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S Panzer

Publications and source records attributed to S Panzer.

At least 91 records · Page 5Linked to original sources
PubMed1996

Genotyping of the human platelet antigen systems 1 through 5 by multiplex polymerase chain reaction and ligation-based typing.

BACKGROUND: Platelet-specific antibodies may be involved in refractoriness to platelet transfusions, disorders such as neonatal alloimmune thrombocytopenia, and post-transfusion purpura. Genotyping for the major human platelet antigen (HPA) systems HPA-1 through HPA-5 is of considerable help in establishing the diagnoses of these diseases. STUDY DESIGN AND METHODS: A new genotyping method is described. Alleles of all five systems are amplified in a multiplex polymerase chain reaction. Subsequently, aliquots of the amplification products are thermocycled in the presence of a pair of allele-specific oligonucleotide probes and a heat-stable ligase. After heat denaturation, the probes hybridize adjacent to complementary sequences of the amplification product. In a perfect match, the two probes become covalently joined. Detection of the ligation product is performed with an enzyme-linked immunosorbent assay. RESULTS: Complete concordance of genotypes between the ligation-based typing and established genotyping methods was determined in 54 Austrian (HPA-1, -2, -3, and -5) and 56 Japanese (HPA-4) individuals. Ligation-based genotyping of HPA-1 polymorphism using platelet-derived RNA as starting material gave concordant results in all 15 cases tested. CONCLUSION: Multiplex polymerase chain reaction in combination with ligation-based typing allows fast typing of large numbers of platelet donors and screening for critical antigens in pregnant women.

Base Sequence↗
PubMed1996

Salivary duct determination in Drosophila: roles of the EGF receptor signalling pathway and the transcription factors fork head and trachealess.

Organogenesis in Drosophila embryos begins at 4-5 hours of development as the expression of organ-specific genes is initiated. The salivary primordium, which occupies the ventral epidermis of parasegment 2, is among the earliest to be defined. It is soon divided into two distinct regions: the more dorsal pregland cells and the more ventral preduct cells. We show that it is the opposing activities of the Drosophila EGF receptor (DER) signaling pathway and the Fork head transcription factor that distinguish these cell types and set up the boundary between them. DER signaling acts ventrally to block fork head expression in the preduct cells, thereby restricting gland identity to the more dorsal cells. Fork head in turn blocks expression of duct-specific genes in the pregland cells, thereby restricting duct identity to the more ventral cells. A third regulatory activity, the Trachealess transcription factor, is also required to establish the identity of the preduct cells, but we show that it acts independently or downstream from the DER:fork head confrontation. In trachealess mutants, subdivision of the salivary primordium occurs normally and the dorsal cells form glands, but the ventral cells are undetermined. We present a model proposing that trachealess is the crucial duct-specific gene that Fork head represses to distinguish pregland from preduct cells.

Animals↗
PubMed1996

Lupus anticoagulant and thromboembolism: evaluation of fibrinogen, natural inhibitors and molecular markers of thrombosis.

It has been speculated that an impairment in anticoagulant pathways (protein C (PC), protein S (PS), resistance to activated protein C (APC)), may contribute to the thrombotic tendency in lupus anticoagulant (LA) patients. Increased plasma levels of fibrinogen are predictive for arterial thrombosis and increased molecular markers of thrombosis are indicative for activation of the clotting cascade. We investigated 25 patients (20 women) with LA. All patients were stratified according to their thromboembolic history and women according to their history of fetal loss. Eighteen patients had a history of venous or arterial thrombosis, or both. Seven of 16 women with at least one pregnancy had a history of fetal loss. The interrelation among the levels of fibrinogen, PC and PS, and resistance to APC, thrombin-antithrombin III complexes (TAT), prothrombin fragment F1 + 2, D-dimer and the history of thrombotic events and obstetric complications in patients with LA were evaluated. LA patients with a history of venous or arterial thrombosis had a significantly higher fibrinogen level than LA patients without (mean 366 versus 304 mg/dl; P = 0.018). Among 16 women a slightly lower mean TAT level in women with fetal loss was found (2.4 versus 4.3 ng/ml; P = 0.02). No other statistically significant difference in the remaining parameters was yielded in both analyzed subgroups. The results of the study suggest an association between increased fibrinogen levels and the history of venous or arterial thrombosis, or both, in patients with LA. In the other investigated parameters, no relationship to the thrombotic or obstetric history was found.

