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S Santoso

Publications and source records attributed to S Santoso.

At least 37 records · Page 2Linked to original sources
PubMed1999

The alpha2 gene coding sequence T807/A873 of the platelet collagen receptor integrin alpha2beta1 might be a genetic risk factor for the development of stroke in younger patients.

The polymorphisms C807T and G873A of the platelet integrin alpha2beta1 (collagen receptor glycoprotein [GP] Ia-IIa) are linked to the expression density of this receptor. The GPIa T807/A873 allele causes a higher receptor expression, enhancing platelet binding to collagen. This might present a genetic predisposition for the development of thromboembolic complications. In this case-control study, the genotypes of the GPIa C807T polymorphism and presence of conventional risk factors (hypertension, diabetes mellitus, and smoking) were compared in stroke patients and patients without cerebrovascular disease (non-CVD patients) </=50 years of age (n = 45 and 41, respectively) and in stroke patients and non-CVD patients more than 50 years of age (n = 182 and 129, respectively. In patients </=50 years of age, the T807 allele was the only overrepresented variable (P =.023; odds ratio, 3.02; 95% confidence interval, 1.20 to 7.61) and an independent risk factor, whereas the presence of conventional risk factors was similar between stroke patients </=50 years of age and non-CVD patients </=50 years of age. Large epidemiological studies should prove whether the platelet collagen receptor GPIa-IIa T807 allele is an independent risk factor for the development of stroke in younger patients.

Adult↗
PubMed1999

Association of the platelet glycoprotein Ia C807T gene polymorphism with nonfatal myocardial infarction in younger patients.

Recently, we have shown that two alleles of the glycoprotein (GP) Ia gene, designated C807 and T807, are associated with low or high platelet GPIa-IIa density and consequently with slower or faster rate of platelet adhesion to type I collagen, respectively. This polymorphism could therefore present a genetic predisposition for the development of thrombotic disease and hemostasis. We investigated the relationship of the GPIa C807T dimorphism to the risk of coronary artery disease (CAD) and myocardial infarction (MI). An allele-specific polymerase chain reaction (PCR) was developed for genotyping of C807T polymorphism. DNA samples from 2237 male patients who underwent coronary angiography on account of coronary heart disease as verified illness or presumptive diagnosis were genotyped. The odds ratio was calculated as an estimate of the relative risk by multiple logistic regression. We found a strong association between the T allele and nonfatal MI among individuals younger than the mean age of 62 years (n = 1,057; odds ratio, 1.57; P =.004). The odds ratio of MI increased for T807 carriers with decreasing age. The highest odds ratio was detected within the youngest 10% of the study sample (<49 years; n = 223; odds ratio, 2. 61; P =.009). In contrast, no evidence of an association between C807T dimorphism with CAD was found. Our findings suggest that inherited platelet GP variations might have an important impact on acute thrombotic disease.

Age Factors↗
PubMed1999

The use of allele-specific recombinant Fc gamma receptor IIIb antigens for the detection of granulocyte antibodies.

