Search PubMed⌕ Search

Biomedical subjects

R Lynen

Publications and source records attributed to R Lynen.

At least 19 recordsLinked to original sources
PubMed2003

HFE genotype and parameters of iron metabolism in German first-time blood donors - evidence for an increased transferrin saturation in C282Y heterozygotes.

BACKGROUND: Hemochromatosis is usually inherited in an autosomal recessive mode and associated with missense mutations in the hemochromatosis gene (HFE), an HLA class 1 related gene. However the degree of penetrance is presently matter of debate. METHODS: To elucidate the frequency of HFE mutations in a German population and the relationship between genotype and phenotype, we determined the HFE C282Y and H63D genotypes in 500 first-time blood donors using an allele-specific ligase chain reaction (LCR). Ferritin and transferrin saturation (TS) of all donors found to have at least one mutation were compared to gender- and age-matched controls. RESULTS: The C282Y allele frequency was 46 in 1000 chromosomes (4.6 %). The allele frequency of H63D was 108 in 1000 (10.8 %) chromosomes. We found three persons homozygous for H63D, nine compound heterozygotes and none homozygous for C282Y. TS was elevated in C282Y heterozygotes (p = 0.002) and C282Y/H63D compound heterozygotes (p = 0.04) compared to wild-type controls. Serum ferritin tended to be elevated in compound heterozygotes (p = 0.053). Mean corpuscular volume (MCV) and hemoglobin (MCH) were not different from controls. CONCLUSION: The frequency of HFE mutations in the tested population was comparable to those of other northern European populations. The elevated TS in subjects carrying a single copy of the C282Y mutation suggests that C282Y heterozygosity is associated with an increased intestinal iron absorption and might therefore offer a selection advantage in conditions of iron depletion.

Alleles↗
PubMed1999

A dispermic chimerism in a 2-year-old Caucasian boy.

Detection of two different cell populations in a child is a rare event. The following case of a dispermic chimera was diagnosed before surgery due to problems in blood group determination. A 2-year-old phenotypically male child was admitted for correction of a penoscrotal hypospadia and unilateral cryptorchism. During presurgical laboratory investigation, difficulties in blood group determination occurred. Blood group typing was performed by the DiaMed-ID Micro Typing System and by FACS. Additionally, cytogenetic analysis of lymphocytes and analysis of DNA polymorphisms in different tissues were performed. Two populations of red blood cells were detected, O cells accounting for 75% and B cells for 25%. Analysis of DNA-PCR polymorphisms in lymphocytes, nails, and in cells of the oral mucous membrane demonstrated a chimerism, with two alleles inherited from the father and one from the mother. A cytogenetic analysis of cultured lymphocytes showed a mosaic 46, XY/46,XX. Surgery revealed a prostatic utricle grade III, also called pseudovagina; genitography confirmed a vagina. Bilateral gonad biopsy showed a testis on one side and an ovary on the other. This case of chimerism represents a true hermaphroditism that most probably developed by double fertilization of one or more egg nuclei by two sperms.

Blood Grouping and Crossmatching↗
PubMed1999

Application of RHD and RHCE genotyping for correct blood group determination in chronically transfused patients.

BACKGROUND: In chronically transfused patients, conventional blood group typing may be impossible because of mixed-field agglutination. STUDY DESIGN AND METHODS: In 27 patients with congenital anemia and lifelong transfusion history, genotyping for D, RHD, and RHCE was performed with polymerase chain reactions. These results were compared with the blood group typing results documented in the medical record. RESULTS: Two of 27 cases had been typed D-negative by serologic tests and D-positive by genotyping. In 20 patients, the CDE formula had been determined serologically according to the medical record; 4 of these patients were Cc by serologic tests and C/C by genotyping. One patient typed ee by serologic tests, and genotyping revealed heterozygosity (E/e). CONCLUSION: In patients with a lifelong transfusion history, serologic blood group determination may be impossible, and pretransfusion test results are not always available or reliable. In whites, Rh-matched transfusions are possible with genotyping. The genetic background of the RH genes has to be elucidated in other ethnic groups, such as in black patients with sickle cell disease, before genotyping can be applied without restriction.

ABO Blood-Group System↗
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↗
PubMed1997

Frequency and causes of refractoriness in multiply transfused patients.

