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R Ladenstein

Publications and source records attributed to R Ladenstein.

At least 91 records · Page 5Linked to original sources
PubMed1995

Regression and progression in neuroblastoma. Does genetics predict tumour behaviour?

Neuroblastoma (NB) is a heterogeneous disease. The clinical course may range from spontaneous regression and maturation to very aggressive behaviour. Stage 4s is a unique subcategory of NB, generally associated with good prognosis, despite skin and/or liver involvement and the frequent presence of tumour cells in the bone marrow. Another type of NB is the locally invasive tumour without bone and bone marrow involvement which can also have a good prognosis, irrespective of lymph node involvement. Unfortunately, there is only limited biological information on such tumours which have not been treated with cytotoxic therapy despite lymph node involvement, residual tumour mass after surgery and/or bone marrow infiltration. In order to find specific genetic changes common to NBs with a benign clinical course, we studied the genetic abnormalities of these tumours and compared them with highly aggressive tumours. We analysed a series of 54 localised and stage 4s tumours by means of in situ hybridisation performed on fresh cells or on paraffin embedded tissues. In addition, we performed classical cytogenetics, Southern blotting and PCR analysis on fresh tumour tissue. The majority of patients had been treated with surgery alone, and in a number of patients tumour resection was incomplete. Deletions at 1p36 and amplifications of the MYCN oncogene were absent, and diploidy or tetraploidy were not seen in any case, with residual localised tumours possessing a favourable outcome. Unexpectedly, one patient with a tetraploid 4s tumour without any genetic structural changes not receiving any cytotoxic treatment, did well. Interestingly, this genetic spectrum contrasted with that of progressing tumours, in which most had genetic aberrations, the deletion at 1p36 being the most common event. These data, although limited, suggest that an intact 1p36 (recognised by D1Z2), the absence of MYCN amplification and near-triploidy (at least in localised tumours), represent prerequisites for spontaneous regression and/or maturation.

Adolescent↗
PubMed1995

First experience with prognostic factors in unselected neuroblastoma patients. The Austrian Neuroblastoma 87 Study.

Between January 1987 and December 1993, 117 patients were registered in the Austrian A-NB87 study. The male/female ratio was 1.18, with 50 patients below the age of 1 year at diagnosis. Patients were assigned to stage according to the result of primary surgery in localised disease. Age, ferritin and neuron specific enolase were used in addition in stage III disease for risk-adapted treatment. Adrenal or pelvic primary tumour sites were mainly associated (81%) with advanced disease. The median observation time of the study is 3.5 years. The overall survival at 3 years was excellent in low stage disease and IVs patients, i.e. 100% for stage I and IIA (20 patients), 92% in stage IVs (13 patients), 81% in stage IIIA (18 patients) and 69% in stage IIB (8 patients). Stage IV (38 patients) showed a survival rate of 51%, whereas stage IIB (10 patients) had the worst outcome in this study, i.e. 20%, due to treatment-related toxicity. Significant unfavourable prognostic factors were neuron specific enolase (NSE) > 100 ng/ml, ferritin > 300 micrograms/ml and amplified MYCN. This study achieved a better survival rate in stage IV patients and a subgroup of stage III in comparison to our previous study (Pädiatrie und Pädologie 1986, 21, 269) and gives the basis to further reduce treatment intensity in low-risk disease based on biological factors. However, prognosis for high-risk cases was still poor in spite of a very aggressive treatment concept.

Age Factors↗
PubMed1995

Impact of megatherapy in children with high-risk Ewing's tumours in complete remission: a report from the EBMT Solid Tumour Registry.