The Fcgamma receptor IIIb (FcgammaRIIIb) for the Fc domain of IgG is expressed exclusively on neutrophils. The FcgammaRIIIb bears allotypic polymorphisms referred to as NA1, NA2, and SH, which are known for their frequent involvement in alloimmune and autoimmune neutropenias as well as in transfusion reactions. The bactericidal capacity of isolated neutrophils is easily activatable, and activation results in self-desintegration, thus preventing storage of neutrophils. As a result, only freshly isolated granulocytes can be used for antibody screening, often making it impossible to use typed panel cells. To provide a readily available source of typed panel cells, we therefore established stable mammalian cells expressing recombinant NA1, NA2, and SH antigens. We isolated mRNA from typed neutrophils and then transcribed it in cDNA. The cDNA that codes for the different forms of the FcgammaRIIIb was amplified by polymerase chain reaction and was subsequently subcloned into the mammalian expression vector pcDNA3. Chinese hamster ovary (CHO) cells were transfected with allele-specific constructs, and stable cell lines expressing FcgammaRIIIb were selected by flow cytometry. Because human sera show high background fluorescence with transfectants in flow cytometry, the monoclonal antibody-specific isolation of granulocyte antigens (MAIGA) assay was performed. By MAIGA assay, we tested 14 well-characterized human alloantibodies directed against the antigens NA1, NA2, and SH; 5 FcgammaRIIIb-specific isoantibodies; and 12 FcgammaRIIIb-reactive autoantibodies. Except one NA1- and one SH-specific alloantibody, all other antibodies could be identified by the use of CHO transfectants. In contrast to neutrophils, fixed CHO cells can be stored at 4 degrees C for at least 4 weeks or stored frozen for a longer period. This longer shelf life of the transfected CHO cells compared with isolated neutrophils will simplify the detection of the clinically most important FcgammaRIIIb-reactive alloantibodies and autoantibodies.

Alleles↗
PubMed1999

Low prevalence of a polymorphism of platelet membrane glycoprotein Ib beta associated with neonatal alloimmune thrombocytopenic purpura in Asian populations.

Iy alloantigen system is the first polymorphism of platelet glycoprotein Ib beta reported to cause neonatal alloimmune thrombocytopenic purpura. We investigated the allelic frequency of Iy alloantigen among Japanese and Korean populations by polymerase chain reaction-restriction fragment length method to determine the possibility of alloimmunization against Iy. Two hundred and nine Japanese and 97 Korean subjects were examined. All 306 individuals were homozygous for glycine at amino acid position 15 and negative for Iy. The allelic frequency of Iy in these populations was calculated to be less than 0.0016. Alloimmunization associated with Iy antigen in Asian populations seems unlikely from these results.

Amino Acid Substitution↗
PubMed1998

Nucleotide polymorphisms in the alpha2 gene define multiple alleles that are associated with differences in platelet alpha2 beta1 density.

Three allelic differences in the alpha2 gene are associated with expression levels of the alpha2beta1 integrin on the platelet surface. We have previously defined two linked silent polymorphisms in the alpha2 gene coding region at nucleotides 807 (C or T) and 873 (G or A). We have now identified one rarer nucleotide polymorphism in the coding region at nucleotide 837 (T or C) and four additional linked polymorphisms within the introns that flank these coding sequences. Moreover, we have determined that the alloantigenic Br polymorphism, which resides in a distal coding region at nucleotide 1648, is also linked to the 837 polymorphism. Thus, three alpha2 gene alleles, defined by eight nucleotide polymorphisms, have now been discovered. Allele 1 (807T/837T/873A/Brb) is associated with increased levels of alpha2beta1; allele 2 (807C/837T/873G/Brb) and allele 3 (807C/837C/873G/Bra) are each associated with lower levels of alpha2beta1. Finally, we also show here that the rate of platelet attachment to type I collagen in whole blood under conditions of high shear rate (1,500/s) is proportional to the density of alpha2beta1 receptors on the platelet surface. Thus, the density of platelet alpha2beta1 could have an important impact on platelet adhesion to collagen in whole blood and therefore on platelet function in vivo, contributing to an increased risk of thrombosis or to bleeding in relevant disease states.

Alleles↗
PubMed1998

Heparin-induced thrombocytopenia: new insights into the impact of the FcgammaRIIa-R-H131 polymorphism.