The use of leukocyte-depleted blood components has become the standard therapy for multiply transfused patients during the past few years, as a measure to reduce the frequency of alloimmunization and refractoriness. We assessed frequency and causes of refractoriness, defined as a repeated 24-h post-transfusion platelet count below 20,000/microliters, in 145 consecutive patients who received three or more single-donor platelet concentrates during a 1-year period. Flow-cytometric detection of anti-platelet antibodies and a glycoprotein-specific ELISA were applied for the diagnosis of alloimmunization. Forty patients (27.6%) had at least one episode of refractoriness. In 25 of these 40 patients (62.5%), nonimmune factors (fever, sepsis, coagulopathy, splenomegaly) alone were the cause. In 15 refractory patients alloantibodies were detected. In seven patients (17.5%), alloimmunization alone caused an inadequate transfusion response, while in eight refractory patients (20.0%) alloimmunization and fever or sepsis were present. HLA antibodies were detected in 17 patients (11.7%); three patients (2%) had platelet-specific antibodies in addition to HLA antibodies; in two patients panreactive platelet antibodies were detectable. All 17 patients had a history of previous transfusions or pregnancy. We did not observe primary immunization in patients transfused exclusively with filtered (leukodepleted) blood products. Our data suggest that alloimmunization in patients with a negative risk history can be prevented by the exclusive use of leukodepleted blood components.

Antigens, Human Platelet↗
PubMed1997

[Rh-D genotyping for exon 2, 5 and 7 of German and Japanese blood donors with sequence specific polymerase chain reaction].

RHD genotyping from fetal cells was applied for the detection of the RHD gene in the fetus of immunized Rh-D-negative women. Additionally, RHD genotyping was applied for the characterization of Rh-D variants. Although 44 nucleotide substitutions are known to code for 35 amino acid differences between the RHCE and the RHD gene, only a few polymorphisms have been investigated yet. We investigated 7 RHD-specific nucleotides on exons 2, 5, and 7 with sequence-specific primers and 1 nucleotide with ligation-based typing. All RHD genotyping results were correlated with serological results and established genotyping methods in 116 German and 98 Japanese blood donors, because different genetic sequences coding for Rh-D polypeptides have been described in different ethnic groups. Sequence-specific amplification of D-specific sequences was concordant with the serological result in all blood donors tested. However, ligation-based typing on exon 5 gave false-negative results in 7 donors. In summary, 5 new sequence-specific PCRs have been evaluated for further characterization of Rh-D variants. Furthermore, the methods described allow nested PCR and thus may help in determination of the fetal RhD status from maternal peripheral blood during pregnancy.

Antibodies, Anti-Idiotypic↗
PubMed1996

Flow cytometric detection of platelet-reactive antibodies and application in platelet crossmatching.

BACKGROUND: Alloimmunization against HLA or platelet antigens can cause refractoriness to platelet transfusions in multiply transfused patients. Crossmatching of platelet concentrates is effective in overcoming this problem. STUDY DESIGN AND METHODS: A flow cytometric assay was used for simultaneous detection of lymphocyte-reactive and platelet-reactive antibodies in a single sample using fluorescein isothiocyanate-labeled anti-IgG. This assay was compared with the monoclonal antibody-specific immobilization of platelet antigens (MAIPA) assay in selected sera containing HLA and platelet antibodies. In a further study, this assay was compared with lymphocytotoxicity test results from thrombocytopenic patients, for whom platelet concentrates were ordered. The results of both assays were then correlated with the 1-hour corrected count increment, with a corrected count increment greater then 7500 considered as an adequate transfusion response. RESULTS: The results of the MAIPA and flow cytometric assay in detecting platelet-reactive antibodies correlated well (p<0.0001, r = 0.84). The sensitivity and specificity of the flow cytometric assay in detecting platelet-reactive antibodies were 94.7 and 96.3 percent, when the MAIPA assay was taken as a reference. In unselected sera from patients, the sensitivity and specificity of the flow cytometric assays were, respectively, 72.7 and 91.7 percent in detecting lymphocyte-reactive antibodies and 70.6 and 77.7 percent in detecting platelet-reactive antibodies, when the lymphocytotoxicity test was used as a reference. With regard to an adequate transfusion response, the sensitivities and efficiencies were 20.0 and 82.1 percent, 33.3 and 84.3 percent, and 70.0 and 88.6 percent for the lymphocytotoxicity test and the lymphocyte-reactive and platelet-reactive flow cytometric assays, respectively. CONCLUSION: Flow cytometric crossmatching appears to be an effective method of detecting platelet-reactive antibodies that may affect the success of platelet transfusions. This procedure is well-suited for routine conditions and can be performed within 2 hours.

