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S Panzer

Publications and source records attributed to S Panzer.

At least 55 records · Page 3Linked to original sources
PubMed1999

Multiplex PCR reaction for the detection and identification of immunoglobulin kappa deleting element rearrangements in B-lineage leukaemias.

Immunoglobulin kappa (Igkappa) gene recombinations can be used - similarly to IgH rearrangements - as clonal markers in B-lineage leukaemias. Based on the extensive junctional diversity, these rearrangements represent valuable targets for the analysis of minimal residual disease (MRD). In order to provide a simple method for the rapid detection of leukaemia clone-specific kappa deleting element (Kde) mediated rearrangements, we developed a multiplex PCR reaction that is able to amplify the five most frequent rearrangements in one tube. Position of the amplimers were chosen to enable identification of the involved segments according to the size of the PCR product. This method was tested on 101 B-lineage leukaemias (71 childhood B-cell precursor acute lymphoblastic leukaemias (BCP ALL) and 30 chronic lymphocytic leukaemias (CLL)). 39 and 22 Kde rearrangements could be readily detected in 30 (44%) BCP ALL and 22 (56%) CLL, respectively. 36% of the Kde rearrangements in BCP ALL and 45% in CLL were intron recombination signal sequence (RSS)-Kde rearrangements. The other Kde rearrangements involved the Vkappa families: VkappaI in 36% and 50%, VkappaII in 32% and 16.7%, VkappaIII in 24% and 25%, and VkappaIV in 8% and 8.3% in BCP ALL and CLL, respectively. The sensitivity of the multiplex system was 10-2-10-3. We compared this multiplex PCR assay with multiple single PCR reactions using different sets of primer combinations. Thereby the number and types of rearrangements were confirmed in all cases. Clonality of rearrangements was proven by sequence analysis. Our data show that by this method clonal Kde rearrangements were rapidly detected and precisely identified.

Adult↗
PubMed1999

Male fetuses are particularly affected by maternal alloimmunization to D antigen.

BACKGROUND: It is hypothesized that male fetuses are more severely affected by fetomaternal alloimmunization to D antigen than female fetuses. STUDY DESIGN AND METHODS: One hundred four consecutive pregnancies with single D+ fetuses (51 males, 53 females) and maternal anti-D titers >16 were analyzed retrospectively. RESULT: Sixty fetuses (58%) received intrauterine transfusions. Male fetuses required more transfusions than females (5.0 vs. 2.0, p = 0.0001). At the initial transfusion, male fetuses had a lower gestational age (24.5 vs. 31.0 weeks, p = 0.0007), cord blood hemoglobin content (6.45 vs. 8.75 g/dL, p = 0.01), and hematocrit (19.8 vs. 26.8%, p = 0.004) than female fetuses. After adjustment for maternal gravidity, parity, and history of affected offspring, the odds ratio for development of hydrops by male fetuses was 13.1 (95% CI 2.69-63.6, p = 0.001). Perinatal mortality was higher in male (18%) fetuses than in female (6%) (adjusted odds ratio for males 3.38; 95% CI 0.59-19.46, p = 0.17). CONCLUSION: Male fetuses are particularly affected by maternal alloimmunization to D and require more intense antepartum surveillance than female fetuses.

Adult↗
PubMed1999

IgG titer, subclass, and light-chain phenotype of pregnancy-induced HPA-5b antibodies that cause or do not cause neonatal alloimmune thrombocytopenia.