Heparin-induced thrombocytopenia (HIT), a severe complication of heparin treatment, can be associated with new thrombotic complications. HIT antibodies activate platelets via the platelet Fcgamma-receptor (FcgammaRIIa), which carries a functionally relevant polymorphism (FcgammaRIIa-R-H131). The effect of this polymorphism on the clinical manifestations of HIT is controversial. We determined prospectively the FcgammaRIIa-R-H131 genotypes in 389 HIT patients, in 351 patients with thrombocytopenia or thrombosis due to causes other than HIT and without detectable HIT antibodies, and in 256 healthy blood donors. For this purpose, a novel nested sequence-specific primer-polymerase chain reaction (SSP-PCR) was developed. FcgammaRIIa-R/R131 was found to be overrepresented in the HIT patients (27%) compared with the control groups (non-HIT patients [21%] and blood donors [20%]). In a subgroup of 122 well-characterized HIT patients, the genotype distribution in patients presenting with thrombocytopenia only was compared with that of patients who developed thromboembolic complications. The frequency of FcgammaRIIa-R/R131 among patients with thrombotic events was significantly elevated (37% v 17%; P = .036). Our results indicate that genotype distribution can be correlated to the clinical outcome of patients with HIT. We speculate that the reduced clearance of immune complexes in patients with the FcgammaRIIa-R/R131 allotype causes prolonged activation of endothelial cells and platelets, thus increasing the risk for thrombotic complications.

Antigens, CD↗
PubMed1998

Purification, crystallization, and preliminary X-ray crystallographic data analysis of small heat shock protein homolog from Methanococcus jannaschii, a hyperthermophile.

A gene coding for a small heat shock protein homolog from the hyperthermophilic methanogenic Archaeon Methanococcus jannaschii was cloned. This gene was overexpressed in Escherichia coli harboring rare codon tRNAs and its protein purified and crystallized. Crystals displayed the space group R3 with unit cell dimensions a = b = 171.46 A and c = 102.13 A in a hexagonal axis setting. These crystals grew in one week and diffracted to 3.2 A resolution. The presence of eight molecules in the asymmetric unit gives a Vm value of 2.2 A3/Da and a solvent content of 44% by volume. The 24-molecule complex is generated from a subunit by a combination of crystallographic threefold symmetry and three types of noncrystallographic symmetries (a two-, a three-, and a fourfold).

Archaeal Proteins↗
PubMed1998

Clinical aspects and typing of platelet alloantigens.

Platelet alloantigens can induce the formation of corresponding alloantibodies when exposed to phenotypically negative individuals. These antibodies are responsible for fetal and neonatal alloimmune thrombocytopenia, posttransfusion purpura, passive alloimmune thrombocytopenia and transplantation-associated thrombocytopenia and may contribute to platelet transfusion refractoriness together with HLA antibodies. Besides antibody detection laboratory diagnosis of the clinical syndromes requires alloantigen typing. Furthermore, typed platelet donors are a prerequisite for effective platelet transfusion therapy. Different techniques for phenotyping are well established and easy to perform but they rely on the availability of antisera. Since the molecular genetic background of the clinically most relevant alloantigens has been elucidated during the last years various genotyping methods have been applied to the platelet membrane polymorphisms and thus facilitated widespread platelet alloantigen typing. Generation of antibodies from phage display libraries and of lymphoblastoid cell lines from donors with all genetic variants will allow further developments.

Adult↗
PubMed1997

Characterization of a new alloantigen (SH) on the human neutrophil Fc gamma receptor IIIb.

