Biomedical subjects

D Schwabe

Publications and source records attributed to D Schwabe.

61 records · Page 4Linked to original sources

PubMedDate not supplied

Differential diagnosis based on immunological-phenotyping in suspected malignant bone marrow involvement in childhood.

The diagnostic value of immunophenotyping (IP) as a first-line diagnostic method in diseases that infiltrate the childhood bone marrow (BM) or mimic infiltrated BM was examined. Two hundred and fifty unselected BM samples from 250 children suspected to have a malignancy infiltrating their BM were evaluated by means of IP and conventional morophological-cytochemical (MC) studies. We applied the alkaline phosphatase anti-alkaline phosphatase method for IP using a panel of monoclonal antibodies (Mabs) against leukocyte-associated antigens, neuroectodermal antigens, and intermediate filament antigens. Four cases of neuroblastoma, two cases of Ewing sarcoma, and one case of rhabdomyosarcoma were diagnosed by IP but not by MC studies. In nine cases of acute leukemia bone marrow blasts could not be ascribed to a specific lineage on the basis of blast morphology or histochemistry. Eight samples without morphological evidence of malignant infiltration revealed an increased percentage of immature B cell precursors (CD10+, TdT+) suggesting acute lymphoblastic leukemia. None of these children has developed malignant lymphoproliferative disease. Our data suggest that the immunological evaluation of BM in childhood is highly capable of discriminating between different malignant populations but it does not recognize malignancy and therefore supplements but cannot replace conventional methods for diagnosis.

Adolescent↗

PubMedDate not supplied

Aphidicolin glycinate inhibits human neuroblastoma cell growth in vivo.

Aphidicolin is a fungal derived tetracyclic diterpene antibiotic. It is selectively toxic for neuroblastoma (NB) cells in vitro but has no significant effects on the viability of normal human cells and a variety of other tumor entities. We evaluated the antitumoral effects of the water soluble ester aphidicolin glycinate (AphiG) on established human NB xenografts from UKF-NB-3 cells in athymic (nude) mice. Furthermore, we explored the efficacy of direct intraneoplastic and systemic delivery of AphiG. Systemic administration of AphiG (60 mg/kg intraperitoneally, twice per day on 10 consecutive days) significantly suppressed tumor growth but was not able to induce any cures. In contrast, intratumoral AphiG injections (60 or 40 mg/kg/twice a day for 4 days) induced complete tumor regression. Two weeks after the end of treatment no tumor cells were microscopically detectable. Animals were free of tumor for more than 90 days. Histologic examination of inner organs and bone marrow did not reveal any apparent toxic effects of AphiG. These data strongly indicate that AphiG deserves further evaluation as a specific treatment for neuroblastoma.

Animals↗

PubMedDate not supplied

Bovine seminal ribonuclease inhibits in vivo growth of human neuroblastoma cells.

Bovine seminal ribonuclease (BS-RNase) is a homologue of RNase A with specific antitumor activities. It is selectively toxic for neuroblastoma (NB) cells in vitro with no significant effects on the viability of normal human cells. We evaluated the antitumoral effects of BS-RNase on human NB xenografts from UKF-NB-3 cells in athymic (nude) mice. The efficacy of direct intraneoplastic, subcutaneous and systemic delivery of BS-RNase was explored. Systemic administration of BS-RNase (12.5 mg/kg/day intraperitoneally, for 20 days in the course of four weeks) suppressed tumor growth but was not able to induce any cures. Subcutaneous injections (12.5 mg/kg/day for 20 days in the course of four weeks) and intratumoral BS-RNase treatment using the same schedule resulted in complete tumor regression. During 30 days following cessation of treatment no tumor regrowth was observed and animals were free of tumors. Toxic effects of BS-RNase (e.g., on bone marrow and inner organs) were not apparent. This data indicates that BS-RNase fulfills important criteria for a candidate antitumor agent specific for NB.

Animals↗

PubMedDate not supplied

Bovine seminal ribonuclease exerts selective cytotoxicity toward neuroblastoma cells both sensitive and resistant to chemotherapeutic drugs.

BACKGROUND: Bovine seminal ribonuclease (BS-RNase) exerts selective cytotoxicity toward different types of tumor cells. In the present study, we tested the effects of BS-RNase on cultured neuroblastoma (NB) cells resistant to chemotherapeutic agents. The selectivity of the antitumoral activity of BS-RNase was evaluated using cultures of CD34+ hematopoietic stem cells. MATERIALS AND METHODS: Human NB cell lines including IMR-32, UKF-NB-2 and UKF-NB-3 were selected for resistance against vincristine, doxorubicin or cisplatin by exposure to increasing concentrations of the respective drug. The cytotoxicity of the drugs to NB cells was evaluated using a clonogenic assay in a methylcellulose medium. Peripheral blood progenitor cells were obtained from adult healthy donors by positive selection using specific anti-CD34+ antibodies. The toxicity of BS-RNase to CD34+ cells was assessed in the direct clonogenic assay using methylcellulose medium or in ex vivo expansion culture supplemented with hematopoietic growth factors. RESULTS: In the clonogenic assay it was shown that BS-RNase completely inhibits growth of both parental NB cells and their sublines resistant to chemotherapeutic drugs at concentrations (up to 50 micrograms/ml) which have no significant influence on the growth of colony-forming units, granulocyte macrophage and erythroid burst-forming units. Moreover, BS-RNase had no effect on the ex vivo expansion of total hematopoietic cells or of colony-forming cells from CD34+ progenitors. CONCLUSIONS: BS-RNase is a highly efficient agent against NB cells resistant to chemotherapeutic drugs. The lack of toxicity to hematopoietic progenitor cells suggests that BS-RNase is also likely to have tolerable hematopoietic toxicity.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMedDate not supplied

Selective activity of BS-RNase against anaplastic thyroid cancer.