The European BMT Solid Tumour Registry (EBMT-STR) received reports from 21 European transplant centers on 63 patients (50 Ewing's sarcomas and 13 peripheral neuroectodermal tumours) in first (n = 32) or second CR (n = 31) consolidated with megatherapy and BM and/or PSC rescue between December 1982 and November 1992. There were 31 males and 32 females with a median age of 12 years (range 1-30 years) at megatherapy. The median follow-up time since megatherapy is 4 years (range 1 month to 10 years), Thirty-two patients with metastatic disease at diagnosis (22 had metastases to the bone and/or bone marrow) and consolidated in CR1 reached an actuarial event-free survival (EFS) of 21% at 5 years. Thirty one patients in CR2 achieved an actuarial EFS of 32% at 5 years. Favourable outcome was limited to relapse patients with localised disease at initial diagnosis. Distant relapse had a more favourable prognosis than local failure. Analysis of the different megatherapy strategies could not identify a significantly superior approach, nor is there convincing evidence in favour of double graft procedures. From the above results it appears that consolidation treatment by megatherapy contributes to improved EFS rates in high-risk patients compared with historical experience. Major questions for the future to be addressed prior to randomised studies include agreement on the definition of high-risk patients and the most efficient megatherapy procedure.

Adolescent↗
PubMed1995

[The European experience with megadose therapy and autologous bone marrow transplantation in solid tumors with poor prognosis Ewing sarcoma, germ cell tumors and brain tumors)].

Since 1984 a total of 2085 patients with solid tumors have been registered in the European Bone Marrow Transplantation Registry for Solid Tumors (EBMT-STR). The major aim of this registry is to supply data by retrospective analysis for the innovation of prospective, randomized studies. 104 Ewing's sarcoma patients received megatherapy followed by autologous bone marrow transplantation (MGT/ABMT). The 2-year overall survival was 31% in 14 patients with multifocal disease in first complete remission (CR1) and was 37% for 15 patients in second CR (CR2). (6 patients with local disease in CR1 have been excluded.) These results are better than observed under conventional dose chemotherapy. 67 patients were grafted with measurable disease showing a response rate of 72%. The 2-year overall survival was 25% during primary treatments and 33% and 10% for sensitive and resistant relapses, respectively. 201 patients with germ cell tumors received MGT (combinations of platinum derivates, VP16, cyclophosphamide, ifosfamide) followed by ABMT. The overall survival at 5 years was 10% in refractory patients and 58% for 113 responding patients not in CR1 (i.e. first partial remission, CR2 and sensitive relapses). Based on these results and a French randomized trial a prospective, randomized study is underway comparing MGT versus conventional chemotherapy in chemosensitive patients. 219 adults with malignant brain gliomas underwent a program consisting of surgery, MGT (BCNU in the majority)/ABMT and radiotherapy. The overall survival at 3 years was 12%, the median survival was 11 months after ABMT. Life quality after ABMT was good, but no major improvement in terms of prolonged survival was achieved.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

The molecular chaperonin TF55 from the Thermophilic archaeon Sulfolobus solfataricus. A biochemical and structural characterization.

The purification and characterization of a new type of thermostable chaperonin from the archaebacterium Sulfolobus solfataricus is described. The chaperonin forms a hetero-oligomeric complex of two different, but closely related, subunits, which we have assigned TF55-alpha and TF55-beta. Their N-terminal sequences and amino acid residue compositions are reported. Two-dimensional projections of the chaperonin have been reconstructed from electron microscopy images, showing a 9-fold symmetrical complex, about 17.5 nm in height and 16 nm in diameter, with a central cavity of 4.5 nm. The complex is resistant to denaturing agents at room temperature and only pH values lower than 2 lead to dissociation. The separated subunits do not reassemble spontaneously but require Mg2+ and ATP for complex formation. Both subunits are necessary for formation of the TF55 oligomer. Significant structural changes have been observed after phosphorylation, thus providing evidence for a structural mobility during the chaperonin-assisted folding process of a protein. The phosphorylation reaction is modulated by potassium and magnesium ions. Magnesium seems to have an inhibitory effect, whereas potassium enhances this reaction.

Amino Acid Sequence↗
PubMed1994

The lumazine synthase/riboflavin synthase complex of Bacillus subtilis. X-ray structure analysis of hollow reconstituted beta-subunit capsids.