Antibodies, Monoclonal↗
PubMed1995

Flow cytometric analyses of the subclasses of red cell IgG antibodies.

We report on flow cytometric IgG subclass determinations of red cell antibodies using polyclonal FITC-labeled antibodies. The limit of detection of this method was 1 ng anti-D per 1 x 10(7) red cells. The inter- and intra-assay coefficients of variance were 8.2 and 2.3%, respectively. In 8 newborns with a positive direct antiglobulin test (DAT) in the gel centrifugation test (GCT), due to ABO antibodies, IgG1 was detected in all and IgG2 additionally in 4 of these cases. In 5 severe cases of hemolytic disease of the newborn (HDN) due to anti-D, large amounts of IgG1 were found, and in 3 of these 5, IgG3 in combination with IgG1. In 8 mild or moderate HDN cases (4 anti-D, 2 anti-E, 1 anti-Fya, 1 anti-Jka), phototherapy sufficed, and IgG1 was the only antibody. In 7 adult patients with malignant lymphoma and a positive DAT (GCT), only small amounts of IgG1 red cell autoantibodies could be demonstrated by flow cytometry. In 5 further patients with malignant lymphoma, a positive DAT, and severe hemolytic anemia, large amounts of IgG1 autoantibodies were found and IgG3 was also present in 3 of these cases. Flow-cytometric determination of IgG subclasses may be a useful tool in immunohematology, since subclass determinations were possible in all of these cases. This method is suited for clinical routine and offers the possibility of sufficient standardization.

Adult↗
PubMed1994

[Flow cytometry analysis of IGG subclasses of auto- and alloantibodies in autoimmune hemolytic anemia and hemolytic disease of the newborn].

Red cell IgG antibodies capable of causing hemolytic disease of the newborn (HDN) or autoimmune hemolytic anemia (AIHA) have been analyzed concerning their IgG subclasses using flow cytometry. The results were always in agreement with those of the direct Coombs test. Anti-A and/or anti-B able to cause HDN belonged to the IgG1 subclass (4/8 cases) or to the subclasses IgG1 and IgG2 (4/8 cases). In 3 out of 4 cases of HDN caused by Rh antibodies the antibodies belonged to the subclasses IgG1 and IgG3. In patients with lymphoma but without AIHA, red cell autoantibodies were often found to be IgG1 only (n = 10), in low concentrations. In cases of acute AIHA in adults caused by IgG autoantibodies the subclass IgG3 was found in addition to IgG1 in 4/5 cases. In our opinion flow cytometry should become substantial for immunohematological diagnostics.

Adult↗
PubMed1993

[Initial results of a prospective study with automated solid phase and column/agglutination techniques in screening for transfusion relevant IgG antibodies].

We report the first results of a prospective study concerning antibody screening in transfusion recipients. We compared the standard tube test (Liss Coombs) with two commercial tests for the detection of red cell IgG antibodies: (1) a column/agglutination test and (2) a microplate/solid-phase system. The results of the study demonstrate several significant advantages of the two methods as compared with the standard tube test. The new methods, especially the microplate test, are superior in determining red cell antibodies which are relevant to transfusion. The two methods are more sensitive and, when automated, more efficient and safer as compared with the standard tube test.

Blood Grouping and Crossmatching↗
PubMed1993

[Hemolytic-uremic syndrome in pneumococcal meningitis and infection. Importance of T-transformation].

