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Biomedical subjects

H Wadenvik

Publications and source records attributed to H Wadenvik.

At least 37 records · Page 2Linked to original sources
PubMed1998

Plasma thrombopoietin levels in thrombocytopenic states: implication for a regulatory role of bone marrow megakaryocytes.

To evaluate the diagnostic value of thrombopoietin (TPO, c-mpl ligand) measurements, and clarify the regulatory mechanisms of TPO in normal and in thrombocytopenic conditions, the plasma TPO concentration was determined in normal individuals (n = 20), umbilical cord blood (n = 40), chronic idiopathic thrombocytopenic purpura (ITP; n = 16), in severe aplastic anaemia (SAA; n = 3), chemotherapy-induced bone marrow hypoplasia (n = 10), myelodysplastic syndrome (MDS; n = 11), and sequentially during peripheral blood progenitor cell transplantation (n = 7). A commercially available ELISA and EDTA-plasma samples were used for the analysis. The plasma TPO concentration in the normals and umbilical cord blood were 52 +/- 12 pg/ml and 66 +/- 12 pg/ml, respectively. The corresponding values in patients with SAA and chemotherapy-induced bone marrow hypoplasia were 1514 +/- 336 pg/ml and 1950 +/- 1684 pg/ml, respectively, and the TPO concentration, measured sequentially after myeloablative chemotherapy and peripheral blood progenitor cell transplantation, was inversely related to the platelet count. In contrast, the plasma TPO recorded in patients with ITP (64 +/- 20 pg/ml) and MDS (68 +/- 23 pg/ml) were only slightly higher than normal levels. In conclusion, TPO levels were significantly elevated in patients in which bone marrow megakaryocytes and platelets in circulation were markedly reduced, whereas TPO levels were normal in ITP patients, and only slightly increased in the MDS patients. These latter patients displayed a preserved number of megakaryocytes in bone marrow biopsies. Our data support the suggestion that megakaryocyte mass affects the plasma TPO concentration. In thrombocytopenic patients a substantially increased plasma TPO implies deficient megakaryocyte numbers. However, TPO measurements do not distinguish between ITP and thrombocytopenia due to dysmegakaryopoiesis, as seen in MDS patients.

Adolescent↗
PubMed1998

Cytokine release during long-term extracorporeal circulation in an experimental model.

The objective of this study was to determine the degree of leukocyte activation, as measured by cytokine release, in circulating blood during experimental extracorporeal circulation. Complete in vitro extracorporeal membrane oxygenation (ECMO) circuits were used, and 9 experiments were performed. Whole blood stored at 37 degrees C was used as the control. Blood samples were withdrawn before the start of perfusion and at 24 h of perfusion. Statistically significant releases of interleukin (IL)-1beta, IL-8, and IL-1 receptor antagonist were observed in the perfusion circuits compared to both the control blood and baseline values. Also, increases in plasma tumor necrosis factor (TNF)alpha and IL-6 were seen after 24 h of perfusion although these changes did not reach statistical significance. These results indicate that extracorporeal circulation induced leukocyte activation and cytokine release. These reactions might, as an additional trauma, deteriorate the situation in an already severely ill patient. A search for methods to counteract this untoward activation seems warranted.

Adult↗
PubMed1998

Plasma erythropoietin by high-detectability immunoradiometric assay in untreated and treated patients with polycythaemia vera and essential thrombocythaemia.