The lumazine synthase/riboflavin synthase complex of Bacillus subtilis consists of an icosahedral capsid of 60 beta subunits enclosing a triplet of alpha subunits. An X-ray structure of 0.32 nm resolution has been obtained for the icosahedral capsid of the native alpha 3 beta 60 complex [Ladenstein, R., Schneider, M., Huber, R., Bartunik, H. D., Wilson, K., Schott, K. & Bacher, A. (1988) J. Mol. Biol. 203, 1045-1070]. beta subunits were isolated after denaturation of the alpha 3 beta 60 complex and were subsequently reconstituted in a ligand-driven reaction yielding artifactual, hollow beta 60 capsids with icosahedral symmetry. Hexagonal crystals (space group P6(3)22) of the reconstituted capsids diffracted X-rays to a resolution of 0.32 nm. Crystallographic intensity data were obtained using synchrotron radiation. Freeze-etched electron-microscopic images and rotation function calculations showed that the hexagonal crystal forms of the artifactual beta 60 capsids and the native alpha 3 beta 60 complex are isomorphous. Orientation and translation parameters of the beta-subunit model were refined by XPLOR rigid-body refinement. The electron-density map was improved by cyclic icosahedral averaging and phase extension from 0.5-0.32 nm resolution. The beta-subunit structure was partially refined by energy minimization and crystallographic refinement (XPLOR) assuming strict icosahedral symmetry (final R factor 30.9% for data at 0.8-0.32 nm resolution). The topology and chain folding of the beta subunits in the artifactual beta 60 capsid are similar to the native alpha 3 beta 60 enzyme. Structural features of the substrate-binding site and the binding of the substrate-analogous ligand 5-nitro-6-ribitylamino-2,4(1H,3H)-pyrimidinedione are discussed. Ligand binding occurs at the pentamer interfaces and includes van der Waals' interactions and hydrogen bonding. The binding pocket shows a hydrophobic region which accomodates the pyrimidinedione ring and a hydrophilic region to which the ribityl side chain binds. Most amino acid residues involved in the active site are conserved as shown by sequence comparisons with the putative lumazine-synthase genes of Escherichia coli and Photobacterium leiognathi. In the final electron-density map, a residual density feature was tentatively assigned to a bound phosphate ion which mimics the binding of the second substrate, 3,4-dihydroxy-2-butanone 4-phosphate. This putative phosphate-binding site involves a highly conserved amino acid sequence containing three basic residues.

Bacillus subtilis↗
PubMed1994

Electrostatic properties of two porin channels from Escherichia coli.

The electrostatic interactions in the channels of OmpF and PhoE porins from Escherichia coli were analysed on the basis of a macroscopic multi-dielectric model of the protein-membrane complex derived from the respective porin X-ray structures. The membrane was represented as layers of distinct dielectric constants corresponding to the aliphatic core and the polar head groups of the lipids. The pKa values of the titratable groups and the electrostatic field in the region of the channel were calculated by the finite difference technique. In spite of the differences in sequences and charge constellations, the calculated electrostatic properties of the two porins are similar in several aspects: (1) unusual titration behaviour (pKa below 7) was found for some groups of the cluster of basic residues at the constriction of the pore; (2) a number of acidic groups buried between the internal loop and the barrel wall are stabilized in their protonated forms at neutral pH; (3) there is a strong transverse electrostatic field in the channel characterized by a screw-like form. The strength of the field is greatest at the region of the constriction zone. This would facilitate the diffusion of solutes with a large dipole moment such as free amino acids. Differences between the electrostatic fields of OmpF and PhoE are mainly confined to that end of the pore that faces the cell exterior in vivo. In OmpF the electrostatic potential is close to zero in this region of the channel, whereas a positive potential was found in PhoE. It was shown that the experimentally observed difference in ion selectivity of the two porins can largely be attributed to this distinct electrostatic property.

Amino Acid Sequence↗
PubMed1994

Autologous bone marrow transplantation for pediatric Wilms' tumor: the experience of the European Bone Marrow Transplantation Solid Tumor Registry.