BACKGROUND: The most common pregnancy-induced platelet-specific antibody is HPA-5b. Neonatal alloimmune thrombocytopenia that results from anti-HPA-5b may cause severe hemorrhage in only a few infants, but the sequelae for the affected children can be severe. It is therefore essential that infants at risk for neonatal alloimmune thrombocytopenia are identified. STUDY DESIGN AND METHODS: The IgG titer, subclass, and light-chain composition of pregnancy-induced anti-HPA-5b were determined by the monoclonal antibody-specific immobilization of platelet antigens assay. Sera were from 12 mothers, who among them had 16 pregnancies that resulted in an HPA-5-mismatched fetus (positive for HPA-5b). Eight mothers gave birth to an infant with a normal platelet count. Three maternal sera were obtained after delivery of a severely thrombocytopenic infant. Three alloimmunized women were followed repeatedly during the course of a subsequent pregnancy, again with an HPA-5-mismatched infant. RESULTS: There was no difference in the antibody titer or its subclass in mothers who had a thrombocytopenic child and the titer or subclass in mothers compared with those who had a child with a normal platelet count. All pregnancy-induced HPA-5b antibodies were of a predominant, lambda, light-chain type. The IgG subclass did not change during pregnancy. CONCLUSION: Neither the antibody titer nor the subclass composition predict the occurrence of thrombocytopenia in a newborn whose mother is alloimmunized against HPA-5b.

Antigens, Human Platelet↗
PubMed1999

Thrombopoietic cytokines and reversal of thrombocytopenia after liver transplantation.

OBJECTIVES: Thrombopoietin (TPO), the key regulator of platelet production, is mainly produced by the liver and reduced expression of TPO could cause thrombocytopenia in liver cirrhosis. Reversal of thrombocytopenia by orthotopic liver transplantation seems to be mediated through an increase in TPO plasma levels after transplantation, but other cytokines with thrombopoietic activity could augment the actions of TPO on post transplant platelet recovery. DESIGN: Measurement of thrombopoietic cytokines before and for 14 days post liver transplantation in a cohort of thrombocytopenic liver transplant patients. METHODS: TPO, interleukin-3 (IL-3), IL-6, and IL-11 plasma levels as well as peripheral platelet count were analysed in thrombocytopenic patients with liver disease undergoing orthotopic liver transplantation (17 patients) and followed for 14 days after the intervention. RESULTS: Before liver transplantation, TPO plasma levels were undetectable and IL-3, IL-6, and IL-11 levels were normal. Sixteen out of 17 patients showed a significant rise of TPO levels within 2 days after transplantation, with a peak between days 4 and 6, while IL-3 and IL-6 levels did not show a significant rise. IL-11 levels remained normal. Platelet counts were significantly higher than pretransplantation levels by day 14 post transplantation. CONCLUSION: Restitution of normal TPO production by liver replacement seems to be of key importance for reversal of thrombocytopenia in liver disease. The early acting thrombopoietic factor IL-3 and the late acting factors IL-6 and IL-11 do not play a major role for recovery of peripheral platelet count after orthotopic liver transplantation.

Analysis of Variance↗
PubMed1999

The proportion of reticulated platelets is higher in bone marrow than in peripheral blood in haematological patients.

Since the detection that platelets originate from megakaryocytes (MK), the site of megakaryocyte fragmentation has been disputed. Some authors have even postulated that platelets are solely produced in the lungs. Thus, we have directly measured platelet generation in the bone marrow (BM) by comparing the relative number of young RNA-containing, so-called reticulated platelets (%RP) in the BM and in the peripheral blood (PB). Two separate prospective, cross sectional trials have been conducted in patients routinely undergoing BM biopsies for diagnostic purposes. In the first part of the study 30 patients with stem cell or bone marrow transplantation were examined. The second part of the study was performed in 62 haematological patients visiting the outpatient's clinic. Median %RP were higher in BM than in PB (p <0.001). In the second part of the study the difference averaged 133% (interquartile range: 30-383%). There was a moderate correlation between %RP in BM and in PB (r = 0.67; p <0.001). The absolute number of RP in PB correlated weakly with the number of megakaryocytes (0.42; p = 0.001), which was due to a correlation between the platelet counts and the megakaryocyte counts (r = 0.55; p <0.001 in biopsies). Two patients with autoimmune antibodies against GPIIb/IIIa exhibited 10% and 16% RP in PB, and had 29% and 59% RP in BM, respectively. It is concluded that the relative number of RP is significantly higher in BM than in blood. This supports the notion that platelets are at least in part released from MK in the bone marrow, particularly in patients suffering from immune thrombocytopenia.