By using an immunoradiometric method with a stated detection limit of < or =1 IU/l (stated normal reference limit in adults 3.7-16 IU/l) we determined EDTA-plasma erythropoietin (EPO) in 58 patients with polycythaemia vera (PV) and 49 patients with essential thrombocythaemia (ET). At the time of blood sampling, 20 of the PV patients were newly diagnosed and untreated, 23 were treated by phlebotomy only, and 30 also received myelosuppressive treatment (with 32P, hydroxyurea or alpha-interferon). Of the ET patients 24 were untreated and 28 received myelosuppressive therapy. For comparison plasma EPO was also determined in 10 patients with pseudopolycythaemia (PP). In this latter group the results for plasma EPO agreed well with the cited normal reference limits. The majority of untreated PV patients (12/20) had undetectable plasma EPO concentration, and the remainder all had values below the lower normal reference limit. Plasma EPO in PV was not significantly influenced by phlebotomy therapy. Twelve of the 24 untreated ET patients (50%) had plasma EPO values below the reference interval (undetectable in 2 patients). The mean EPO concentration was significantly lower in PV patients receiving phlebotomy therapy than in patients with untreated ET. In the total material of PV and ET treated with myelosuppressive agents the PV patients showed significantly lower values for EPO concentration than did patients with ET. The present results support the view that EPO measurements by high-detectability methods are diagnostically useful and should be included in the panel of new criteria for the diagnosis of PV.

Adult↗
PubMed1998

Impact of endogenous thrombopoietin levels on the differential diagnosis of essential thrombocythaemia and reactive thrombocytosis.

By using the newly commercialized Quantikine human TPO immunoassay, plasma thrombopoietin (TPO) concentrations were measured in 12 patients with essential thrombocythaemia (ET), 13 patients with reactive thrombocytosis (RT) and 11 healthy volunteers. For the healthy volunteers the mean plasma TPO concentration was 21.1+/-11.0 pg/ml. The mean plasma TPO concentration in the group of RT was slightly lower (16.4+/-8.6 pg/ml) but did not differ significantly from the control group. The mean plasma TPO concentration in ET patients (44.1+/-45.2 pg/ml) was significantly (p<0.05) higher than the mean for RT patients, but did not differ statistically from the mean of healthy volunteers. These data suggest a defective clearance of plasma TPO in patients with ET.

Adult↗
PubMed1998

Platelet proteins as autoantibody targets in idiopathic thrombocytopenic purpura.

Idiopathic thrombocytopenic purpura (ITP), caused by autoantibodies directed against certain platelet antigens, is the most common entity of the immune thrombocytopenias. ITP is an acquired disorder and can affect both children and adults. However, the clinical syndromes of ITP are distinct between children and adults. Childhood (acute) ITP characteristically is acute in onset, occurs within 1-2 weeks of an infection, usually of viral origin, resolves spontaneously within 6 months. Adult (chronic) ITP has an insidious onset and rarely resolves spontaneously. Over the last decade considerable new information has accumulated as to the pathophysiological mechanisms of immune thrombocytopenias. In addition, most of the knowledge on this disorder has been obtained from studies of adult patients with chronic ITP. The present work gives an updated overview of the platelet autoantigens and the molecular immunological reactions in ITP.

Acute Disease↗
PubMed1998

The effect of albumin priming solution on platelet activation during experimental long-term perfusion.

The objective of this study was to evaluate the effect of albumin priming on platelet consumption and activation during long-term perfusion. Two identical in vitro extracorporeal membrane oxygenation circuits were used; one was primed with Ringer's solution containing human serum albumin, the other with Ringer's solution only. Fresh heparinized human blood was pooled, divided between the two systems and circulated for 24 h at 37 degrees C. Platelet count, plasma concentration of betathromboglobulin (BTG), platelet membrane density of glycoprotein (GP) Ib and of GPIIb/IIIa were assayed before the start and at 0.5, 1, 3, 12 and 24 h of perfusion. In total, seven experiments were performed. We found that during the first hour of perfusion, slightly higher platelet counts (p = 0.058) and lower BTG values (p = 0.0005) were observed in the circuits primed with albumin, compared to the control circuits. No statistically significant differences were observed for the platelet membrane expression of GPIb and GPIIb/IIIa. We conclude that albumin priming appears to transiently prevent platelet consumption and activation during long-term perfusion.

Extracorporeal Membrane Oxygenation↗
PubMed1998

The influence of a serine protease inhibitor, nafamostat mesilate, on plasma coagulation, and platelet activation during experimental Extracorporeal Life Support (ECLS).

