leukocytes

The oxidative metabolic burst of mononuclear and polymorphonuclear phagocytes can be stimulated to produce free oxygen radicals. Several substances can enhance this respiratory burst activity by a priming action: recently growth hormone (rat and porcine) was demonstrated to act as a priming agent on rat peritoneal and on porcine alveolar macrophages. In our study we wanted to verify whether also human GH had a similar priming action on homologous cells, in particular on polymorphonuclear leukocytes. To determine the oxidative activity of polymorphonuclear leukocytes, after stimulation with phorbol myristate acetate, a flow-cytometric assay was employed which registered the intracellular formation of highly fluorescent products as indicators for the intracellular formation of hydrogen peroxide. The incubation of phorbol myristate acetate-stimulated polymorphonuclear leukocytes with GH resulted in a time-dependent and dose-dependent increase in fluorescence, thus demonstrating that human GH enhances in vitro the oxidative metabolic burst of these cells. The action of GH appeared to be significant after 30 min of incubation, was maximal at 60 min, and decreased after 90 min. After one hour of incubation, the first significant variation of fluorescence appeared with GH at a concentration of 50 micrograms/l. The maximum effect was seen at 100 micrograms/l with no further increase. Specificity of GH action was demonstrated by the inhibition of its effect by the addition of monoclonal antibodies to GH.

Stimulated platelets release factor(s) affecting the in vitro response of human polymorphonuclear cells

The metabolic and functional responses of human polymorphonuclear cells (PMNs) to thrombin-activated platelet supernatants were studied. The incubation of PMNs with supernatants from stimulated platelets (SPS) caused a 50% decrease in both killing of Staphylococcus aureus and luminol-enhanced chemiluminescence (CL) by PMNs stimulated by opsonized-zymosan (OZ), Concanavalin A (Con A), or calcium ionophore A23187. The levels of PMN intracellular fluorescence measured by flow cytometry, using the fluorochrome dichlorofluorescein diacetate (DCF-DA), were considerably less in the presence of SPS than in resting platelet supernatants (RPS). No influence of platelet supernatant on O2 consumption and O2- generation by OZ-activated PMNs was observed. The incubation of PMNs with SPS caused a significant increase in the rate of chemotaxis and aggregation elicited by Con A, OZ, and phorbol myristate acetate (PMA). The supernatant from resting platelets did not show any of the above-reported effects. Platelets previously degranulated by thrombin were unable to inhibit CL when activated with agonists. Studies on the differential release of the granules by platelets showed that the CL-quenching activity paralleled the discharge of lysosomal content. The release of myeloperoxidase (MPO) from PMNs elicited by OZ was reduced in the presence of SPS. The platelet supernatant did not affect the MPO activity if PMNs were lysed with Triton X-100. The leakage of lactate dehydrogenase (LDH) from platelets was less than 3%, and no catalase or superoxide dismutase was released. This activity withstood lyophilization, but was destroyed by 10 min heating at 100 degrees C or by treatment with proteolytic enzymes.

Platelet lipid peroxidation in haemodialysis patients: effects of vitamin E supplementation

In haemodialysis patients, increased concentrations of malonyldialdehyde and decreased vitamin E content indicate lipid peroxidation in the platelets from oxidative damage. The same process has been described in red blood cells and in mononuclear cells in peripheral blood. However, platelet aggregation is within normal limits and does not change after treatment with vitamin E. On the other hand vitamin E supplementation reverts completely the biochemical abnormality of the platelets.

Treatment of acute idiopathic thrombocytopenic purpura (AITP): cooperative Italian study group results

A cooperative Italian study group on acute idiopathic thrombocytopenic purpura (AITP) has been designed to evaluate efficacy and safety of no treatment at the onset of the disease and sequential treatment with immunoglobulin and high dose steroid. One hundred thirty-eight patients with AITP entered in the trial. Eleven patients were treated before the end of the waiting period because of bleeding. One hundred twenty-seven (92%) received no treatment for the first 10 days of the disease, 65 patients (51.18%) recovered spontaneously, 62 patients were treated with immunoglobulin, and 52 (83.8%) of them responded positively but only 36 (58.06%) permanently. There was no statistical difference between the results obtained with 400 mg/kg for 5 days versus 200 mg/kg. Twenty-four patients were treated with high doses of steroids, 20 (83.3%) with positive response, and 10 (41.66%) were permanently cured. Four (3.14%) of the patients enrolled in the protocol still had active disease at the end of treatment, and 10 relapsed within 4 months after the end of the treatment.

A surface NAD-glycohydrolase of human platelets may influence their aggregation

Human platelets may hydrolyze externally added NAD+ yielding ADPR and nicotinamide. The extent of hydrolysis is significantly higher when the platelets are stimulated. The presence of external NAD+ strongly inhibits the aggregation induced by every agonist used. It seems that adenosine or ADPR itself generated by NAD+ hydrolysis may be responsible for the inhibition of aggregation. Evidence is given that some of the NAD+ hydrolysis product is taken up by stimulated platelets.