Antigens, Surface↗
PubMed1999

Effects of endotoxemia on thrombopoiesis in men.

BACKGROUND: Febrile conditions are often associated with increased platelet turnover and refractoriness to platelet transfusions, although several pyrogenic cytokines enhance thrombopoiesis. This study aimed to characterize the effects of experimental human endotoxemia on platelet turnover and thrombopoiesis. METHODS: Endotoxin (4 ng/kg) was infused into 30 healthy men to study the regulation of thrombopoiesis in systemic human inflammation. Platelet counts, plasma thrombopoietin (TPO) and glycocalicin levels, and reticulated platelets (RP) were measured to evaluate the effect of acute endotoxemia on thrombopoiesis. Ten subjects received pretreatment with 1000 mg aspirin po. to evaluate possible effects of aspirin on platelet turnover, and ten subjects received paracetamol to control for effects of antipyresis. RESULTS: Platelet counts dropped by about 15% (p <0.001) one hour after LPS infusion, began to recover at 24 h, and exceeded baseline values by 81% (CI: 5-12; p <0.001 ) at 7 days after LPS iv. Reticulated platelet counts increased from 1.62% (CI: 1.24-2.0) to a maximum of 2.39% (CI: 1.81-2.98; p = 0.003) at 6 h. TPO levels increased from baseline values of 10 A.U/ml (CI: 8.8-11.2) to 15.5 A.U/ml (CI: 13.6-17.3) at 24 h (p <0.001), whereas plasma glycocalicin was not changed (p >0.05). The number of circulating platelet-neutrophil aggregates increased more than 100% at 6 h (p <0.001). Neither aspirin nor paracetamol affected changes in any of the parameters measured. CONCLUSION: Low grade endotoxemia induces a rapid fall of platelet counts, which is followed by an early increase in reticulated platelets and TPO levels but not of glycocalicin levels. Finally peripheral platelet counts increase several days after LPS infusion.

Adult↗
PubMed1999

Oligoclonal immunoglobulin heavy-chain and T-cell receptor delta rearrangements persist in a recurrent acute lymphoblastic leukemia with one immunoglobulin kappa rearrangement as a clonal marker.

Acute lymphoblastic leukemias (ALLs) represent the clonal expansion of a lymphoid precursor cell. Therefore, all cells of an ALL should have identical antigen receptor gene rearrangements. In a patient with diploid ALL of the B-cell precursor immunophenotype, seven different clonal rearrangements of the immunoglobulin heavy-chain genes (IgH) were identified, implying the presence of oligoclonal populations. All of these rearrangements were only detectable after a modification of the polymerase chain reaction for the complementarity determining region of the IgH genes using V(H) gene framework 3 and (H) consensus primers. Sequence analysis showed that these rearrangements were completely unrelated to each other. Only two of these rearrangements were detectable by Southern blot analysis. Quantification and single-cell analysis confirmed the high frequency of these latter two rearrangements, as well as their presence in the same clonal population. The other rearrangements characterized less than 5% of the leukemic population. In addition, two T-cell receptor Vdelta2-Ddelta3 (TCRdelta) rearrangements were identified, both at a similar frequency. However, they were derived from different cells. An Igkappa rearrangement represented the only clonal marker in this leukemia. All of the Ig and TCRdelta rearrangements, with the exception of one IgH rearrangement, remained stable throughout the course of the disease. The persistence of such a great number of distinct IgH rearrangements at different quantities within the leukemic population and of the two biclonal TCRdelta rearrangements is compatible with the presence of a clonal disease that is defined by the Igkappa rearrangement.