A 4 month old girl developed a severe hemolytic uremic syndrome (HUS) following pneumococcal sepsis and meningitis. As a result of the hemolytic anemia and thrombocytopenia with associated gastrointestinal bleeding several red blood cell and thrombocyte transfusions became necessary. No plasma was transfused to the patient and all cellular blood components to be transfused were washed thoroughly in order to avoid the administration of eventually dangerous donor anti-T antibodies. Continuous peritoneal dialysis was performed for 23 days until sufficient spontaneous urine production was resumed. From the start of increased hemolysis T-transformation of the patient's red blood cells could be shown; bacterial neuraminidase was proven in the patient's serum, which could be neutralized in vitro by a commercial intravenous IgG preparation. The direct Coombs-Test was negative and no significant amounts of anti-T antibodies were detectable in the patient's serum at any stage of the disease. Our observation suggest that the T-transformation itself has caused the increased hemolysis and not an antigen-antibody (T-anti-T) reaction. In cases of HUS und proven T-transformation, intravenous IgG preparations should be tried therapeutically to inhibit the bacterial neuraminidase.

Antigen-Antibody Reactions↗
PubMed1991

Characterization and quantification of anti-T in human serum using a reliable hemolysis test.

The need of fresh-frozen donor plasma with a low level of anti-T has been emphasized recently. Anti-T, as administered by transfusion of fresh-frozen plasma, has been accused repeatedly of enhancing hemolysis in septic children with T transformation of red cells. Therefore, a new hemolysis test for the quantification of anti-T in human serum has been developed. With our test, anti-T-poor plasma donors can be found. Additional results raise substantial doubt as to the pathogenetic role of anti-T in the development of the hemolytic-uremic syndrome, found in septic children with red-cell T transformation. It is impossible to predict in vivo hemolysis induced by anti-T knowing the temperature characteristics and the ionic conditions causing this antibody to mediate hemolysis in vitro. Obviously, T transformation itself plays the major pathogenetic role in these patients, and not the presence of anti-T. In the case of disseminated intravascular coagulation, a content of anti-T cannot be construed as prohibiting transfusion of fresh-frozen plasma to such patients.

Antibodies↗
PubMed1990

[Hemolytic-uremic syndrome in an adult with T-cryptantigen liberation].

Haemolytic uraemic syndrome was diagnosed in a 36-year-old woman with acute renal failure (creatinine 10.5 mg/dl), haemolytic anaemia (haemoglobin 9.7 g/dl, lactate dehydrogenase 1926 U/l) and thrombopenia (98,000/microliters). After initial plasmaphereses and high doses of furosemide all symptoms disappeared within three weeks. The lectin tests demonstrated that the illness was connected with the liberation of T-crypt-antigen (Thomsen-Friedenreich antigen) on the erythrocytes. This special form of the haemolytic uraemic syndrome (neuraminidase-induced haemolytic uraemic syndrome) has previously been observed almost exclusively in children. However, for diagnosis and differentiation of haemolytic uraemic syndromes the presence of liberated T-antigen on erythrocytes should also be tested for in adults.

Acute Kidney Injury↗
PubMed1990

Patients with anti-Vel--immunohematological characterization and transfusion management.

As reported by other authors we can confirm that the frequency of the blood group Vel negative in Lower Saxony is 1:4000. We report on a patient whose serological characteristics (IgM- and IgA-anti-Vel) made the transfusion of Vel positive blood impossible. Since it was not possible to obtain sufficient Vel negative red cell units in time, the patient was convinced to donate blood for autologous transfusions. This should be the procedure of first choice in the transfusion management of such patients.

Blood Group Antigens↗
PubMed1990

T and Tk transformation in hemolytic uremic syndromes.

In two cases of hemolytic uremic syndrome (HUS) the bacterial pathogenesis of the disease could be elucidated by lectin red cell agglutination tests. The possible role of anti-T and anti-Tk antibodies is discussed. Transfusions of fresh plasma had no adverse effects. The fatal outcome in one case was caused by disseminated intravascular coagulation (DIC).

Agglutination Tests↗
PubMed1989

Stages of anti-N-like immunization: a further contribution to problems arising from anti-N-like antibodies in hemodialysis patients.

In the past years, the discussion around problems arising from anti-N-like antibodies has waned in spite of their continuing existence. Even highly sophisticated rinsing procedures of dialysers after sterilisation with Formalin are not capable of preventing an anti-N-like immunization. Therefore, formalin sterilisation should no longer be employed. Three stages of the formalin-dependent anti-N-like immunization are described. Hematological and immunohematological problems in this patient group are documented.

Anemia↗