Polymorphic structures of the neutrophil Fc gamma receptor IIIb (Fc gamma RIIIb) result in alloantibody formation that causes alloimmune neonatal neutropenia and transfusion reactions. Alloantigens located on Fc gamma RIIIb include the antigens NA1 and NA2. In four cases of alloimmune neonatal neutropenia, granulocyte-specific alloantibodies directed against a thus far unknown antigen were detected by granulocyte agglutination and immunofluorescence tests in the maternal sera. By the use of the monoclonal antibody-specific immobilization of granulocyte antigens (MAIGA) assay, the new antigen, termed SH, was located on the Fc gamma RIIIb. Nucleotide sequence analysis of the Fc gamma RIIIb coding region from a SH(+) individual showed a single-base C-->A mutation at position 266, which results in an Ala78Asp amino acid substitution. A family study confirmed that this nucleotide difference is inherited, and corresponds to the SH phenotype. Serologic typing of 309 randomly selected individuals showed an antigen frequency of 5% in the white population. The same frequency was found by genotyping, for which a technique based on polymerase chain reaction (PCR) using sequence-specific primers (PCR-SSP) was developed. Typing of all SH(+) individuals for NA1 and NA2, and PCR-restriction fragment length polymorphism analysis of the NA-specific PCR products from five SH(+) individuals using the SH-specific endonuclease SfaN 1 showed that SH antigen is very probably the result of an additional mutational event in the NA2 form of the Fc gamma RIIIB gene. Immunochemical studies also demonstrated that the SH determinants reside on the 65- to 80-kD NA2 isoform of the Fc gamma RIIIb. Our findings show the existence of an additional polymorphism of the Fc gamma RIIIb, which can result in alloantibody formation causing alloimmune neonatal neutropenia.

Adult↗
PubMed1996

Platelet autoantibodies (IgG, IgM, IgA) against glycoproteins IIb/IIIa and Ib/IX in patients with thrombocytopenia.

Autoimmune thrombocytopenic purpura (AITP) is most frequently induced by platelet-specific autoantibodies against epitopes on platelet GP Ib/IX or GP IIb/IIIa. These antibodies are reliably detected on the patients' autologous platelets. So far, studies on the characterization of platelet autoantibodies have been restricted to IgG antibodies. We used the monoclonal antibody immobilization of platelet antigens assay (MAIPA) in a modified version to detect GP-specific IgG, IgM, and IgA antibodies. Platelets of 46.2% of patients carried elevated amounts of IgG antibodies. IgM and IgA antibodies were observed less frequently and showed only weak OD signals in the MAIPA assay. Circulating IgG antibodies in serum were found in 11.5% of patients. Circulating IgM autoantibodies were observed in 8.9% and IgA antibodies in no patient with AITP. Results of direct MAIPA assay were compared with the reactivity of eluates in the platelet adhesion immunofluorescence assay and were found to be highly concordant. Patients with AITP in remission carried high percentages of anti-GP IIb/IIIa. Findings made in this study suggest that autoantibodies of the IgM and IgA classes play only a minor role in the pathogenesis of AITP.

Autoantibodies↗
PubMed1995

The alpha 6-integrin receptor in pancreatic carcinoma.

BACKGROUND/AIMS: The alpha 6-containing integrin was suggested to be involved in the process of tumor invasion and metastasis. Therefore, the aim of the study was to investigate the expression and function of this adhesion receptor in pancreatic carcinoma. METHODS: Integrin expression was investigated in pancreatic tissue and tumor cell lines using immunohistochemistry. Radioimmunoprecipitation was used to determine the complex composition of alpha 6. To analyze the function of the alpha 6-containing integrin in pancreatic cancer, in vitro adhesion, migration, and invasion experiments were performed. RESULTS: The alpha 6-containing integrin was differentially expressed in normal pancreas and pancreatic carcinoma. Immunoprecipitation of different pancreatic carcinoma cell lines showed that alpha 6 was expressed together with the beta 4 subunit as alpha 6 beta 4 complex. However, adhesion of pancreatic cancer cells to laminin could be inhibited with anti-alpha 6 and anti-beta 1 integrin antibodies but not by anti-beta 4 integrin antibody. Migration of the cells through laminin was almost completely inhibited by anti-beta 1 antibody but not by other anti-integrin antibodies. Tumor cell invasion through a reconstituted basement membrane was only slightly inhibited by anti-alpha 6 antibody. In contrast, a marked inhibition was observed using anti-beta 1 antibodies, anti-alpha 2-anti-alpha 5 antibodies, and RGDS. CONCLUSIONS: The alpha 6-containing integrin is a laminin adhesion receptor in pancreatic carcinoma cells, possibly involved in tumor invasion through the basement membrane.