This survey includes 25 children with Wilms' tumor undergoing high-dose chemotherapy associated with autologous bone marrow transplantation (ABMT) in the period June 1984-December 1991 and enrolled in the European Bone Marrow Transplantation Registry for Solid Tumors. At diagnosis, 12 children presented stage IV disease, 5 stage III, 3 stage II, and 5 stage I. Before ABMT, 21 children had 1 to 4 relapses (median 1); 13 achieved a second or subsequent complete remission (CR), four stage IV children failed to respond to first line treatment and achieved either CR (3 patients), or partial remission (PR) after second line therapy. At high-dose chemotherapy, 17 children were in CR and 8 had measurable disease. Seven different high-dose regimens were administered, even if 20 children received melphalan mostly associated with vincristine and 8 involved field radiotherapy. Three children died early of pneumonitis; 2 developed an acute transient renal failure, 1 a chronic renal failure. Out of the 8 children with target disease at graft, 2 died of toxicity, 5 achieved CR, 1 obtained PR, and only 1 is presently alive in CCR at 39 months after ABMT. Of the 17 children grafted in CR, 8 are alive event-free at 14-90 months (median 34) from ABMT; 7 relapsed at 3-23 months (median 7 months); 1 died of toxicity and 1 was lost to follow-up in CR at 12 months. A salvage attempt with high-dose chemotherapy in children with resistant or poor prognosis recurrent Wilms' tumor seems to be justified. An international cooperative protocol taking into account the increased risk of lung and renal toxicity is necessary.

Adolescent↗
PubMed1994

Optimization of the electrostatic interactions in proteins of different functional and folding type.

The 3-dimensional optimization of the electrostatic interactions between the charged amino acid residues was studied by Monte Carlo simulations on an extended representative set of 141 protein structures with known atomic coordinates. The proteins were classified by different functional and structural criteria, and the optimization of the electrostatic interactions was analyzed. The optimization parameters were obtained by comparison of the contribution of charge-charge interactions to the free energy of the native protein structures and for a large number of randomly distributed charge constellations obtained by the Monte Carlo technique. On the basis of the results obtained, one can conclude that the charge-charge interactions are better optimized in the enzymes than in the proteins without enzymatic functions. Proteins that belong to the mixed alpha beta folding type are electrostatically better optimized than pure alpha-helical or beta-strand structures. Proteins that are stabilized by disulfide bonds show a lower degree of electrostatic optimization. The electrostatic interactions in a native protein are effectively optimized by rejection of the conformers that lead to repulsive charge-charge interactions. Particularly, the rejection of the repulsive contacts seems to be a major goal in the protein folding process. The dependence of the optimization parameters on the choice of the potential function was tested. The majority of the potential functions gave practically identical results.

Computer Simulation↗
PubMed1994

Solution structure and DNA-binding properties of a thermostable protein from the archaeon Sulfolobus solfataricus.

The archaeon Sulfolobus solfataricus expresses large amounts of a small basic protein, Sso7d, which was previously identified as a DNA-binding protein possibly involved in compaction of DNA. We have determined the solution structure of Sso7d. The protein consists of a triple-stranded anti-parallel beta-sheet onto which an orthogonal double-stranded beta-sheet is packed. This topology is very similar to that found in eukaryotic Src homology-3 (SH3) domains. Sso7d binds strongly (Kd < 10 microM) to double-stranded DNA and protects it from thermal denaturation. In addition, we note that epsilon-mono-methylation of lysine side chains of Sso7d is governed by cell growth temperatures, suggesting that methylation is related to the heat-shock response.

Amino Acid Sequence↗
PubMed1994

Comparison of auto versus allografting as consolidation of primary treatments in advanced neuroblastoma over one year of age at diagnosis: report from the European Group for Bone Marrow Transplantation.