Adolescent↗
PubMed1998

Screening for platelet auto-antibodies by flow cytometry and their evaluation by the MAIPA technique.

The determination of platelet antibodies assists in the diagnosis of immune thrombocytopenia. Among the various techniques which have been used two major ways for the determination of these antibodies have entered the routine use, determination of in vivo platelet bound total IgG, termed platelet-associated IgG, PAIgG, and that of specifically to particular platelet glycoproteins bound IgG, GP-IgG. The former has been found to be non-specific, and the evaluation of the latter is rather laborious. Furthermore, both require a large number of platelets. By flowcytometry, however, PAIgG can be determined even if platelet counts are very low. We therefore evaluated in 30 patients' samples if the flowcytometric determination of PAIgG can serve to screen for platelet antibodies. Positive samples subsequently are evaluated by a glycoprotein-specific detection technique (MAIPA). We show that in patients with suspected autoimmune thrombocytopenia (AITP) and in secondary AITP PAIgG is elevated in 83%. However, only 30% of patients' samples have detectable antibodies by the MAIPA technique. Based on the findings that by the MAIPA technique antibodies were only detectable in samples which had also elevated levels of PAIgG we consider the flowcytometric determination of PAIgG useful for screening, prior to the more laborious investigation by the MAIPA assay.

Antibodies, Monoclonal↗
PubMed1998

[Thrombocyte alloantigens].

A variety of alloantigens is expressed by the platelet membrane, whereby currently seventeen platelet specific antigen systems have been recognized. However, in Caucasoids immunization occurs most frequently against only four of these alloantigen systems. Alloimmunization can cause neonatal alloimmune thrombocytopenia, post-transfusion purpura and refractoriness for platelet transfusion. The importance of all alloantigen systems is evidenced by their discovery in association with neonatal alloimmune thrombocytopenia. The genetic polymorphisms of all systems is characterized by a single base mutation which induces a single amino acid substitution. This amino acid change is associated with a change of the tertiary structure of the glycoprotein, which results in high antigeneicity. As the molecular structure of thirteen systems has been elucidated, genotypings can be performed from genomic DNA by simple polymerase chain reactions. Thus, any equipped institution can provide typed donors to meet the clinical demands, without the need for specific antisera.

Antigens, Human Platelet↗
PubMed1998

Inherited platelet glycoprotein polymorphisms and a risk for coronary heart disease in young central Europeans.

Among central Europeans polymorphisms of GPIIIa, GPIb, GPIIb, and GPIa named human platelet antigen-1 (HPA-1), -2, -3, and -5 are the clinically most relevant systems in which alloimmunization occurs. These genetically determined polymorphisms of glycoproteins may render platelets sensible for plaque formation and thus could increase risk for coronary artery disease (CAD). We therefore determined gene frequencies of HPA-1, -2, -3, and -5 in European patients suffering from CAD (n = 92; median age, 46 years) or CAD accompanied by diabetes mellitus (DM) (n = 30; median age, 60 years, DM I/II, 5/25) and compared the data obtained with those in DM patients without CAD (n = 80; median age, 43 years; DM I/II, 53/27) and a control group (newborns, n = 906). Triglyceride and cholesterin levels as well as the percentage of smokers was significantly higher in the CAD group compared with the diabetics without DM (p < 0.005). No significant difference of the frequencies of any HPA-type between CAD patients with or without DM, diabetics, or controls could be detected. This was also true when evaluating a subgroup of patients aged 45 years or younger. To include a mutual influence of the described HPA-polymorphisms, we condensed the four HPA genotypes to joint glycoprotein variants. Again the same frequencies were found in patient groups and controls, when analyzing the five most common condensed joint glycoprotein variants. The analysis of the combined published studies shows that the pooled HPA-1 allele frequencies are identical in controls and CAD patients. Thus, no significant association between the polymorphisms of any of the studied HPA systems and the development of CAD can be found in central Europeans.

