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Biomedical subjects

R Repp

Publications and source records attributed to R Repp.

At least 19 recordsLinked to original sources
PubMed2006

Successful autologous stem cell transplantation in a severely immunocompromised patient with relapsed AIDS-related B-cell lymphoma.

There is now evidence that the tolerability and response to systemic chemotherapy in HIV-infected patients with AIDS-related lymphoma (ARL) is significantly improved by highly active antiretroviral therapy. Here we report an severely immunocompromised AIDS patient with recurrent ARL who was successfully treated with autologous stem cell transplantation (ASCT). We also review the current literature of ASCT in HIV-infected patients.

Adult↗
PubMed2005

An acquired G-CSF receptor mutation results in increased proliferation of CMML cells from a patient with severe congenital neutropenia.

Severe congenital neutropenia (CN) is characterized by a maturation arrest of myelopoiesis at the promyelocyte stage. Treatment with pharmacological doses of recombinant human granulocyte colony-stimulating factor (rh-G-CSF) stimulates neutrophil production and decreases the risk of major infectious complications. However, approximately 15% of CN patients develop myeloid malignancies that have been associated with somatic mutations in the G-CSF receptor (G-CSFR) and RAS genes as well as with acquired monosomy 7. We report a CN patient with chronic myelomonocytic leukemia (CMML) who never received rh-G-CSF. Molecular analysis demonstrated a somatic G-CSFR mutation (C2390T), which led to expression of a truncated G-CSFR protein in the CMML. Normal G-CSFR expression was unexpectedly absent in primary and cultured CMML. In addition, CMML cells showed monosomy 7 and an oncogenic NRAS mutation. In vitro culture revealed a G-CSF-dependent proliferation of CMML cells, which subsequently differentiated along the monocytic/macrophage lineage. Our results provide direct evidence for the in vivo expression of a truncated G-CSFR in leukemic cells, which emerged in the absence of rh-G-CSF treatment and transduces proliferative signals.

Adolescent↗
PubMed2004

Asymmetric multiplex-polymerase chain reaction - a high throughput method for detection and sequencing genomic fusion sites in t(4;11).

Chromosomal translocations are a characteristic feature of leukaemia and other malignant diseases. As clonal markers, they can be applied to identify and quantify the number of malignant cells by polymerase chain reaction (PCR) methods. The translocation t(4;11) is present in >60% of infant leukaemia. In order to facilitate the sequencing of chromosomal breakpoints, we developed an optimized set of 30 PCR primers and a new approach, designated as asymmetric multiplex PCR (am-PCR). Due to the high number of primers, small breakpoint-spanning DNA fragments are obtained in one nested multiplex PCR reaction. All PCR products contain an identical binding site for the initiation of direct sequencing. By using am-PCR, the translocation t(4;11) was examined in bone marrow and blood samples from children with acute leukaemia. Compared with previously described methods for the determination of genomic breakpoints, am-PCR may be advantageous with regard to its simplicity and rapidity. Breakpoint-spanning sequences were also evaluated with regard to their applicability as unique clonal markers to design primers and probes for minimal residual disease quantification by real-time PCR. This approach can easily be adapted to other chromosomal translocations in malignant diseases for the detection and analysis of clone-specific DNA markers.

Chromosome Breakage↗
PubMed2004

Efficient gene delivery with serum into human cancer cells using targeted anionic liposomes.

Success of human gene therapy depends upon the development of delivery vehicles or vectors, which can selectively deliver therapeutic genes to target cells with efficiency and safety. Previous studies have shown an efficient, systemic trans-gene expression in many cell lines (in vitro) by using an anionic liposomal vector, based on the composition of retroviral envelopes (artificial viral envelopes, AVEs). The AVE-liposomes and their complexes with plasmid (DNA) were characterized according to zeta potential measurements and transmission electron microscopy (TEM). We successfully demonstrated that AVE liposomes, dispersed in 10% serum-containing growth medium, efficiently delivered plasmid DNA to HuH-7 (human hepatoma cell line) cells. We assessed the utility of liver-targeted vesicles as a drug/gene delivery system for the treatment of liver diseases. We found that small unilamellar AVE vesicles containing 15 mol% digalactosyl diglyceride (DGDG) are efficiently targeted to the liver via the hepatic asialoglycoprotein receptor.

