PubMed Health⌕ Search

Biomedical subjects

R Ladenstein

Publications and source records attributed to R Ladenstein.

At least 127 records · Page 7Linked to original sources
PubMed1988

Glutathione transferase from bovine placenta. Preparation, biochemical characterization, crystallization, and preliminary crystallographic analysis of a neutral class PI enzyme.

A method was developed to purify glutathione transferase from bovine placenta by affinity chromatography and fast protein liquid chromatography. The purified enzyme was homogeneous as judged by sodium dodecyl sulfate gel electrophoresis and isoelectric focusing. The dimeric enzyme is composed of identical subunits with a molecular weight of 23,000; its isoelectric point is 6.9. In contrast to previously described isoenzymes of glutathione transferase, the protein we have purified exists in two forms, an active reduced form and a less active oxidized form. These can be reversibly transformed into each other but behave differently in sedimentation analysis, gel chromatography, and gel electrophoresis. These differences may reflect a change in the molecular shape of glutathione transferase. Chemical modification with iodoacetate, iodoacetamide (presumably of thiol groups), phenylglyoxal, and butadione (presumably of arginyl groups), and their inhibitory effects on the activity were investigated. From substrate specificity studies and N-terminal sequence analysis it is obvious that this glutathione transferase must belong to the isoenzyme class pi. The purified enzyme could be crystallized from 1.4 M ammonium sulfate solution, pH 8.0, in the presence of S-hexyl-glutathione. The crystals are tetragonal, with space group P4(1)2(1)2 or P4(3)2(1)2. The cell constants are a = b = 6.1 nm, c = 23.7 nm, alpha = beta = gamma = 90 degrees. The crystals diffract to 0.26-nm resolution and are suitable for x-ray structure analysis.

Amino Acid Sequence↗
PubMed1987

Poorly differentiated, neuron-specific enolase positive round cell tumor with two translocations t(11;22) and t(21;22).

The authors describe a highly malignant, disseminated round cell tumor originating in the ninth rib of a 14-year-old boy. Extensive studies by means of light and electron microscopic examination, histocytochemistry and immunocytochemistry and cytogenetic analysis revealed an undifferentiated, neuron-specific enolase positive round cell tumor with a unique karyotype: 45,XY,-21,t(11;22)(q23;q11), der(22)t(21;22)(q11.2;p11). Thus, despite the absence of definite morphologic features, such as Homer-Wright rosettes, neurosecretory granules and cytoplasmatic processes, these findings suggest a neuroectodermal origin of this bone tumor.

Adolescent↗
PubMed1987

Some observations of a correlation between the symmetry of large heavy-atom complexes and their binding sites on proteins.

Two large, electron dense heavy-metal complexes were found to bind to crystals of heavy riboflavin synthase. The crystallographic analysis by difference Fourier methods shows that the tungsten cluster compound [(W3O2(O2CCH3)6]2+, which has trigonal symmetry, binds to a site on the 3-fold axis of the protein. The heteropolytungstate compound [NaP5W30O110]14-, which has pentagonal symmetry, binds to a site on the 5-fold axis of the protein.

Binding Sites↗
PubMed1987

Heavy riboflavin synthase of Bacillus subtilis. Primary structure of the beta subunit.

Heavy riboflavin synthase is a 1,000,000-Da protein catalyzing the last two reactions of riboflavin biosynthesis. The enzyme complex consists of 60 beta subunits (Mr = 16,200) and approximately three alpha subunits (Mr = 23,000). beta subunits were isolated and cleaved with cyanogen bromide. Fragments were isolated and further digested with trypsin and staphylococcal protease. Peptides were isolated by high performance liquid chromatography. Sequences were determined by automated liquid-phase Edman degradation. The complete sequence of the beta subunit (154 amino acids) was established by direct sequencing of the NH2 terminus, sequencing of overlapping peptides, and carboxypeptidase degradation of the COOH terminus. The sequence shows no detectable homologies to other proteins. A computer prediction of secondary structure elements indicates 34% alpha helix and 30% beta sheet.

Amino Acid Sequence↗
PubMed1986

Heavy riboflavin synthase from Bacillus subtilis. Particle dimensions, crystal packing and molecular symmetry.