Antigens, Surface↗
PubMed1995

NA gene frequencies in the German population, determined by polymerase chain reaction with sequence-specific primers.

BACKGROUND: The granulocyte antigens NA1 and NA2 are often targets of granulocyte antibodies causing immune neutropenia. Currently, NA typing relies on the properties of the typing sera or antibodies and the techniques used. Therefore, the technique of polymerase chain reaction with sequence-specific primers (PCR-SSP) was adapted for DNA-based NA typing and was used for determining the NA gene frequencies in the German population. STUDY DESIGN AND METHODS: The genomic DNA of 160 unrelated healthy individuals was typed for NA1 and NA2 by PCR-SSP. In 60 granulocyte samples, the NA phenotype was additionally determined by the antigen capture assay and the granulocyte immunofluorescence test (GIFT) and correlated with the genotyping results. RESULTS: Results of the antigen capture assay and PCR-SSP correlated precisely, whereas nine individuals were typed heterozygous only by GIFT. The gene frequencies were 0.35 for NA1 and 0.65 for NA2. CONCLUSION: The NA2 gene is more frequent in the German population than the NA1 gene, as determined by genotyping using PCR-SSP. In contrast to GIFT, which showed an error rate for NA typing of 15 percent, PCR-SSP and the antigen-capture assay are more reliable methods of NA typing of granulocytes.

Base Sequence↗
PubMed1995

Genomic RFLP typing of human platelet alloantigens Zw(PlA), Ko, Bak and Br (HPA-1, 2, 3, 5).

The diallelic human platelet alloantigen systems 1-5 have been found to result from single base pair substitutions in the encoding genes of platelet membrane glycoproteins IIIa, Ib, IIb and Ia. This is the basis of DNA methods for determination of platelet alloantigens. In this study, 98 blood donors were typed in the HPA-1, 2, 3 systems and, for the first time, in the HPA-5 system. Serologically obtained data (MAIPA and platelet agglutination) were compared with results from analysis of restriction fragment length polymorphisms (RFLP). Discordances were found in the HPA-2 and 3 systems and can be ascribed to false typing results in both the serological and genomic methods. In the HPA-1, 2 and 5 systems, all samples were typed correctly with RFLP analysis. Serologically, two donors were falsely typed positive with anti-HPA-2b in platelet agglutination and one donor with anti-HPA-3a in MAIPA assay. In the HPA-3 system, another four donors were misinterpreted to be HPA-3a negative in RFLP analysis. Possible technical problems in PCR-RFLP-typing are discussed and another strategy of HPA-1 typing using the restriction enzyme Scr FI is evaluated.

Antigens, Human Platelet↗
PubMed1995

Genotyping of the granulocyte-specific NA antigens from small quantities of blood or serum.

To avoid the well-known shortcomings of phenotyping granulocytes for the NA antigens using NA-specific human sera, a DNA-based method to determine the NA genotype was developed. Genomic DNA was isolated from blood cells or serum, amplified by polymerase chain reaction (PCR), immobilized on nylon membrane and genotyped using digoxigenin-labeled, sequence-specific oligonucleotides (SSO). The genotyping results of whole blood samples from 54 and of serum from 20 individuals correlated perfectly with our phenotyping using the antigen capture assay MAIGA. In three cases with the phenotype "NA-null" no hybridization of the NA-specific oligonucleotides occurred. These data show that SSO is a reliable method for NA genotyping especially if only small volumes of blood or even only serum probes are available.

Base Sequence↗
PubMed1995

Alloimmunization against Iy, a low-frequency antigen on platelet glycoprotein Ib/IX as a cause of severe neonatal alloimmune thrombocytopenic purpura.