Carbohydrates↗
PubMed2004

Rituximab consolidation after high-dose chemotherapy and autologous blood stem cell transplantation in follicular and mantle cell lymphoma: a prospective, multicenter phase II study.

BACKGROUND: Patients with follicular (FL) or mantle cell lymphoma (MCL) are incurable with conventional therapy. We investigated the safety and efficacy of rituximab consolidation after autologous stem cell transplantation (ASCT) in order to prevent relapse by clearance of minimal residual disease (MRD). METHODS: Rituximab was given approximately 8 weeks after CD34+ cell enriched ASCT at 375 mg/m2, weekly for 4 weeks. Monitoring of MRD was performed by repetitive PCR analyses. RESULTS: Thirty-one patients were included; one died early after ASCT before rituximab administration. Thirty patients (20 FL, 10 MCL) were evaluable after rituximab consolidation, and 27 of these were assessable for MRD detection. Rituximab consolidation post-ASCT was safe, the most common toxicity being infection. At a median follow-up of 42 months (range 13-96) after ASCT, 25 patients were censored with an actuarial event-free survival (EFS) of 81% at 4 and 5 years. Four patients (two FL, two MCL) relapsed, and one additional MCL patient died unexpectedly in complete remission. PCR-negativity was observed in 22% of the patients before ASCT, 53% post-ASCT (P=0.0547), 72% after rituximab (P=0.0018) and 100% at 6 months post-transplant (P < 0.001). CONCLUSIONS: One single course of rituximab consolidation given after ASCT is safe, may help to eliminate MRD and may translate into improved EFS in both FL and MCL patients.

Adult↗
PubMed2003

Phase I clinical trial of the bispecific antibody MDX-H210 (anti-FcgammaRI x anti-HER-2/neu) in combination with Filgrastim (G-CSF) for treatment of advanced breast cancer.

A phase I study of the bispecific antibody MDX-H210 in combination with granulocyte colony-stimulating factor (G-CSF) was performed in stage IV breast carcinoma patients, overexpressing HER-2/neu. MDX-H210, constructed by crosslinking antigen binding fragments (F(ab') fragments) of monoclonal antibody (mAb) H22 to Fc gamma receptor I (FcgammaRI), and mAb 520C9 to HER-2/neu, respectively, mediates the lysis of tumour cells in vitro, and in human FcgammaRI transgenic mouse models. The proto-oncogene HER-2/neu is overexpressed in approximately 30% of breast cancer patients, and represents a promising target for antibody-based immunotherapy. Fc gamma receptor I (CD64) is an effective trigger molecule, which is expressed on monocytes/macrophages, immature dendritic cells, and G-CSF-primed polymorphonuclear cells (PMN). Patients received G-CSF (Filgrastim) for 8 consecutive days, and cohorts of three patients were treated on day 4 with escalating, single doses of MDX-H210. A total of 30 patients were included, and treatment was generally well tolerated, without reaching dose-limiting toxicity. Side effects consisted mainly of fever and short periods of chills, which were timely related to elevated plasma levels of interleukin 6 and tumour necrosis factor alpha. In the last two cohorts, MDX-H210 plasma levels exceeded 1 microg ml(-1), and on circulating myeloid cells >50% saturation of FcgammaRI was found until day 4. These effector cells were highly effective in antibody-dependent cell-mediated cytotoxicity. Immunohistochemical analyses of tumour biopsies in individual patients documented infiltration of monocytes and PMN after MDX-H210 infusion. Although the clinical course of the disease was not altered by the single dose of MDX-H210, a favourable toxicity profile--even at high doses--and remarkable biological effects were seen when combined with G-CSF. Therefore, the combination of G-CSF and MDX-H210 should be evaluated in further immunotherapeutical strategies.

Adjuvants, Immunologic↗
PubMed2003

Pretherapeutic identification of high-risk acute myeloid leukemia (AML) patients from immunophenotypic, cytogenetic, and clinical parameters.