Adult↗
PubMed1995

Heterogeneity of the T-cell receptor delta gene indicating subclone formation in acute precursor B-cell leukemias.

Precursor B-cell acute lymphoblastic leukemias (B-ALLs) have been shown to be oligoclonal at the Ig heavy-chain (IgH) gene level in up to 40% of cases by Southern blot hybridization. In contrast, oligoclonality as deduced from diversity of T-cell receptor (TcR)-delta gene rearrangements of the immature types (ie, V delta 2-D delta 3, D delta 2-D delta 3) has not been reported, so far. We detected oligoclonality characterized by the coexistence of different junctional regions of identical V delta 2-D delta 3 rearrangements in four childhood precursor B-ALLs. No variation was found in the IgH gene status. Therefore, we define these populations as subclones. Two leukemias displayed the variants in an unequal proportion. In the other two leukemias, for which similar quantities of the coexisting rearrangements were detected, single cell-nuclei polymerase chain reaction (PCR) showed two separate leukemic populations. Subclone formation could not be demonstrated by Southern blot hybridization, but was detectable after PCR amplification of the V delta 2-D delta 3 rearrangement and separation by polyacrylamide gel electrophoresis. The variants arose independently from each other, as deduced from their individual sequences. Using subclone-specific oligonucleotides for hybridization to amplified DNA obtained at diagnosis and during follow-up from bone marrow samples, we demonstrate, (1) specificity of all subclone-deduced probes, (2) that one residual leukemic cell can be detected in 10(4) to 10(5) normal mononuclear cells in a semiquantitative assay, and (3) that none of the subclones persisted after induction therapy. We propose that in a leukemic cell population, TcR-delta gene diversity arises after rearrangements of the IgH genes resulting in apparent clonality at the IgH gene level. However, cells are oligoclonal, if the TcR-delta gene rearrangements are considered. As various subclones may respond differently to chemotherapy, they may hamper the detection of minimal residual disease. Therefore, we use all subclone-specific oligonucleotides for hybridization to amplified DNA from follow-up samples.

Base Sequence↗
PubMed1995

Unstable triplet repeat sequences: a source of cancer mutations?

Numerous mutations have been related to various types of cancer. Short tandem repeats (STRs) are repetitive DNA elements that are often polymorphic in normal populations. Triplet repeat expansion has been related pathogenetically to six diseases: fragile X syndrome, fragile X E syndrome, spinobulbar muscular atrophy, myotonic dystrophy, Huntington's disease, and spinocerebellar ataxia type 1. The characteristics of the GC-rich repeat expansion are diverse and result in profound changes in phenotype, sometimes within a single generation in affected families. We expect that simple repeat expansion will cause some cancers based on our knowledge of these unstable DNA sequences in the previously mentioned genes. This may occur by alteration of tumor suppressor gene expression, alteration in coding features of proteins, or change in bystander oncogene expression such as that which occurs with DNA methylation. The demonstrated meiotic instability could link this mechanism of mutation of familial cancer syndromes. The recent discovery of STR instability at multiple sites in hereditary nonpolyposis colon cancer suggests sequence instability may be a factor in cancer progression. Continued identification of candidate genes containing triplet repeats should allow a ready testing of the hypothesis that unstable simple repeat sequences can cause cancer.

Base Sequence↗
PubMed1995

Maternal alloimmunization against fetal platelet antigens: a prospective study.

Neonatal alloimmune thrombocytopenia (NAIT) is induced by maternal alloantibodies to fetal platelet antigens. This prospective study was carried out to evaluate the incidence of anti-platelet antibodies in 933 mother-child pairs where the mother and child were typed for the human platelet antigens (HPA)-1, -2, -3, -5. Sera from mismatched mother-child pairs were screened for anti-platelet antibodies, anti-HLA class I and blood group ABO IgG antibodies. Platelet-specific antibodies were anti-HPA-3a in one and anti-HPA-5b in 17 neonates, respectively. All these neonates had normal platelet counts. One woman had autoreactive antibodies. Anti-HLA class I and anti-blood group A IgG antibodies were detected in five and four neonates, respectively, born with a platelet count < 150 x 10(9)/l. None of the 11 homozygous HPA-1b mothers became immunized against their heterozygous offspring. The maternal HLA-allotypes HLA-DR52 and -DR6, typically found in individuals immunized against HPA-1a and -5b, respectively, were found in three of 11 HPA-b/b nonresponders and eight of the anti-HPA-5b responders. The results indicate that a risk for NAIT due to HPA-2 and -3 alloimmunization is low. The HLA allotypes do not predict the risk for NAIT due to HPA-1 or -5 alloimmunization. Maternal anti-HPA-5b antibodies do not correlate with the platelet count in the neonate.