BACKGROUND: Anaplastic thyroid carcinoma is an aggressive solid tumor that fails to adequately respond to any known chemotherapeutic regimen. The development of effective chemotherapy agents would provide the best chance for long-term survival of patients. MATERIALS AND METHODS: The cytotoxic effects of bovine seminal ribonuclease (BS-RNase) against thyroid carcinoma cell lines with different degrees of differentiation in comparison to non-malignant cells, including human foreskin fibroblasts (HFF) and retinal pigment epithelial cells (RPE), were tested using the MTT dye reduction assay. Induction of apoptosis was demonstrated by annexin V assay and expression of proteins related to apoptosis was investigated by flow cytometry. The antitumoral in vivo effects of BS-RNase were assessed on established xenografts of anaplastic thyroid carcinoma cell line 8505C in nude mice using subcutaneous injections of BS-RNase (12.5 mg/kg once a day, on 20 consecutive days). RESULTS: All the tumor cell lines exhibited marked sensitivity against BS-RNase in comparison to HFF and RPE cells. The greatest growth inhibition was seen in the 8505C line, while IC50 values for papillary (B-CPAP) and poorly-differentiated thyroid carcinoma cells were about 6-fold higher. The cytotoxic action of BS-RNase was associated with induction of apoptosis. Expressions of Fas and Fas-ligand were not influenced by BS-RNase completely, while the down-regulation of Bcl-2 in treated cells was observed. In vivo treatment induced significant tumor regression after the course of 20 consecutive days. No apparent toxic effects of BS-RNase toward non-malignant cells were observed during the in vivo treatment. After cessation of therapy (day 20) tumor volume continued to decrease and the tumor was no longer detectable after 30 days of treatment induction in all animals. CONCLUSION: BS-RNase may have beneficial effects for treatment of aggressive anaplastic thyroid cancer.

Animals↗

PubMedDate not supplied

Increase of fetal hemoglobin synthesis indicating differentiation induction in children receiving valproic acid.

Differentiation induction is a distinct concept in the treatment of malignant diseases, considering that malignant cells share many features with immature progenitor cells that are capable of terminal differentiation. Treatment of tumor cells with short-chain fatty acid treatment of erythroid progenitors in vitro and in vivo induces cellular differentiation resulting in gamma-globin, i.e., fetal hemoglobin synthesis. Valproic acid (VPA) is a branched-chain fatty acid that is able to inhibit growth of human and rodent tumor cells and to induce a mature phenotype. The antitumoral effects observed in preclinical studies were reached at concentrations that are readily achieved in patients treated with VPA for epilepsy. Hypothesizing that anticonvulsive VPA levels may be used for antitumoral differentiation induction therapy of pediatric malignant tumors, the authors studied fetal hemoglobin-inducing capacity of VPA in children treated with VPA for epilepsy. Fetal hemoglobin was significantly increased in 30 children with epilepsy treated with VPA monotherapy for at least 3 months when compared to untreated control patients. Furthermore, fetal hemoglobin levels correlated with VPA serum levels. The study confirms the dose-dependent stimulating effect of VPA on fetal hemoglobin synthesis at anticonvulsive doses. The results suggest that nontoxic VPA levels reached in pediatric epilepsy patients should be capable of inducing cellular differentiation of pediatric malignant tumors for therapeutic purposes. Broad clinical experience with VPA and its low toxicity further encourage the evaluation of VPA in pediatric oncology for differentiation induction therapy.

Adolescent↗

PubMedDate not supplied

Outcome of [131I]metaiodobenzylguanidine therapy of neuroblastoma: seven years after.

Beginning in 1984 and based on a total of 40 treatments with [131I]metaiodobenzylguanidine (131I-MIBG) in most cases with a follow-up of 5 years or more, it seems to be worthwhile reevaluating our clinical data and draw some final conclusions: We treated 12 children with a neuroblastoma (NB) IV and 3 with a NB III. In no case 131I-MIBG was the primary therapy. The great majority suffered from recurrence. The mean treatment interval after chemotherapy was 6 months (range 0-54). We calculated a median cumulative tumor dose of 77 Gy (range 0-259) in patients with stage III and 30 Gy (range 4-267) in stage IV NB. The tumor half-life time of 131I-MIBG does not significantly differ between stage III (3 days) and IV (2-5 days). Although the median tumor dose of stage III NB exceeded that of stage IV, we found in NB IV a significant tumor remission in 7 out of 12 cases. On the other hand, a slight reduction of tumor size was seen in only 1 case of stage III NB. This indicates a lower radiation sensitivity of stage III NB. Despite this fact, the two patients with stage III NB who presented a sufficient 131I-MIBG-tumor uptake turned to become operable after 131I-MIBG. Stage IV patients improved, too, even if most of them suffered from recurrence with a very poor prognosis: 3 patients of stage IV lived longer than 48-60 month or are still alive. However, no one of this group remitted completely.(ABSTRACT TRUNCATED AT 250 WORDS)

3-Iodobenzylguanidine↗