BACKGROUND: The goal of this study concerned the pretherapeutic identification of high-risk acute myeloid leukemia (AML) patients by data pattern analysis from flow cytometric immunophenotype, cytogenetic, and clinical data. METHODS: Sixty-seven parameters of AML patients at diagnosis were classified for predictive information by algorithmic data sieving using iteratively self optimizing triple matrix data pattern analysis (http://www.biochem.mpg.de/valet/classif1.html). RESULTS: Pretherapeutic predictive values for nonsurvival within five years and two years were 100.0% and 83.2%, respectively, compared to 13.9% and 47.4% for the prediction of survival at five years and two years, respectively. At diagnosis, five-year nonsurvivors showed increased patient age and higher concentration of cells in the analyzed specimen, as well as increased levels of % CD2, CD4, CD13, CD36, and CD45 positive AML blasts. Two-year nonsurvivors were characterized by a data pattern of increased patient age and levels of % CD4, CD7, CD11b, CD24, CD45, TH126, and HLA-DR positive AML blasts and decreased levels of % CD1, CD65, CD95, and TC25 positive AML blasts. Cytogenetic abnormalities were not selected for the optimized discriminatory data patterns. CONCLUSIONS: The comparatively accurate pretherapeutic identification of high-risk AML patients may prove useful for the development of individualized therapy protocols in stratified clinical patients groups.

Acute Disease↗
PubMed2003

Immunophenotyping is an independent factor for risk stratification in AML.

BACKGROUND: Chromosomal abnormalities are one of the most important prognostic factors in acute myeloid leukemia (AML). However, only a limited number of patients have such informative chromosomal abnormalities. The prognostic value of immunophenotyping in this disease is still unclear. METHODS: Seven hundred and eighty-three newly diagnosed AML patients treated in the German SHG-AML trials in 1991 and 1996 were analyzed with a panel of 33 antibodies. Expression was correlated to overall survival, complete remission-rate, and complete remission duration, and tested in a multivariate analysis including other clinical and biological markers. RESULTS: With a median follow-up of 4.3 years, patients with AML blasts negative for CD9, CD11b, CD13, CD34, and CD41, or positive for CD15, CD33, CD38, CD64, and MPO had superior overall survival. This effect was associated with a significantly higher complete remission rate (CD13, CD34, CD41, and CD64) or a longer complete remission duration (CD9, CD11b, and CD64). Cox-regression analysis, including cytogenetic, morphologic, and biologic parameters showed CD9, CD13, CD34, and CD64 as independent factors for overall survival. These markers were used for a prognostic score. Patients were pooled in three groups with highly significant differences of overall survival. The prognostic relevance of this score was confirmed in patients with normal karyotype and/or in younger patients </= 60 years. CONCLUSIONS: Immunophenotyping is not only helpful for diagnosis but is of independent significance for prognosis, and may be useful for risk stratification in AML patients.

Acute Disease↗
PubMed2003

A new missense mutation of the vasopressin-neurophysin II gene in a family with neurohypophyseal diabetes insipidus.

OBJECTIVE: Autosomal dominant familial neurohypophyseal diabetes insipidus is a rare disorder characterized by polydipsia and polyuria. We present the results of the molecular analysis of the AVP-NPII gene of a German kindred. METHODS: All three exons of the gene were amplified by polymerase chain reaction and sequenced. RESULTS: In 7 affected individuals a new missense mutation (1770G > T) in exon 2 was found predicting a cysteine to phenylalanine substitution at codon 58 in the neurophysin II domain (NPII). CONCLUSION: As a result of this mutation a cysteine residue is exchanged, which is involved in a disulfide bond with cysteine 44 of the NPII moiety, hypothesizing that the resulting misfolded protein may lead to chronic neurotoxicity by accumulation of these products in the endoplasmatic reticulum.

Adolescent↗
PubMed2002

[Increased response rate with rituximab in relapsed and refractory follicular and mantle cell lymphomas -- results of a prospective randomized study of the German Low-Grade Lymphoma Study Group].