A case control study was performed to investigate the potential advantage of allogeneic bone marrow transplantation in advanced or poorly responding neuroblastoma first remission patients using the European BMT Solid Tumor Registry. Seventeen allogeneic and 34 autologous bone marrow transplantation (BMT) cases were matched based on a number of prognostic factors including age, sex, prior treatment duration, pre-graft response status and bone and BM involvement before BMT. Only single BMT procedures are included. The median age at diagnosis was 47 months (range 18-113 months). The median follow-up time since BMT is 58 months (range 13-133 months). The only significant prognostic factor within the allogeneic BMT (p = 0.012) and autologous BMT groups (p = 0.025) was residual skeletal disease before BMT, detected by mIBG in 86% of the cases. However, the progression-free survival was not significantly different: 35% and 41% at 2 years, respectively. Only half of the allogeneic BMT patients had developed graft-versus-host disease (GVHD): 7 of 9 grade I-II and only 2 of 9 grade IV. The median donor age was very young with 74 months (range 20-240 months) and 10 of 17 were sex matched. Thus absence of GVHD risk factors in young children could be the major obstacle in achieving an anti-tumor effect with allogeneic BMT in neuroblastoma.

Bone Marrow Transplantation↗
PubMed1993

Electrostatic evidence for the activation of the glutathione thiol by Tyr7 in pi-class glutathione transferases.

A number of spectrophotometric studies [Graminski, G.F., Kubo, Y. & Armstrong, R.N. (1989) Biochemistry 28, 3562-3568; Liu, S., Zhang, P., Ji, X., Johnson, W.W., Gilliland, G.L. & Armstrong, R.N. (1992) J. Biol. Chem. 267, 4296-4299] have recently shown that the glutathione (GSH) thiol is deprotonated when it is in complex with glutathione S-transferase. Different models have been proposed for the activation of the glutathione S gamma, all pointing out the key role of active-site residue Tyr7. It remains unclear, however, how Tyr7 is actually involved in this process. In this paper we present an analysis of the electrostatic potential in the region of the active site of a pi-class GSH transferase. This analysis provides evidence that the titration behaviour of the absorption band of the E.GSH complex with a pK between 6 and 7 [Liu, S., Zhang, P., Ji, X., Johnson, W.W., Gilliland, G.L. & Armstrong, R.N. (1992) J. Biol. Chem. 267, 4296-4299] should rather be explained by the protonation/deprotonation equilibrium of Tyr7 than by the protonation/deprotonation equilibrium of the GSH thiol group itself. On the basis of this conclusion, a mechanism for activation of GSH is proposed: the Tyr7 OH group is deprotonated by the influence of the protein charge constellation and the peptide dipoles. Thus it acts as a general base, promotes proton abstraction from the GSH thiol and creates a thiolate anion with high nucleophilic reactivity.

Animals↗
PubMed1993

Synovial sarcoma of childhood and adolescence. Report of the German CWS-81 study.

BACKGROUND: Synovial sarcoma is the third most common pediatric soft tissue tumor. It requires an aggressive approach to achieve a cure. However, optimal treatment modalities adapted to disease extension and histologic variants have not been determined because there is little information about prospectively treated patients. METHODS: A multicenter trial for soft tissue sarcomas (Protocol CWS 81) was conducted in West Germany between 1981-1985, and 31 patients with synovial sarcoma were registered. Treatment included multiagent chemotherapy and irradiation after initial tumor excision or biopsy. The male-female ratio in this group was 1:1.6 with a median age of 14 years (range, 1-19 years). The median follow-up time after diagnosis was 101 months (range, 77-131 months). RESULTS: The overall event-free survival (EFS) for patients with synovial sarcoma was 74.2% at 5 years. Group I-II tumors had a significantly better prognosis than those in Group III-IV (EFS at 5 years 84.4% and 58.3%, respectively; P = 0.024). Small tumors (< 5 cm) responded better than larger tumors (> or = 5 cm; EFS, 93% versus 58%; P = 0.029). Synovial sarcoma involved the extremities in 28 patients who had a better outcome compared with those with extremity rhabdomyosarcoma in this study (EFS for Group I-IV was 82% versus 24%, P = 0.001). CONCLUSIONS: The results appeared superior to previous experience using radical surgery alone and suggested that after initial, nonmutilating surgery, adjuvant chemotherapy, and irradiation contributed to the improved long-term survival.

Adolescent↗
PubMed1993

Translocation (12;13) in a case of infantile fibrosarcoma.

Cytogenetic analysis of an infantile fibrosarcoma showed the presence of a t(12;13) and numerical changes of chromosomes 15 and 20. Until now only non-random gain or loss of total chromosomes as well as one case with a deletion at 17p have been reported for this kind of tumor. This report represents the first cytogenetic description of an aggressive infantile fibrosarcoma with a translocation.