Adolescent↗
PubMed1998

The Tec29 tyrosine kinase is required during Drosophila embryogenesis and interacts with Src64 in ring canal development.

Tec29 encodes the only known Drosophila member of the Tec tyrosine kinases. By identifying the first mutations in Tec29 (formerly Src29A), we show that it is essential for head involution during embryogenesis and for ring canal development during oogenesis. Tec29 mutant egg chambers are defective in transfer of cytoplasm from the accessory nurse cells through the ring canals into the oocyte. Growth of the mutant ring canals is arrested, and they lack the strong phosphotyrosine localization seen in wild-type ring canals. Mutants lacking the Drosophila Src homolog Src64 show the same phenotype, and we show that Src64 is required for the localization of Tec29 to the ring canals. This interaction is similar to that between vertebrate Src and Tec kinases and suggests that Tec29 is an effector of Src64 that modifies ring canal components required for growth.

Actins↗
PubMed1998

Elevated numbers of reticulated platelets in hyperthyroidism: direct evidence for an increase of thrombopoiesis.

We studied thrombopoietic activity in hyperthyroidism by determination of reticulated platelet counts. At the time of hyperthyroidism 14/15 patients had higher reticulated platelets than after achievement of euthyroidism (P<0.001). There was no difference in peripheral platelet counts and mean platelet volumes at the time of hyperthyroidism when compared to euthyroidism. Three patients had pan- and auto-reactive platelet antibodies during hyperthyroidism. These antibodies were directed against GPIIb/IIIa in two patients and against GPIb/IX in one patient. Our findings provide direct evidence that hyperthyroidism is associated with increased platelet production, as reflected by an increase in reticulated platelets.

Adult↗
PubMed1998

Multiplex PCR for TCR delta rearrangements: a rapid and specific approach for the detection and identification of immature and mature rearrangements in ALL.

The preferential occurrence of immature T-cell receptor (TCR) delta rearrangements (i.e. incomplete Ddelta2-Ddelta3 and Vdelta2-Ddelta3) in B-cell precursor acute lymphoblastic leukaemia (BCP ALL) and of predominantly mature rearrangements (incomplete Ddelta2-Jdelta1, complete Vdelta1, Vdelta2, Vdelta3 to Jdelta1) in T-lineage ALL prompted us to establish two separate multiplex PCR systems for the identification of clonal TCRdelta rearrangements. PCR products of the expected size for the specific rearrangements were detectable from a dilution of 100-1000 clonal cells in 150000 polyclonal cells. Both multiplex PCR systems were used to analyse samples from 86 childhood BCPALLs and 30 T-lineage ALLs. The results of the multiplex PCRs were controlled by standard PCR analyses for the individual rearrangements and Southern blots, which were identical. Only immature TCRdelta rearrangements were detected in BCP ALL (59%), whereas no rearrangement was found in the remaining BCP leukaemias, thus confirming the exclusive presence of immature TCRdelta rearrangements in B-lineage cells. 50% of the T-lineage ALLs contained mature rearrangements, but no immature rearrangements were found. These two multiplex PCR techniques appear to be reliable and fast aids in the analysis of clonal TCRdelta rearrangements in ALL.

Blotting, Southern↗
PubMed1998

Direct evidence for an increase in thrombopoiesis after liver transplantation.