Heavy riboflavin synthase from Bacillus subtilis is an enzyme complex consisting of approximately three alpha-subunits (Mr 23.5 X 10(3)) and 60 beta-subunits (Mr 16 X 10(3)). The enzyme has been crystallized from phosphate buffer in a hexagonal crystal modification that belongs to space group P6(3)22. The asymmetric unit of the crystal cell contains ten beta-subunits. The structure of this unusual 10(6) Mr protein has been studied by small-angle X-ray scattering, electron microscopy of three-dimensional crystals, and crystallographic methods. The scattering curves can be interpreted in terms of a hollow sphere model with a ratio of inner and outer radius of 0.3:1. A diameter of 168 A was estimated from the scattering curves, in close agreement with electron microscopic studies. An aggregate with the stoichiometry beta 60, which was obtained by ligand-driven reaggregation of isolated beta-subunits, showed similar shape and dimensions, but a larger value for the ratio Ri/Ra. Electron micrographs of freeze-etched enzyme crystals showed approximately spherical molecules, which were arranged in hexagonal layers. The lattice constants found from the micrographs are in good agreement with the values derived from X-ray diffraction data. Rotation function calculations in Patterson space showed a set of peaks for 2-fold, 3-fold and 5-fold local rotation axes, accurately consistent with icosahedral symmetry and with the particle orientation A shown in the Appendix. The crystal packing can be described as follows: enzyme particles with icosahedral symmetry (point group 532) are located at points 32 of the hexagonal cell, corresponding to positions (0, 0, 0) and (0, 0, 1/2) on the 6-fold screw axes. From the data reported, it may be concluded that the enzyme structure can be described as an icosahedral capsid of 60 beta-subunits with the triangulation number T = 1. The alpha-subunits are located in the central core space of the capsid, but their spatial orientation is incompletely understood.

Bacillus subtilis↗
PubMed1986

Hemophagocytic syndrome with restricted organ involvement: excessive hemosiderosis and fibrosis of the spleen.

We report the case history of a 6 1/2-month-old girl with a hemophagocytic syndrome, pancytopenia, and excessive hepatosplenomegaly. Some extraordinary histological features present in this case--restricted organ involvement, excessive hemosiderosis, and fibrosis of the spleen--further contributed to the well-known problem of distinguishing between infection-associated hemophagocytic syndrome and familial hemophagocytic lymphohistiocytosis.

Diagnosis, Differential↗
PubMed1983

Crystallization and preliminary X-ray diffraction study of heavy riboflavin synthase from Bacillus subtilis.

Crystals of heavy riboflavin synthase from Bacillus subtilis have been obtained from 1.3 M sodium/potassium phosphate, pH 8.7, containing 0.35 mM 5-nitroso-6-(1'-D-ribitylamino)-2,4(1H,3H)-pyrimidinedione. X-ray photographs indicate a hexagonal unit cell with dimensions of a = b = 156.4 A; c = 298.5 A; alpha = beta = 90 degrees; gamma = 120 degrees. The space group was established as P6(3)22 with 12 general positions.

Bacillus subtilis↗
PubMed1975

Substrate-induced redox change of selenium in glutathione peroxidase studied by x-ray photoelectron spectroscopy.

Glutathione peroxidase showed an X-ray photoelectron spectroscopy signal of the Se 3d (3/2, 5/2) electrons at 54.4 eV. After the addition of the acceptor substrate H2O2, a marked shift of this signal to a value of 58.0 eV was observed. Upon subsequent treatment with the donor substrate glutathione, this chemical shift was reversed and the original signal was obtained. These data demonstrate that the enzyme-bound selenium moiety participates in the catalytic process. From the chemical shift obtained it is concluded that the enzyme shuttles between a selenol or selenol derivative in its reduced form and a seleninyl or selenonyl compound in its oxidized form.

Deuterium↗
PubMedDate not supplied

[Nuclear medicine prediction of histologic tumor response of osteosarcoma].

The prediction of histologic tumor response to preoperative chemotherapy was assessed by quantitative scintigraphic follow-up examinations of 54 osteosarcomas. Tumor/non-tumor scintimetry using 99mTc labeled diphosphonates allowed accurate prediction of tumor response in 28 of 30 tumors (accuracy = 93%) after completion and in 10 of 12 osteosarcomas (accuracy = 83%) at the half-way stage of preoperative chemotherapy evaluating only those tumors which showed convergent changes of tumor/non-tumor ratios in the perfusion and the mineral phase. At the half-way stage, however, evaluation of chemotherapy effects was complicated in 12 of 23 osteosarcomas by diverging T/NT ratios. In contrast, quantification and mapping of the tumor plasma volume and 99mTc MDP plasma clearance predicted the histologic tumor response to chemotherapy in 12 of 13 tumors (accuracy = 92%) after completion and in all 11 cases (accuracy = 100%) at the half-way stage.