INTRODUCTION: During extracorporeal circulation the contact between blood and the artificial surface of the circuit induces several changes in the hemostatic system. The objective of the present study was to assess the effect of a serine protease inhibitor--Nafamostat mesilate (FUT-175)--on coagulation and on platelets during experimental extracorporeal circulation. METHODS: Two identical Extra Corporeal Life Support (ECLS) circuits were primed with fresh, heparinized human blood and circulated for 24 h. FUT-175 was added to one of the paired circuits and the other was used as a control. The following FUT-175 concentrations were employed: (1) 7.1 mg/l/h, (2) 14.2 mg/l/h, (3) 14.2 mg/l/h + 85.5 mg given as an initial bolus, (4) 28.5 mg/l/h + 171 mg given as an initial bolus. Blood samples were collected from the circuits before the start of the perfusion and at 0.5, 1, 3, 12, and 24 h of perfusion, and analysed for platelet count, plasma betathromboglobulin (beta-TG), platelet membrane glycoprotein (GP) Ib and GPIIb/IIIa expression, thrombin/antithrombin III complex (TAT), prothrombin fragment 1+2 (F1+2), fibrinogen, D-dimer, and plasminogen activator inhibitor 1 activity (PAI-1). RESULTS: Significantly higher platelet membrane GPIb expression and lower plasma beta-thromboglobulin levels were observed in the circuits holding FUT-175, suggesting a lower degree of platelet activation. Also, a reduced activation of the coagulation system was observed in the "FUT-circuits", as reflected by the levels of F1+2 and TAT, and the PAI-1 activity that was rapidly inactivated. CONCLUSION: FUT-175 reduces the activation of platelets and plasma coagulation in an in vitro ECLS model.

Anticoagulants↗
PubMed1997

Multiple quinine-dependent antibodies in a patient with episodic thrombocytopenia, neutropenia, lymphocytopenia, and granulomatous hepatitis.

A 58-year-old man experienced episodes of fever, vomiting, and diarrhea over a 2-year period. The laboratory evaluation during these attacks consistently disclosed thrombocytopenia, leukopenia, and elevated liver enzymes. A liver biopsy performed at one of these attacks showed a typical picture of granulomatous hepatitis. In retrospect, all episodes seemed to be associated with the ingestion of quinine. Indeed, such a correlation was established by a challenge with quinine. By using flow cytometry, quinine-dependent IgG antibodies to platelets were detected in the patient serum. By a two-color flow cytometric assay, the patient serum was also found to hold quinine-dependent antibodies specific for neutrophils, T lymphocytes, and B lymphocytes. Moreover, serum absorbed with neutrophils in the presence of quinine continued to react with platelets, T lymphocytes, and B lymphocytes; serum that was absorbed with mononuclear cells continued to react with neutrophils and platelets. These experiments indicated that the antigen targets were different on platelets, neutrophils, and lymphocytes. Further, the patient serum in the presence of quinine immunoprecipitated surface-labeled platelet proteins with electrophoretic mobilities closely resembling those of glycoprotein (GP) Ib/IX and GPIIb/IIIa. By a modified monoclonal antibody-specific immobilization of platelet antigens assay, the patient serum in the presence of quinine reacted with platelet GPIb/IX and GPIIb/IIIa. Also, the patient serum in the presence of quinine immunoprecipitated an uncharacterized 15-kD double-band from surface-labeled granulocyte proteins. We conclude that our patient's thrombocytopenia, neutropenia, and lymphocytopenia were caused by quinine-dependent antibodies and that these antibodies recognized cell lineage-specific epitopes.

Antibodies↗
PubMed1997

Immunoglobulins targeting both GPIIb/IIIa and GPIb/IX in chronic idiopathic thrombocytopenic purpura (ITP): evidence for at least two different IgG antibodies.