ABO Blood-Group System↗
PubMed1994

Autoimmune-thrombocytopenia and SLE in a patient with 5q-anomaly and deletion of the c-fms oncogene.

Autoimmune-thrombocytopenia was the striking feature in a patient with typical clinical symptoms of systemic lupus erythematosus (SLE), complement C4 deficiency, and positive lupus serology. However, myelodysplasia was found in the bone marrow and chromosome analysis revealed a deletion of the long arm of chromosome 5 (5q-anomaly), which was confirmed by a hemizygosity for the c-fms oncogene (CSF-1-receptor) on Southern blot. Autoimmune phenomena reported in conjunction with myelodysplastic syndromes (MDS), e.g., an elevation of antinuclear antibodies, are usually regarded as nonspecific. This case report suggests that SLE can occur in patients with MDS and that a concomitant autoimmune-thrombocytopenia may mask the typical signs of the 5q- syndrome.

Adult↗
PubMed1994

HLA class-I and -II antigens in chronic idiopathic autoimmune thrombocytopenia.

We studied MHC class-I and -II phenotypes in adult Caucasian patients with chronic idiopathic autoimmune thrombocytopenia (cAITP). Forty-five patients (median age 51 years, range 21-78 years) with a median disease duration of 7 years (range 2-26 years) were phenotyped for HLA-A, -B, -C by the standard lymphocytotoxicity test, HLA-DR and -DQ by restriction fragment-length polymorphism (RFLP), and -DP by oligonucleotide typing. Antiplatelet antibodies directed against glycoproteins Ib/IX and IIb/IIIa were determined by monoclonal antibody-specific immobilization of platelet antigens (MAIPA). The comparison of antigen frequencies of the whole group of patients with healthy controls revealed no significant difference for any of the MHC class-I or class-II specificities (p > 0.05). Patients were then divided into groups based on (a) their response to therapy, and (b) on whether they did or did not have detectable anti-platelet antibodies (n = 16 versus n = 29). All patients with a poor response to splenectomy carried the HLA-DPB1*0402 phenotype. The HLA-DPB1*1501 allele was found only among patients with detectable antiplatelet antibodies. These differences were not significant after correction for the number of tested antigens, however. Our data suggest that there is no association between MHC class-I/II alleles and adult cAITP or subgroups thereof.

Adult↗
PubMed1994

Neonatal allo-immune thrombocytopenia due to fetomaternal HPA-1 incompatibility of a homozygous HPA-1a mother and a homozygous HPA-1b father. A case report.

We report a case of neonatal allo-immune thrombocytopenia due to fetomaternal human platelet antigen (HPA)-1 incompatibility. Anit-HPA-1b antibodies were detectable in maternal serum. Repeated treatment of the infant with high-dose IgG effectively raised platelet counts transiently, but the patient remained thrombocytopenic for more than 6 weeks. Serological and DNA analysis revealed that the mother was homozygous HPA-1a and the father homozygous HPA-1b.

Antigens, Human Platelet↗
PubMed1994

A rare leucine 40/arginine40 polymorphism on platelet glycoprotein IIIa is linked to the human platelet antigen 1b.

A rare polymorphism on glycoprotein (GP) IIIa is reported. Sequencing of a 482-base-pair (bp) PCR product of the genomic DNA of GPIIIa revealed a single-base exchange of a G<==>T polymorphism at base 12,569 that created an additional restriction site for MspI. This single-point mutation (frequency in Caucasians 0.00386) is on the HPA-1b gene (HPA-1bvar) and codominantly inherited. The exchange of a G for a T results in a leucine-to-arginine substitution at amino acid 40 from the NH2 terminus. The binding of anti-HPA-1a and -1b antibodies to HPA-1bvar platelets is not influenced.