Vitamin E consumption by human blood platelets activated by latex particles

Human blood platelet activation elicited by latex particles is associated to a 30% decrease in the cellular content of vitamin E. The vitamin E consumption is inhibited by the addition of catalase (500 U/ml) and azide (1 mM), but it is not affected by potassium cyanide (1 mM). It may be proposed that the challenge of platelets with particulate stimuli causes generation of oxygen reduction products, which leads to vitamin E depletion.

Isotachophoresis as a useful tool for monitoring neurological complications of acute leukaemia in children

Cerebrospinal fluid proteins from 42 children with acute lymphoblastic leukaemia were analysed by isotachophoresis. The isotachopherograms of cerebrospinal fluid taken from patients undergoing central nervous system prophylaxis with neurological complications showed an increase of several peaks (albumin, prealbumin, and an unidentified peak), and changes in the globulin zone, compared with those from patients who had completed central nervous system prophylaxis for at least six months. The most striking finding was that these alterations were not associated with any other biochemical changes in the cerebrospinal fluid, as assayed by routine analysis. Isotachophoresis may be useful in the monitoring of therapy in children affected with acute lymphoblastic leukaemia.

Hydrogen peroxide has a role in the aggregation of human platelets

The aggregation of platelets induced by soluble and particulate stimuli is enhanced by the addition of minute amounts of H2O2. Externally added catalase strongly inhibits the aggregation induced by particulate stimuli and by phorbol myristate acetate (PMA). The addition of aminotriazole to stimulated platelets causes a significant inhibition of intracellular catalase. This indicates the formation of H2O2 inside the platelets during activation. No effects were observed when the platelets were stimulated by the ionophore A23187.

Ventricular thrombosis during permanent endocardial pacing in a pediatric patient with hemorrheological disorders

Thrombosis in the right atrium or ventricle is a rare complication of permanent endocardial pacing in adults. To the best of our knowledge, this complication has not been previously reported at all in the pediatric age group. We report on a case of a 7-year-old boy who had large left ventricular thrombi that occurred during permanent endocardial electrical stimulation. Subsequent pulmonary emboli complicated congestive heart failure in this patient. As a diagnostic approach, echocardiography and pulmonary perfusion scintigraphy were used. We comment on possible causes of this serious complication and suggest hemorrheological and platelet activation studies in patients with permanent endocardial pacing.

Photodynamic damage induced by bilirubin on human platelets: possible relevance to newborn pathology

Several reports have appeared showing the possibility of bilirubin-sensitized photodamage. We have extended these observations to platelets. In the presence of 300 microM bilirubin the in vitro irradiation of isolated platelets or platelet-rich plasmas with visible light induced significant lysis as determined by the release of lactate dehydrogenase (LDH). The extent of LDH release was a function of irradiation time, being about 20% after 2 h of irradiation. A loss membrane-bound ATPase activity was also observed at earlier times, indicating that membrane damage was preliminary to the lytic effect. The release of beta-thromboglobulin, induced by close cell-to-cell contact, was lower in bilirubin- and light-treated platelets with respect to controls. Our results suggest that bilirubin may act as a photodynamic agent producing some damage on human blood platelets.

Intravenous pulse methylprednisolone in chronic idiopathic thrombocytopenia

Two children with chronic idiopathic thrombocytopenic purpura unresponsive to either standard corticosteroid treatment or high dose intravenous gammaglobulin, or both, were treated with intravenous methylprednisolone (15 mg/kg/day) given in pulses over three consecutive days. Both children showed a positive response and are still in remission after three months.

Interaction of terbium with human platelets

The effect of terbium on platelets has been studied by aggregation experiments and by fluorescence measurements. TbCl3 does not substitute for CaCl2 in the aggregation of platelets induced by ADP, but it may even inhibit, probably by a competition mechanism. It was impossible to observe a sensitized emission of Tb3+ in the presence of platelets. Instead the lanthanide, like Ca2+, significantly increases the aggregation of platelets induced by A23187. The fluorescence yield of this compound is greater in the presence of platelets than in buffer alone. Energy transfer appears to take place from the aromatic amino acids of the platelet membrane to the bound ionophore.