Antiplatelet antibodies in chronic idiopathic thrombocytopenic purpura (ITP) mainly target glycoprotein (GP) IIb/IIIa and GPIb/IX. Previous studies, employing modern antigen-specific assays, indicate that serum reactive with both GPIIb/IIIa and GPIb/IX is not an uncommon finding in chronic ITP. However, the mechanism behind this dual reactivity remains unclear. We studied sera from 72 patients with chronic ITP using modified GPIIb/IIIa- and GPIb/IX-specific MAIPA assays. Among the 34 positive sera, seven showed strong reactivity against both GPIIb/IIIa and GPIb/IX. These seven dual reactive ITP sera were further analysed by absorption studies. It was found that sera absorbed with immobilized GPIb/IX lost nearly all serum IgG specific for GPIb/IX but fully retained the IgG specific for GPIIb/IIIa. Conversely, sera absorbed with immobilized GPIIb/IIIa retained their reactivity only with GPIb/IX. These findings demonstrate that ITP sera, reactive with both GPIIb/IIIa and GPIb/IX, contain at least two different IgG antibody populations, each reactive with only one of the GP complexes.

Adolescent↗
PubMed1996

Light chain-restricted autoantibodies in chronic idiopathic thrombocytopenic purpura, but no evidence for circulating clone B-lymphocytes.

In chronic idiopathic thrombocytopenic purpura (ITP) platelet destruction is caused by antibodies directed against platelet membrane glycoproteins (GP), and the predominant autoantigens are known to be GPIb/IX and GPIIb/IIIa. In a recent study we reported that these antibodies frequently had a restricted light chain phenotype, thereby supporting a clonal origin. Similar findings and the presence of clonal B-cell populations in immune thrombocytopenias have been reported by others. In the present study we further explored the hypothesis of clonal B-cell expansions in chronic ITP. Twenty patients with chronic ITP were investigated. Antibodies were detected with an ELISA (MAIPA) specific for GPIb/IX and GPIIb/IIIa; circulating clonal B lymphocytes were assessed by flow-cytometric (FACS) clonal-excess analysis and by analyzing Ig-gene rearrangements (CDR3) with the PCR technique. Nine patients displayed a GP-specific antibody restricted to either kappa or lambda phenotype. However, FACS analysis and Ig-gene rearrangement studies did not disclose any circulating clonal B-cell population. Considering the sensitivity of the FACs analysis and Ig-gene rearrangement for detection of clonal B-cell populations, the hypothesis of clonally derived autoantibodies in ITP is still valid. Most probably, the clonal B-cell expansion responsible for the production of autoantibodies in ITP, if present, is below the detection limit for the techniques employed.

Adolescent↗
PubMed1996

Nitric oxide in the oxygenator sweep gas reduces platelet activation during experimental perfusion.

BACKGROUND: Hemorrhage is a major complication experienced in 10% to 35% of neonates treated with extracorporeal life support (ECLS). The increased bleeding tendency is partly due to an ECLS-induced thrombocytopenia and impaired platelet function. In the present study, we evaluated the effect of nitric oxide on the ECLS-induced platelet consumption and activation. METHODS: Two identical in vitro ECLS circuits were primed with fresh, heparin-treated human blood and circulated for 24 hours. Nitric oxide (15, 40, or 77 ppm) was added to one of the oxygenators in each pair. Eight paired experiments were performed. Platelet count, plasma beta-thromboglobulin, platelet serotonin content, plasma nitrate, plasma cyclic guanosine monophosphate, and platelet membrane glycoprotein Ib were assayed before the start and at 0.5, 1, 3, 12, and 24 hours of perfusion. RESULTS: Plasma nitrate and plasma cyclic guanosine monophosphate levels were significantly higher in the nitric oxide circuits than in the control circuits (p < 0.01). Higher platelet counts (p < 0.01) and lower beta-thromboglobulin levels (p < 0.01) were observed in the nitric oxide circuits compared with the control circuits. However, no significant differences in platelet serotonin content or platelet membrane glycoprotein Ib density were noted between the circuits. CONCLUSIONS: Nitric oxide probably reduces platelet consumption and platelet activation during ECLS.

Analysis of Variance↗
PubMed1996

Blood group A antigen expression in platelets is prominently associated with glycoprotein Ib and IIb. Evidence for an A1/A2 difference.