BACKGROUND AND OBJECTIVE: Rituximab has shown a high activity in relapsed follicular lymphomas when given alone. Further on, phase-II-studies indicate that its addition to chemotherapy may improve the response rate substantially. However, so far, prospective randomized studies have not been available. PATIENTS AND METHODS: In 1998 the GLSG started a multicenter trial in patients with relapsed or refractory indolent lymphoma or mantle cell lymphoma. A fludarabine-containing regimen (FCM) was chosen for salvage therapy, with fludarabine 25 mg/m(2)/d 1-3, cyclophosphamide 200 mg/m(2) d 1-3 and mitoxantrone 8 mg/m(2) d 1. A total of four courses, every 4 weeks were given. Patients were prospectively randomized for FCM alone or the immunochemotherapy with R-FCM (375 mg/m(2) one day before FCM) RESULTS: About 147 randomized patients 93 had follicular, 40 mantle cell and 14 lymphoplasmocytic/-cytoid lymphoma. Statistical analysis was performed by sequential testing and indicated for 94 fully evaluable patients a significant advantage for the R-FCM-arm, with an overall response rate of 83 % as compared to 58%, when treated with FCM alone (CR: 35 % vs. 13 %). Similar improvements of remission rate were detected in the different lymphoma subgroups, especially in MCL (OR: 65 % vs. 33 %). Both treatment options were associated with hematological toxicities of grade III and IV, but well tolerated; infectious complications were rare, with no difference between the two treatment groups. CONCLUSION: This prospectively randomized trial demonstrates for the first time a significant improvement of the combined immunochemotherapy related to the remission rate in patients with relapsed or refractory indolent lymphoma.

Adult↗
PubMed2002

Definition of risk factors for death, end stage renal disease, and thromboembolic events in a monocentric cohort of 338 patients with systemic lupus erythematosus.

BACKGROUND: The survival rate in patients with systemic lupus erythematosus (SLE) has improved dramatically during the past four decades to 96.6% (five year) in the Erlangen cohort, but it is nearly three times as high as in an age and sex matched control population. Reasons for death are mainly cardiovascular diseases (37%) and infections (29%). OBJECTIVE: To find risk factors existing at disease onset for a severe outcome in the Erlangen cohort. PATIENTS AND METHODS: By using a database of 338 patients with SLE from a single centre, documented at least one to 15 years and including Systemic Lupus International Collaborating Clinics/American College of Rheumatology (SLICC/ACR) damage score data and index (SDI) and an activity score (European Consensus Lupus Activity Measurement (ECLAM)), a retrospective search was made for risk factors for a severe outcome like death, end stage renal disease (ESRD), and thromboembolic events (TE) in SLE. For this purpose, multivariable Cox regression models were analysed using the statistical package SPSS 10.0 for Windows. RESULTS: The following were defined as risk factors for death at disease onset: male sex (p<0.001, relative risk (RR)=3.5), age >40 at disease onset (p<0.0001, RR=19.9), nephritis (p<0.05, RR=1.6), a reduction of creatinine clearance (p<0.001, RR=1.8), heart disease (p=0.05, RR=1.5), and central nervous system (CNS) disease (p=0.06, RR=1.6). An increase in the SDI of two or more points from the first to the third year of disease was the worst prognostic factor (p<0.0001, RR=7.7). The existence of Ro or nRNP antibodies, or both, was protective (p<0.05, RR =0.1). A low C3 (p<0.01 RR=3.0) and splenomegaly (p<0.01 RR=2.7) at disease onset turned out to be risk factors for ESRD besides a nephritis. In patients with hypertension (p<0.05) and/or high titres of dsDNA antibodies (>70 U/l) (p<0.01) and/or a mean ECLAM score of 4 (p<0.01) in the course of disease, a prevalence of ESRD was recorded in 9% (p<0.05) and 10% (p<0.01), and 8% (p<0.01) v 4% in the whole group. Analysis of risk factors at disease onset for TE identified positive lupus anticoagulant (p=0.17, RR=1.6), cryoglobulins (p<0.05, RR=1.8), and nephritis (p=0.05, RR=1.4), in addition to an age >40 at disease onset. CONCLUSIONS: A subgroup of patients in the Erlangen cohort with a typical clinical and serological phenotype at disease onset that is at high risk for a worse outcome was identified. Identification of these white patients at risk at disease onset will enable treatment to be intensified and thereby possibly prevent or better control late stage manifestations.

Adult↗
PubMed2002

Fcgamma receptor IIa, IIIa, and IIIb polymorphisms in German patients with systemic lupus erythematosus: association with clinical symptoms.