Opsonized-zymosan induces a respiratory burst in human blood platelets

Opsonized-zymosan-stimulated polymorphonuclear cells show a cyanide-insensitive oxygen consumption. We have investigated whether opsonized-zymosan could induce similar metabolic change in human blood platelets. Preparation of intact human blood platelets, obtained by separation through a Ficoll layer (23% w/v) were challenged with opsonized-zymosan. The polymorphonuclear cell contamination was less than 1/10(8) platelets. The opsonized-zymosan-stimulated platelets showed an increase of oxygen consumption. The mean of oxygen burst measured by a polarographic method with a Clark electrode was 11 nmole/10(9) platelets/min (S.E.M. 4; n = 15). The duration of the burst was 2 min. Unstimulated platelets did not show the oxygen burst. The inhibitors of respiratory chain and prostaglandin synthesis completely abolished the oxygen consumption by opsonized-zymosan-stimulated platelets. The simultaneous addition of NADH (1 mM) and opsonized-zymosan induced a burst of oxygen consumption, which occurred after a variable lag phase (10-12 min) from the stimulation, also in the presence of inhibitors. This burst, which lasted about 1 min, amounted to 10 nmole/10(9) platelets/min (S.E.M. 2; n = 15) and it was higher in the presence of NAN3, a catalase inhibitor. Zymosan treated with hydrazine or heated plasma (56 degrees C) did not cause increased oxygen consumption. Inulin or inulin-treated serum did not stimulate platelets. In these experimental conditions some NADH disappeared, as shown by isotachophoresis. The results demonstrated that an immunological stimulus may activate a membrane-linked cyanide-insensitive oxygen metabolizing system.

Superoxide-dependent chemotactic activity for PMNs derived from opsonized zymosan-stimulated human platelets

Previous studies have shown that platelets exhibit a H2O2 producing, NADH-dependent system that is activated by interaction with particulate material. Current evidence suggests that this system could be critically involved in th generation of chemotactic factor(s). In the present studies, chemotactic activity for polymorphonuclear leukocytes of supernatants derived from zymosan-stimulated human platelets has been evaluated using an agarose gel technique. Supernatants of opsonized zymosan-stimulated platelets showed significant chemotactic activity (migration index = 300 +/- 50), in comparison with supernatants prepared from platelet suspensions stimulated with nonopsonized-zymosan (migration index = 10 +/- 15) or resting platelet supernatants (migration index = 15 +/- 15). Furthermore, a marked increase in chemotactic activity of the opsonized zymosan-treated platelet supernatants was demonstrated after the addition of NADH (migration index = 525 +/- 100). The inclusion of specific inhibitors of the cycloxygenase and lipoxygenase pathways resulted in a marked reduction of chemotactic activity, which was restored in the presence of NADH. Further, the addition of superoxide dismutase completely abolished the chemotactic response induced by NADH. These data suggest that platelets are the source of chemotactic factor(s) derived from the activation of a superoxide generating system.

Hydrogen peroxide release from human blood platelets

The release of hydrogen peroxide from human blood platelets after stimulation with particulate membrane-perturbing agents has been determined by fluorescence using scopoletin as the detecting agent. Platelet suspensions containing less than 1 polymorphonuclear leukocyte/10(8) platelets showed a significant release of hydrogen peroxide (6.11 nmol/10(9) platelets per 20 min, S.D., 0.26, n = 9) after addition of zymosan or latex particles, compared to unstimulated platelets. The release of hydrogen peroxide was only observed when the scopoletin was added to the platelet suspensions during the stimulation. Any attempt to determine hydrogen peroxide release in the supernatant at the end of the incubation with zymosan or latex failed. A NADH-dependent production of hydrogen peroxide was observed by measuring the difference of oxygen uptake in the presence and absence of catalase (500 units), which was not inhibited by potassium cyanide (1 mM). By this method the NADH-dependent cyanide-insensitive peroxide production and release was 6.0 nmol/10(9) platelets per 20 min from resting platelets (S.D., 2, n = 6) vs 15 nmol/10(9) platelets per 20 min from stimulated platelets (S.D., 2, n = 6).

The in vitro inhibitory effect on thrombin by 2,3-diphosphoglycerate

Thrombin incubated with 2,3-diphosphoglycerate (150 nmol 2,3-DPG/1 NIH thrombin unit) lost up to 70% of its clotting activity, whereas the esterase activity remained unchanged. No fibrinopeptide release by thrombin was observed in the presence of 2,3-DPG. The fibrin polymerization was normal. By chromatography on Amberlite IRC-50, alpha-thrombin was eluted at pH 8.0. In presence of 2,3-DPG, alpha-thrombin was not eluted. Likely, 2,3-DPG can interfere with thrombin.

[Blood platelet oxygen consumption in pituitary dwarfs (author's transl)]

Oxygen consumption in blood platelets of 14 pituitary dwarfs aged from 2 to 8 years was investigated before and after a 2 months' treatment with growth hormone (GH). No significant difference was found between dwarfs and control subjects in respect of basal platelet oxygen uptake (4.0 +/- 3.8 mmol O2/10(9) platelets/min in dwarfs as against 6.4 +/- 4.1 in controls), but the abrupt increase in oxygen consumption induced by thrombin was significantly reduced in dwarfs (4.3 +/- 4.1) as compared with controls (12.3 +/- 7.6; p less than 0.01). During GH treatment, however, the dwarfs' response to thrombin stimulation was similar to that of controls. Since dwarfs had normal platelet malonyldialdehyde production, it is likely that the mitochondrial component of thrombin-induced high oxygen consumption was deficient. These results suggest that blood platelets may contribute to the protective effect of GH deficiency against atherosclerosis.