Blood group ABH antigens are associated with platelets as intrinsic determinants and extrinsically adsorbed antigens, and exist both on glycosphingolipids and on glycoproteins (GPs). We now provide direct evidence that the blood group ABH antigens are prominently associated with platelet GPIb and GPIIb. By immunoprecipitation, a murine monoclonal anti-A antibody precipitated surface-biotin-labelled blood group A1 platelet membrane proteins with electrophoretic characteristics identical to those of GPIb/IX and GPIIb/IIIa. By immunoblotting of SDS-PAGE separated blood group A1 platelet proteins the monoclonal anti-A antibody bound to proteins with electrophoretic characteristics identical to those of GPIb and GPIIb. When immunoaffinity purified GPIb/IX and GPIIb/IIIa, derived from blood group O, A1 and A2 platelets, were employed for immunoblotting, GPIb and GPIIb only from A1 platelets bound the monoclonal anti-A antibody. By ELISA, wherein monoclonal antibodies specific for GPIb (APl) and the GPIIb/IIIa complex (AP2) were used to capture and hold antigens from platelet lysate, human anti-A antibodies reacted with these proteins derived from blood group A1 platelets; proteins from blood group A2, O and B platelets showed no reactivity. These results indicate that blood group A antigen is associated with GPIb and GPIIb derived from blood group A1 but not A2 platelets.

ABO Blood-Group System↗
PubMed1996

Evidence for an expression of blood group A antigen on platelet glycoproteins IV and V.

Blood group ABO antigens are known to be carried by several platelet glycoproteins (GP), e.g. GPIb, GPIIa, GPIIb, GPIIa and PECAM. Beside these proteins, we recently observed that blood group A antigen was also expressed on some other uncharacterized platelet proteins (70-90 kDa) having electrophoretic mobilities closely resembling those of GPIV and GPV. These findings prompted us further to characterize these latter ABO-expressing platelet proteins. By antigen capture ELISA, wherein the monoclonal antibodies (mAbs) CLB-IVC7 and CLB-SWI6 were used to hold the corresponding antigens GPIV and GPV, human anti-A specifically bound to these proteins derived from A1-platelets; neither GPIV nor GPV derived from A2-, B- or O-platelets bound anti-A. In a Western blot assay using immunoprecipitated GPIV and GPV as antigens, mAb anti-A immunostained GPIV and GPV precipitated from A1, but not from A2 and O platelets. These results conclusively demonstrate that blood group A antigen is expressed on platelet GPIV and GPV.

ABO Blood-Group System↗
PubMed1996

Flow cytometric analysis of megakaryocyte ploidy in chronic myeloproliferative disorders and reactive thrombocytosis.

Megakaryocyte (MK) ploidy patterns were analysed by flow cytometry in 29 newly diagnosed and previously untreated patients with chronic myeloproliferative disorders (MPD) and concomitant thrombocytosis, in 9 patients with reactive thrombocytosis (RT) and in 12 healthy individuals. Unfractionated bone marrow from routine aspirates was used. MKs were identified with a fluorescein labelled monoclonal antibody specific for glycoprotein IIIa (GPIIIa) and DNA was stained with propidium iodide. For the 12 healthy volunteers the mean modal ploidy number was 16 N; the 9 patients with RT displayed an identical MK ploidy pattern. The frequency of MKs with a ploidy > or = 32 N was 45% among the patients with essential thrombocythaemia (ET) compared to 32% among the healthy volunteers (p < 0.001). MKs with ploidy number > or = 64 N, comprising approximately 13% of the total number of MKs, was a characteristic finding in the patients with ET. Similar findings were present in 8 patients with polycythaemia vera (PV). In patients with PV 34% and 6% of the MKs displayed ploidies > or = 32 N and > or = 64 N, respectively. In contrast, a distinct shift towards lower ploidy number, with 63% of MKs < or = 8 N, was found among the 4 patients with chronic myeloid leukaemia (CML). The present results indicate that by using flow cytometric analysis of MK ploidy distribution in patients with thrombocytosis, those with a reactive cause are likely to be discriminated from patients with myeloproliferative thrombocytosis, i.e. PV and ET on one hand and CML on the other hand. The distinction between ET and PV, however, has to be made on other grounds.