BACKGROUND: Receptors for IgG play an important part in immune complex clearance. Several studies have identified polymorphisms of receptors for the Fc fragment of IgG (FcgammaR) as genetic factors influencing susceptibility to disease or disease course of systemic lupus erythematosus (SLE). OBJECTIVE: To examine these possibilities by evaluating a panel of clinical parameters in a cohort of 140 German patients with SLE for correlations with the FcgammaRIIa, IIIa, and IIIb polymorphisms in an explorative study. METHODS: 140 German patients with SLE according to American College of Rheumatology (ACR) criteria and 187 German controls were genotyped for the FcgammaRIIa, IIIa, and IIIb polymorphisms. Associations between FcgammaR genotypes, combined genotypes and clinical as well as laboratory features were analysed. RESULTS: No significant skewing of any of the three FcgammaR polymorphisms was seen in the German SLE cohort studied. Various clinical and serological parameters were found more frequently and at younger age in homozygous patients with the genotypes IIA-R/R131 or IIIA-F/F158 than in patients with IIA-H/H131 or IIIA-V/V158. These effects were even more pronounced in patients with the low binding combined phenotypes of the FcgammaRIIa, IIIa (double negative phenotypes) and FcgammaRIIa, IIIa, and IIIb (triple negative phenotypes). In patients with the double negative IIA and IIIA genotypes significantly higher frequencies of nephritis (63% v 33%) and proteinuria according to ACR criteria (58% v 11%), anaemia (84% v 55%), and anticardiolipin antibodies (63% v 22%) were found than in patients with the double positive genotypes. Patients with the IIA-R/R131 genotype and the double negative homozygous genotype had an earlier incidence of clinical symptoms, haematological and immunological abnormalities. Accordingly, SLE is diagnosed earlier in these patients, the difference reaching statistical significance only in the double negative v the double positive genotype (26.3 v 39.5 years) and the IIIA-F/F158 genotype v the rest (26.7 v 32.0 years). Most relevant is the fact that a higher median disease activity (ECLAM score) was demonstrated, both in the IIA-R/R131 homozygous (3.3 v 2.7) and the double negative (3.4 v 2.3) patients, reaching statistical significance in the first group. CONCLUSION: The results of this explorative study support the view that the FcgammaRIIa/IIIa and IIIb polymorphisms constitute factors influencing clinical manifestations and the disease course of SLE but do not represent genetic risk factors for the occurrence of SLE. Higher frequencies of clinical symptoms, haematological and immunological abnormalities as well as an earlier onset of clinical symptoms, haematological and immunological markers of active disease were found in patients with the IIA-R/R131 genotype and the double negative and triple negative genotypes.

Adolescent↗
PubMed2001

Mechanisms of G-CSF- or GM-CSF-stimulated tumor cell killing by Fc receptor-directed bispecific antibodies.

Studies with gene-modified mice have recently reinforced the importance of Fc receptor-mediated effector mechanisms for the therapeutic efficacy of rituxan and herceptin - two clinically approved antibodies for the treatment of tumor patients. We investigated Fc receptor-dependent tumor cell killing by mononuclear and granulocytic effector cells - comparing human IgG1 antibodies against CD20 or HER-2/neu with their respective FcgammaRI (CD64)-, FcgammaRIII (CD16)-, or FcalphaRI (CD89)-directed bispecific derivatives. With blood from healthy donors as effector source, human IgG1 and FcgammaRIII (CD16)-directed bispecific antibodies proved most effective in recruiting mononuclear effector cells, whereas tumor cell killing by granulocytes was most potently triggered by FcalphaRI-directed bispecific constructs. Granulocyte-mediated tumor cell lysis was significantly enhanced when blood from G-CSF- or GM-CSF-treated patients was investigated. Interestingly, however, both myeloid growth factors improved effector cell recruitment by different mechanisms, which were furthermore dependent on the tumor target antigen, and on the selected cytotoxic Fc receptor.

Animals↗
PubMed2001

Increased endothelin-1 and decreased adrenomedullin gene expression in the stenotic tissue of congenital pelvi-ureteric junction obstruction in children.