BACKGROUND: In advanced liver cirrhosis, thrombocytopenia results from 'hypersplenism' due to increased platelet sequestration and platelet 'pooling' in the enlarged spleen and/or from reduced platelet production in the bone marrow. We sought to differentiate between these two mechanisms by studying thrombopoiesis before and after orthotopic liver transplantation by the determination of reticulated platelets, direct indicators for the thrombopoietic activity in the bone marrow. METHODS: Reticulated platelets, peripheral platelet counts, mean platelet volumes and platelet-reactive antibodies were determined in 15 patients suffering from advanced liver cirrhosis before and during an observation period of 14 days after orthotopic liver transplantation (OLT). Thrombopoietin levels of ten patients were determined before transplantation and consecutively for 14 days after surgery. RESULTS: All patients except one were thrombocytopenic before transplantation (median count 94 x 10(9) L-1, range 69-114 x 10(9) L-1). Although levels of reticulated platelets rose 2 days after surgery from baseline values of 1.0% (range 0.2-1.6%) to peak values of 4.6% (range 1.7-17.9%, P < 0.05) on day 6, platelet counts declined during the first 5 days after transplantation. When peripheral platelet counts increased to the normal range (median day 11, range day 8-33), reticulated platelets were again at pretransplant levels. Thrombopoietin levels before OLT were within the normal range (< 85 pg mL-1). On day 5 post surgery, a maximum increase of 5.8-fold (range 2.2- to 28-fold) over baseline values was observed. Mean platelet volume did not show any significant deviation from the baseline values and platelet antibodies could not be detected during the observation period. CONCLUSION: Our findings provide direct evidence for an increase in de novo platelet production after orthotopic liver transplantation. As the elevation of reticulated platelets precedes platelet recovery, it could serve as an early indicator to predict thrombopoiesis as a result of reconstituted liver function.

Adult↗
PubMed1998

Report on the 1997 International Society of Blood Transfusion Workshop for Genotyping of Platelet Alloantigens. Platelet and Granulocyte Workshop ISBT.

The results from the 1997 International human platelet antigen- (HPA-) genotyping workshop are reported. Seventeen institutions participated to genotype for HPA polymorphisms of seven DNA samples. Most investigators used the polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) and PCR-sequence specific priming (SSP). A few participants applied both methods to confirm their results. All participants reported results for HPA-1, -2, -3 and -5 allotyping, while HPA-4 was determined in 12 and HPA-6 in nine laboratories, respectively. For HPA-1 to -6 there were 19 deviations from the consensus result. These deviations were not associated with any particular technique or allotype. Most frequently, however, deviation were reported for HPA-5 typing. These results were discussed at a meeting at the Joint Congress of the ISBT and the Deutsche Gesellschaft für Transfusionsmedizin und Immunhämatologie in Frankfurt, Germany, in September 1997. Based on the results and the comments, further workshops for HPA-allotyping are mandatory for quality assurance.

Antigens, Human Platelet↗
PubMed1998

RHD genotyping in weak D phenotypes by multiple polymerase chain reactions.

BACKGROUND: Weak D phenotypes involve a quantitative variation of D. The genomic basis in weak D has been disputed, however. STUDY DESIGN AND METHODS: Five sequence-specific polymerase chain reactions (SSP-PCRs) on exons 2, 5, and 7 of the RHD gene were evaluated in 248 white and 98 Japanese blood donors and compared with the results obtained by amplification of intron 4 and serology. All methods and SSP-PCR testing on the 3' non-coding region of the RHD gene were applied to the genotyping of 94 DNA samples derived from individuals expressing weak D phenotypes. RESULTS: Concordant results were obtained with all genotyping and phenotyping methods in testing 201 D-positive and 145 D-negative donors. Four of 94 weak D samples were typed as D-negative by amplification of intron 4 and SSP-PCR on exon 5. Phenotyping with monoclonal antibodies revealed a DVI category in one of these cases and DFR phenotype in three of these cases. One weak D sample, which reacted like normal D-positive cells with all applied monoclonal antibodies, was typed falsely negative by SSP-PCR on exon 5 because of a point mutation at nucleotide 667 (T-->G) that resulted in a Phe223Val amino acid substitution. In this individual, heterozygosity was found at two other amino acid positions (Glu233Gln and Val238Met) by restriction fragment length polymorphism analysis. CONCLUSION: Genetic diversity in weak D phenotypes is rare. Only 1 of 90 true weak D phenotypes (1.1%) had a genetic variation in testing on seven gene regions of the RHD gene.

Asian People↗