Adult↗
PubMed1996

Assessment of spleen size using gamma camera scintigraphy in newly diagnosed patients with essential thrombocythaemia and polycythaemia vera.

By using gamma camera imaging the spleen size was assessed in 18 consecutive patients with essential thrombocythaemia (ET) and in 18 consecutive patients with polycythaemia vera (PV). All ET and PV patients were newly diagnosed and had not received any myelosuppressive therapy prior to study. The spleen areas in both posterior and left lateral projections were determined. Eighteen consecutive patients with idiopathic thrombocytopenic purpura (ITP) served as a control group since by definition they do not present with splenic enlargement; in these latter subjects the mean posterior and left lateral splenic areas were almost identical (48 +/- 15 and 47 +/- 17 cm2, respectively). In comparison with this control group patients with ET and PC had significantly larger spleens. In both ET and in PV patients the left lateral spleen scan area exceeded the posterior one. Patients with PV had larger splenic areas in both projections than did patients with ET, but the differences were not statistically significant. Compared to the ITP patients it was found that at least 50% of the ET patients and at least 61% of the PV patients at diagnosis presented with splenomegaly.

Adult↗
PubMed1996

Genotyping of the platelet-specific alloantigen HPA-5 (Br(a)/Br(b)) using polymerase chain reaction with sequencespecific primers (PCR-SSP).

A DNA-based one-stage technique, polymerase chain reaction with sequence-specific primers (PCR-SSP) was developed for genotyping of the platelet specific alloantigen HPA-5 (Bra/Brb). Sequence-specific primers, matching the wild type and the point mutation responsible for the HPA-5 (Bra/Brb) phenotype, were constructed. Conjointly a fragment of the gene coding for glycoprotein (GP) IIIa was amplified as an internal control of the enzyme reaction. Using these HPA-5 (Bra/Brb) sequence-specific primers the correct fragment of the GPIa gene was amplified, as evidenced by the PCR product size, the restriction map and by the nucleotide sequence. This assay was applied on 187 Swedish blood donors; 157 individuals were found to have a homozygous HPA-5a (Bra/Brb) genotype and 30 individuals a heterozygous HPA-5a,b (Bra/Brb) genotype. None of the donors was found to display a homozygous HPA-5b (Bra/Brb) genotype. Thus, the (HPA-5b) Bra antigen frequency in this population will be approximately 16.0% with a gene frequency of 8.0%. It is concluded that this assay is an attractive technique for genotyping of the HPA-5 (Bra/Brb) alloantigens on genomic DNA. The technique can replace serological alloantigen typing, especially in cases where platelets and rare human alloantisera are not available.

Adult↗
PubMed1996

Platelet activation and degradation in an experimental extracorporeal system. A comparison between a silicone membrane and a hollow-fibre oxygenator.

Blood platelets are rapidly activated in contact with biomaterials and, therefore, can be used as markers of the biocompatibility of various components in an extracorporeal system. In the present work two different oxygenators, one membrane oxygenator (Avecor) and one hollow-fibre oxygenator ("Lilliput', Dideco) were compared. Complete in vitro extracorporeal membrane oxygenation circuits were perfused with fresh, heparinized human blood for 24 h. Eight experiments were performed with the hollow-fibre oxygenator and five experiments with the membrane oxygenator. Blood gases, electrolytes, glucose and haematocrit were kept within physiological limits. Platelet count, plasma concentration of beta-thromboglobulin, platelet serotonin content, platelet membrane glycoprotein lb and its degradation product glycocalicin, as well as plasma haemoglobin concentration were assayed. As regards most of these variables, significant differences in favour of the hollow-fibre oxygenator were observed.

Extracorporeal Membrane Oxygenation↗