OBJECTIVES: To test the hypothesis that the gene expression of endothelin-1 and adrenomedullin may be altered in stenotic tissues of patients with congenital hydronephrosis caused by pelvi-ureteric junction (PUJ) obstruction. MATERIALS AND METHODS: Using real-time reverse transcription-polymerase chain reaction, mRNA of smooth muscle-constricting endothelin-1 and of smooth muscle-relaxing adrenomedullin was quantified in tissue specimens of 20 patients with PUJ obstruction (mean age 5.1 years, SD 7.0) and of 21 controls with normal PUJs (mean age 23.5 years, SD 24.2). RESULTS: The amount of endothelin-1 mRNA in stenotic specimens was higher than in the controls, indicated by significantly lower threshold cycles (Ct values) in real-time PCR for the target gene in the obstructive tissue, with mean (SD) values of 24.9 (1.6) and 26.0 (2.1) (P < 0.05), respectively. The endothelin-1/CD31 ratio was significantly higher in the patients (P < 0.05) than in controls. In addition, adrenomedullin gene expression in the obstructed junctions was significantly lower than in normal junctions, with higher Ct values for the patient group of 26.7 (1.6) vs 25.2 (1.8) (P < 0.05) and lower adrenomedullin mRNA when standardized to glyceraldehyde-3-phosphate dehydrogenase (GAPDH) (P < 0.05), CD31 (P < 0.01) and smooth muscle alpha-actin mRNA (P < 0.01). The two groups showed no significant differences for GAPDH and CD31 mRNA content, whereas there was about twice as much alpha-actin mRNA in stenotic tissues than in unaffected PUJs, shown by the lower Ct values for the patient group of 16.9 (2.0) vs 17.9 (2.6) (P < 0.05). Furthermore, endothelin-1, adrenomedullin and alpha-actin mRNA amounts were independent of age. CONCLUSION: Taken together these results provide evidence that the production of autocrine/paracrine acting endothelin-1 and adrenomedullin is altered in tissues of patients with genuine PUJ obstruction, and may be involved in the pathogenesis of congenital hydronephrosis.

Adolescent↗
PubMed2001

Course of placental 11beta-hydroxysteroid dehydrogenase type 2 and 15-hydroxyprostaglandin dehydrogenase mRNA expression during human gestation.

BACKGROUND: During human pregnancy, 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) plays an important role in protecting the fetus from high maternal glucocorticoid concentrations by converting cortisol to inactive cortisone. Furthermore, 11beta-HSD2 is indirectly involved in the regulation of the prostaglandin inactivating enzyme 15-hydroxyprostaglandin dehydrogenase (PGDH), because cortisol reduces the gene expression and enzyme activity of PGDH in human placental cells. OBJECTIVE: To examine developmental changes in placental 11beta-HSD2 and PGDH gene expression during the 2nd and 3rd trimesters of human pregnancies. METHODS: In placental tissue taken from 20 healthy women with normal pregnancy and 20 placentas of 17 mothers giving birth to premature babies, 11beta-HSD2 and PGDH mRNA expression was determined using quantitative real-time PCR. RESULTS: Placental mRNA expression of 11beta-HSD2 and PGDH increased significantly with gestational age (r=0.55, P=0.0002 and r=0.42, P=0.007). In addition, there was a significant correlation between the two enzymes (r=0.58, P<0.0001). CONCLUSIONS: In the course of pregnancy there is an increase in 11beta-HSD2 and PGDH mRNA expression in human placental tissue. This adaptation of 11beta-HSD2 prevents increasing maternal cortisol concentrations from transplacental passage and is exerted at the gene level. 11beta-HSD2 up-regulation may also lead to an increase in PGDH mRNA concentrations that, until term, possibly delays myometrial contractions induced by prostaglandins.

11-beta-Hydroxysteroid Dehydrogenase Type 2↗
PubMed2001

Diagnostic and scientific applications of TaqMan real-time PCR in neuroblastomas.

This review summarizes the present data on the diagnostic and scientific applications of TaqMan real-time PCR in neuroblastomas, a novel fluorescence-based method for quantitation of gene expression and gene copy number variations as gene amplification and locus haploinsufficiencies. Particular emphasis is spent on precision and accuracy and the comparison of TaqMan real-time PCR with more traditional methods for quantitative PCR. Provided a proper assessment for each new marker, this method has been shown to be an easy, fast and reliable alternative to the more traditional methods for the determination of MYCN amplification and neuropeptide Y gene expression. The combination with single cell picking in the neuroblastoma tissue may be a future target of the application of real-time PCR.

Biomarkers, Tumor↗