Arginine↗
PubMed1993

Characterization of CD7+CD19+ lymphoid cells after Epstein-Barr virus transformation.

The early stages of lymphoid differentiation preceding T and B lineage commitment remain poorly defined. We hypothesized that early lymphoid precursor cells are possibly common progenitors and would express a very early T cell-associated Ag (CD7) and a very early B cell-associated Ag (CD19) simultaneously. We therefore transformed CD7+CD19+ fetal bone marrow lymphoid cells using EBV. Extensive characterization of the resulting cell lines indicated that two cell lines corresponded to pre-B and early B cells co-expressing CD7. The third cell line resembled a thymocyte, which co-expressed a number of B cell-associated Ag including CD19 and the stem cell Ag CD34. The two predominantly B lineage cell lines have their Ig genes rearranged, whereas the predominantly T lineage cell line has TCR and Ig H chain genes rearranged. Cross-lineage Ag were not expressed any more after culturing for a prolonged period of time, i.e., B lineage cells became CD7 negative and the thymocyte lineage became negative for the B cell-associated Ag. However, in all three cell lines TCR and/or Ig gene rearrangements remained unchanged. These observations support the existence of a common lymphoid precursor co-expressing CD7 and CD19 that gives rise to either T or B cells.

Antigens, CD↗
PubMed1993

Genotyping provides a reliable tool for the determination of the platelet antigen system HPA-1 in Glanzmann's thrombasthenia.

Glanzmann's thrombasthenia (GT) is an inherited disorder of platelet function, characterized by quantitative or qualitative defects of the platelet glycoprotein (GP) IIb/IIIa complex. Patients with GT may require repeated transfusions and therefore alloimmunization against platelet antigens could become of particular interest. As GPIIIa contains the most important platelet alloantigen system, HPA-1, its diminished expression in GT patients may impede serological determination of the HPA-1 allotype. By immunofluorescence consistent results were obtained in only two out of seven patients. The monoclonal antibody-specific immobilization of platelet antigen test allowed typing of six patients. DNA analysis was feasible in all cases. All seven patients were identified to be homozygous HPA-1a. Thus, provided a normal HPA-1 DNA region, its analysis can serve as a reliable tool for HPA-1 typing in GT even if serological methods fail.

Antigens, Human Platelet↗
PubMed1993

Interaction of IL-1 beta, IL-6 and tumour necrosis factor-alpha (TNF-alpha) in human T cells activated by murine antigens.

We used a mixed leucocyte culture between human T cells and irradiated murine splenocytes which allowed us to distinguish between cytokine production from the responder and stimulator cells by the use of species-specific assays for mRNA up-regulation. Using this model of T cell activation by antigen, we studied the effects of human antigen-presenting cell-derived cytokines IL-1 beta, IL-6 and TNF-alpha on the activation of human T cell subsets. We show in this system that exogenously added IL-1 beta, IL-6 and TNF-alpha induces IL-2 receptor (R) up-regulation and IL-2 production, and proliferation by both CD4+ and CD8+ cells. The addition of IL-1 beta induces IL-6 mRNA, and anti-IL-1 antibodies or an IL-1R antagonist protein completely suppresses IL-6 and TNF-alpha supported proliferation. Similarly, addition of IL-6 or TNF-alpha induces up-regulation of IL-1 beta mRNA. However, anti-IL-6 and anti-IL-6R antibodies only partially block proliferation supported by IL-1 beta. These findings suggest that IL-6 and TNF-alpha will induce IL-2R up-regulation/IL-2 secretion via the induction of IL-1 beta production.

Animals↗
PubMed1993

An acquired cryoglobulinemia which inhibits fibrin polymerization in a patient with IgG kappa myeloma.

A 58-year-old man with multiple myeloma and paraproteinemia (IgG kappa) acquired cryoglobulinemia 2 years after the initial diagnosis of the disease. This cryoglobulin interfered specifically with fibrin aggregation. The patient's fibrinogen was functionally normal; however, clotting times (thrombin clotting time, reptilase clotting time) were prolonged in the untreated plasma and in the supernatant after removal of the cryoglobulins. Untreated patient's serum, and even more pronounced, the cryoprecipitate inhibited the association of fibrin monomers obtained from healthy controls. The inhibitory activity on fibrin aggregation diminished upon treatment-induced reduction of plasma protein levels.

Blood Coagulation Disorders↗