Antineoplastic Combined Chemotherapy Protocols↗
PubMedDate not supplied

[High-dosage chemotherapy in primary metastasized and relapsed Ewing's sarcoma. (EI)CESS].

BACKGROUND: Patients (pts) with primary metastatic Ewing tumours (ET) have a poor prognosis for event free survival (EFS) compared to pts with localised disease. Following relapse the prognosis is extremely poor. Therefore these primary metastatic and relapsed pts were piloted for high dose therapy (HDT) for the last years. PATIENTS AND METHODS: Between April 1984 and May 1997, 131 ET pts who underwent HDT were registered in the German CESS/EICESS office: 79 pts with primary metastases and 52 pts with relapsed tumours. After induction therapy, consisting of chemotherapy and local therapy, pts received high dose regimens, mainly based on melphalan and/or etoposide (92%). Stem cell rescue was applied from allogeneic bone marrow (n = 13), autologous bone marrow (n = 17), or peripheral blood stem cells (n = 95). The date of analysis was September 1st, 1998. Outcome was calculated by Kaplan-Meier-analyses. RESULTS: The median time under study since high dose therapy was 3.7 years. 35/131 pts (26.7%) were in continuous complete remission, 80/131 pts (61.1%) had relapsed or progressed, 11/131 pts (8.4%) died of complications and 5/131 pts (3.8%) presented with secondary malignancies. For the total group of primary metastatic pts, EFS five years after diagnosis was 19% for pts with HDT and 27% for those without (p = 0.9209). The subgroup of pts with primary lung and bone metastases seemed to benefit from HDT (EFS five years after diagnosis: 34% versus 5%, p = 0.0001). Outcome of pts with an early ET relapse (< 2 years) was also improved by HDT (EFS four years after relapse: 17% versus 2%, p = 0.0001). CONCLUSIONS: The total group of primary metastatic ET pts showed no obvious benefit from HDT, based on melphalan and/or etoposide. Pts with metastases to multiple organ systems, and early relapse seemed to benefit from HDT. The value of HDT should be assessed in prospective clinical trials.

Adolescent↗
PubMedDate not supplied

A single centre experience with allogeneic stem cell transplantation for severe aplastic anaemia in childhood.

BACKGROUND: Severe aplastic anaemia (SAA) is a rare disorder which has a fatal course when allogeneic stem cell transplantation (SCT) or an immunosuppressive regimen is not applied. Stem cell replacement is the only curative approach for these patients but it is limited by the availability of a compatible donor. PATIENTS: Between 1982 and 1993, 18 children (15 boys, 3 girls) with SAA and HLA identical, MLC negative donors underwent SCT in our institution. SAA was preceded by viral infection in 8 patients (3x hepatitis, 1x measles, 1x herpes simplex infection and 3x viral upper respiratory tract infections). It was drug-associated in one and idiopathic in the 9 others. The median age at diagnosis was 9.7 years (range, 2 months to 16 years). Pretreatments included corticosteroids in 11/18 patients, androgens in 4 patients in addition, two had received cyclosporin A (CSA). One patient progressing from Diamond- Blackfan anaemia to SAA had multiple immunosuppressive treatment courses over 7 years before his grand-uncle was identified as donor while 4 patients had no treatment prior to SCT. METHODS: Early SCT (within 90 days after diagnosis) was performed in 9/18 patients and the median interval between diagnosis and SCT was 2.6 months (range, 0.5 to 7 years). The stem cell source was the bone marrow (BM) of a syngeneic twin in 2 patients, the BM (13 patients) or the cord blood (1 patient) of a sibling whilst it was BM from a HLA-phenotypical family donor (1 father, 1 grand-uncle) in two patients. Cyclophosphamide 50 mg/kg on 4 consecutive days was given as preparative regimen to 16 patients but not to the two syngeneic twins. Rejection prophylaxis included total lymphoid irradiation in 5/16 patients while in the other 11 patients donor buffy coat cells were given on days +1 to +4. The syngeneic twins had no need for either approach. Patients received a median number of 3.7 x 10(8)/kg nucleated cells (range, 2.6 to 6.7). Prophylaxis of graft versus host disease (GVHD) was carried out with MTX alone (n = 12), with CSA alone (n = 2) or with both (n = 4). All patients received standard supportive care. RESULTS: The overall survival is 89% at the median observation time of 100 months. The median time to reach 500 granulocytes was 24 days (range, 15 to 40). Median time to become transfusion independent after BMT was 30 days for platelets (range, 2 to 111) and was 28 days for packed red blood cells (range, 6 to 128). Acute GVHD was observed in 10/18 patients and involved only skin in 6 patients, skin and liver or gut in two patients and all 3 organs in another two patients. Seven of 10 patients had grade 1 to 2 a GVHD toxicity, whereas 3 patients experienced grade 3 to 4 acute GVHD. Chronic GVHD developed in 5 patients. Acute transplant related mortality was 5.5%. Cause of death was persisting non engraftment till day +180 after 2 transplant procedures in a boy with previous platelet transfusions from his mother. Late mortality occurred in 2 patients: one chronic GVHD associated haemorrhage 20 months after SCT and one chronic GVHD associated septicaemia 10 years after SCT. CONCLUSION: Although this report reflects patients data accumulated over 15 years, results compare favourably with more recent survival data. Acute and late transplant related toxicity was low in patients undergoing early transplantation with adequate prior supportive care. This data confirms that SCT still should be the first treatment choice if an HLA identical sibling is available.