Chromosomes, Human, Pair 12↗
PubMed1993

High-dose chemotherapy with autologous bone marrow rescue in advanced stage IV neuroblastoma.

In order to better evaluate the role of bone marrow purging procedures in the treatment of stage IV neuroblastoma, two similar groups of patients, prospectively treated during the same period at Léon Bérard Center, Lyon, France, and at Giannina Gaslini Institute, Genova, Italy, were reviewed. 18 children were treated in Lyon with a protocol including induction chemotherapy, surgery and a single course of high-dose chemotherapy followed by purged autologous bone marrow rescue. 21 patients were treated in Genoa with a very similar protocol which did not include purging procedures. Progression-free survival at 6 years was 12% (95% confidence interval 0-24%), without any difference between the two series of patients. The only prognostic factor for long-term survival was the persistence (or not) of bone lesions and the presence of metastatic disease (bone or bone marrow) at graft. The small numbers in the two groups and the very poor outcome make it difficult to conclude on the efficacy of purging.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1993

Indication and limits of megatherapy and bone marrow transplantation in high-risk neuroblastoma: a single centre analysis of prognostic factors.

76 patients with high risk neuroblastoma were treated with one (41 patients) or two consecutive courses (35 patients) of megatherapy. Autologous bone marrow transplantation was scheduled after each megatherapy. Univariate analysis confirmed two prognostic factors in this heterogeneous study population: no bone lesions before megatherapy and age at diagnosis of less than 2 years with 5-year progression-free survival rates of 51% (P < 0.0007) and 53% (P < 0.025), respectively. Both factors were shown to be of independent prognostic significance using the Cox proportional hazard model. Identification of prognostic factors should help to define the interest and limits of megatherapy. We consider that elective megatherapy followed by innovative treatments appears justified in patients with persisting bone disease. In contrast, megatherapy has to be re-evaluated for patients showing a more favourable response pattern and/or young age, ideally in a randomised, prospective trial.

Adolescent↗
PubMed1993

Double megatherapy and autologous bone marrow transplantation for advanced neuroblastoma: the LMCE2 study.

In the LMCE1 study using a single course of megatherapy most of the relapses occurred during the first 2 years after autologous bone marrow transplantation. A second pilot study (LMCE2) was therefore set up using a double harvest/double graft approach with two different megatherapy regimens. Objectives were to test the role of increased dose intensity on response status, relapse pattern and overall survival. Thirty-three patients (20 boys, 13 girls) with a median age of 53 months at first megatherapy (range, 17-202 months) entered this study. They were cases either with refractory disease in partial response after second line treatment for stage 4 neuroblastoma (n = 25) or after relapse from stage 4 (n = 5) or stage 3 disease (n = 3). All patients received Etoposid and/or Cisplatinum (or Carboplatin) containing treatments before megatherapy. The first megatherapy regimen was a combination of Tenoposid, Carmustine and Cisplatinum (or Carboplatin), the second applied Vincristin, Melphalan and Total Body Irradiation. The first harvest was scheduled 4 weeks after the last chemotherapy, the second 60 to 90 days after megatherapy. All marrows were purged in vitro by an immunomagnetic technique. Median follow up time since first megatherapy is 56 months. Response rates for evaluable patients were 65% (complete response rate: 16%) for megatherapy 1 and 60% (complete response rate: 25%) for megatherapy 2. Considering that only patients with delayed response or relapse were eligible for this pilot study the overall survival was encouraging with 36% at 2 years and still 32% at 5 years. The costs for these survival rates were high in terms of morbidity (four early and four late toxic deaths; toxic death rate: 24%). Double harvesting may have the disadvantage of delayed engraftments related in part to a disturbance of marrow microenvironment by megatherapy 1. This double megatherapy approach achieved a prolonged relapse free interval (median 11 months, range 2-31 months) in patients reaching megatherapy 2 and justifies further evaluation of concepts with consecutive dose-escalation.

Adolescent↗