Neonatal alloimmune thrombocytopenia (NAIT) is usually induced by platelet-specific antibodies against HPA-1a (Zwa) or HPA-5b (Bra). Recently, low-frequency alloantigens on the platelet glycoprotein (GP) IIb/IIIa complex have been discovered as a cause for NAIT. In this report, a new low-frequency platelet-specific alloantigen, Iy, is described which induced severe NAIT. The corresponding antigen was detected in 1/249 unrelated German blood donors. Antibody binding assays with trypsin-digested platelets (ELISA, immunoprecipitation with biotin-labelled platelets) indicate that the antigen is not localized on the glycocalicin moiety of GP Ib alpha, but may be situated on the remnant moiety of GP Ib alpha, GP IX or GPIb beta. Apparently, Iy is not related to the HPA-2 (Ko) antigen system.

Adult↗
PubMed1994

A point mutation leads to an unpaired cysteine residue and a molecular weight polymorphism of a functional platelet beta 3 integrin subunit. The Sra alloantigen system of GPIIIa.

Recently, we described a low frequency platelet alloantigen on human platelet membrane glycoprotein (GP) IIIa, termed Sra, that was involved in neonatal alloimmune thrombocytopenia. To identify the molecular nature of the Sra alloantigen, we analyzed the nucleotide sequence of polymerase chain reaction-amplified GPIIIa mRNA, and found a C2004-->T substitution in seven Sra positive individuals which results in an Arg636-->Cys polymorphism within the cysteine-rich region of GPIIIa. Analysis of allele-specific recombinant forms of GPIIIa that differed only at amino acid residue 636 showed that anti-Sra alloantibodies reacted with the Cys636, but not the Arg636, recombinant form of GPIIIa. Interestingly, under reducing conditions, the Cys636 form of GPIIIa migrated with a slightly increased apparent molecular weight compared with the Arg636 form. Following treatment with Endoglycosidase H, both allelic forms of GPIIIa exhibited the same mobility, however the Sra epitope was lost. Sra positive platelets express the same number of GPIIb-IIIa complexes on their surface as wild-type Sra negative platelets, and also aggregate normally in response to a variety of platelet agonists. Based upon these results, we conclude that 1) GPIIIa residue 636 specifically controls the formation and expression of the Sra alloantigenic determinant, and 2) an unpaired cysteine residue alters the N-linked glycosylation pattern of the extracellular domain of GPIIIa, but affects neither the degree of surface expression nor the adhesive function of the GPIIb-IIIa complex.

Amino Acid Sequence↗
PubMed1994

New polymorphism on platelet glycoprotein IIIa gene recognized by endonuclease Msp I: implications for PlA typing by allele-specific restriction analysis.

BACKGROUND: Five human platelet alloantigen systems have been shown to result from single base pair substitutions in encoding regions of platelet glycoprotein genes IIIa, Ib, IIb, and Ia. For each of the diallelic systems, at least one restriction enzyme is known to cut only one of the two haplotypes. In the PlA system, restriction endonucleases Nci I and Msp I both recognize the PlA2 allele. STUDY DESIGN AND METHODS: A causal observation of an unexpected Msp I restriction pattern of a PlA2/PlA2 individual was made. Samples from 261 blood donors were then typed for antigens of the PlA system by restriction fragment length polymorphism analysis using the Nci I and Msp I restriction enzymes. RESULTS: Applying both enzymes, concordant restriction patterns were found in 258 of 261 blood donors. Three donors had a base pair mutation on the PlA2 allele, which creates an additional restriction site for Msp I 20 base pairs downstream from the PlA polymorphic site. Nucleotide sequence analysis revealed a CT217-->CG217G base exchange resulting in a Leu40-->Arg40 polymorphism of glycoprotein IIIa. CONCLUSION: Presuming that the mutation is not a singular phenomenon and also occurs with the PlA1 haplotype, it could lead to false interpretations of restriction analysis with Msp I. To exclude that possibility, Nci I is preferred for restriction fragment length polymorphism typing in the PlA system.

Antigens, Human Platelet↗