Anemia, Aplastic↗
PubMedDate not supplied

[Value of prognostic factors in the Austrian A-NB87 Neuroblastoma Study].

AIMS: A multivariate analysis was performed to evaluate the impact of various prospectively evaluated risk factors. PATIENTS AND METHODS: From January 1987 to December 1993, 120 patients were registered in the study. 108/120 patients were eligible. There were 49 girls and 59 boys with a median age at diagnosis of 14 months (range, 0 to 224 months). Patients were classified according to the Evans classification system. LDH, NSE, Ferritin, N-myc amplification, 1p-deletion and ploidy were evaluated at diagnosis. Treatment intensity was based on the results of primary surgery: surgery only for 22 (20%) stage I and IIA patients (macroscopic residue without lymph node involvement), the 9 IIB patients (8,5%) (macroscopic residue with lymph node involvement) had mild chemotherapy in addition (6 x VCR/CYC) and elective radiation (Rx). Stage III patients were divided into 2 groups: IIIA patients (n = 17/16%) had to have ferritin levels under 300 micrograms/ml, NSE lower than 100 ng/ml and age below 2 years at diagnosis and received 6 alternating cycles of DAMO/ MVDOC. If one of these three criteria was not fulfilled, patients were assigned to the more intensive treatment arm stage IIIB (n = 12/11%), i.e. 9 alternating cycles of DAMO/MVDOC/IPE. Stage IV pts (n = 35/32.5%) received 8 MVDOC/IPE cycles and 20 patients received megatherapy followed by stem cell reinfusion in addition. 13 stage IVs patients (12%) were registered and had elective VCR/CYC and/or liver radiation in case of poor clinical condition. The median observation time is 4.2 years (range, 1 to 7.5). RESULTS: The survival rate at 3 years was excellent for localized disease and stage IVs with survival rates of 100% for stage I/IIA and 92% for stage IVs. Stage IIIA patients had an EFS rate of 81% whereas stage IIB patients achieved only 69%. Stage IV patients reached 51%, however outcome was especially poor for stage IIIB patients (20%) due to treatment related toxicities. The toxic death rate in the study was 13% (2 surgical deaths, 8 infections, 4 multiple organ failures). Univariate analysis demonstrated the following significant unfavorable risk factors: age over 1 year at diagnosis (58/108 pts, p = 0.006), NSE > 100 ng/ml (26/95 pts, p < 0.0001), Ferritin > 300 ng/ml (19/98 pts, p = 0.007), LDH > 300 (400) U/L, 51/87 pts, p = 0.004), presence of N-myc amplification (17/59 pts, p = 0.001), deletion of the short arm of chromosome 1 (19/74 pts, p < 0.0001) and di/tetraploidy (32/72 pts, p = 0.008). The power of these factors was even stronger in patients with localized disease whereas no significant prediction was observed for stage IV patients. Furthermore a significant correlation of the serological (NSE, ferritin, LDH) and biological factors (N-myc, deletion 1p, di/tetraploidy) was detected in this study. Only NSE was identified as an independent prognostic factor (p = 0.018) whereas no independent factor could be identified within the 3 biological parameters due to their high correlations (Kendall's tau for N-myc and deletion 1p:0.7). However, N-myc (p = 0.005) as well as deletion 1p (p = 0.01) were found significantly more important than di/tetraploidy. CONCLUSIONS: Biological classification of neuroblastomas should be mandatory and be the prerequisite for any risk adapted treatment. One serological and 2 biological factors could be a good standard evaluation to identify neuroblastoma patients at risk.

Adolescent↗