Biomedical subjects

Luitpold Distel

Publications and source records attributed to Luitpold Distel.

12 recordsLinked to original sources

PubMed2006

Breakpoint locations within chromosomes 1, 2, and 4 of patients with increased radiosensitivity.

The exposure to low LET-radiation leads to a relative homogeneous distribution of initial damage at the DNA. Subsequent repair and post-repair mechanisms might lead to a selection of specific breakpoint locations along chromosomes. Cells from patients with increased radiosensitivity may have more specific breakpoints due to impaired repair mechanisms. We tested whether cells from patients with increased radiosensitivity had an increase in specific breakpoint clusters. Structural chromosomal aberrations of in vitro irradiated lymphocytes from 11 healthy individuals and another 3 patients with increased radiosensitivity were examined. The chromosome pairs 1, 2, and 4 were treated using the three-color FISH technique. The breakpoints were analyzed by means of computerized imaging software. In total, 1752 chromosomal breakpoints had been considered, 498 from healthy individuals, and 1254 from patients with increased radiosensitivity. For both groups there was a non-homogeneous breakpoint distribution along the chromosomes and a trend towards increased breaks in the telomere-proximal region. Also, both groups had distinct locations with increased breaks. No evidence for significant breakpoint patterns across all patients with increased radiosensitivity was found.

Chromosome Aberrations↗

PubMed2006

Tumor-infiltrating cytotoxic T cells but not regulatory T cells predict outcome in anal squamous cell carcinoma.

PURPOSE: Tumor-infiltrating lymphocytes (TIL) are a possible prognostic factor in solid tumors. Cytotoxic TILs are generally considered as prognostically favorable, whereas regulatory T cells (Treg) may have adverse effects by virtue of their ability to inhibit effector cells. We have evaluated the effect of T-cell subsets on survival in patients with anal squamous cell carcinoma following radiochemotherapy. METHODS: Biopsy specimens from 38 patients with anal carcinomas were evaluated using tissue microarrays and immunohistochemistry for the presence of tumor-infiltrating immune cells using CD3, CD4, CD8, and CD68 antibodies. Treg were identified using an antibody directed against the transcription factor FoxP3, and granzyme B served as a marker for cytotoxic cells. Intratumoral immune cells were enumerated using a semiautomatic image analysis program. Prognostic effect of TIL subsets was evaluated by the log-rank test comparing no evidence of disease survival for groups with high and low numbers using median values as cutoff. RESULTS: CD3+ and CD4+ TILs influenced no evidence of disease survival: 3-year rates for patients with low numbers were 89% and 95%, respectively, and 54% (P = 0.02) and 48%, (P = 0.01), respectively, in cases with high numbers. Large numbers of tumor-infiltrating granzyme B+ cytotoxic cells had a significant negative prognostic effect (P = 0.008), whereas no effect was observed for Treg. CONCLUSIONS: TILs were identified as negative prognostic indicators in anal squamous cell carcinomas with granzyme B+ cytotoxic cells showing highest effect on outcome. This is possibly explained by the selection of therapy-resistant tumor cell clones. No prognostic influence of Treg was found. Knowledge of local immune responses is important for the development of immunotherapeutic strategies.

Anus Neoplasms↗

PubMed2006

Molecular verification of stereotactic radiotherapy in rats using ATMpS1981 immunofluorescence.

BACKGROUND AND PURPOSE: Stereotactic radiation therapy and radiosurgery (STS) might be useful for focused treatment in orthotopic tumor models or to evaluate normal tissues. Spatial accuracy of dose-delivery is crucial and needs to be proven. This study intended to show on a molecular level precision of STS using the radiation activated molecule phospho-serine 1981-ATM (ATMpS1981). PATIENTS AND METHODS: Wistar rats underwent MRI fused with CT for treatment with a NOVALIStrade mark (BrainLab) STS device. Rats (body weight = 350 g, respectively) were irradiated with 2 Gy to selected areas of the brain, the lung, the liver, and the pancreas. Animals were sacrificed 1h after STS and organs were explanted for pathohistological workup. Coronal HE-stained sections of treated organs were matched with coronal MRI and CT reconstructions and isodose distributions of STS. Immunofluorescence signal expression in the nuclei after incubation with anti-ATMpS1981 antibody was compared to the target volume of STS. RESULTS: Three consecutive animals were treated with STS using 2 Gy single dose which resulted in no apparent changes on HE staining but obvious immunofluorescence signals in irradiated regions. In concordance with isodose distributions these signals had a maximum intensity within the 90% isodose and gradually decreased to a background level with very low nuclear immunofluorescence signals for ATMpS1981. These results were consistent throughout all of the four investigated organs (brain, lung, liver, pancreas) and could be repeated in all of the investigated animals. CONCLUSIONS: ATMpS1981 immunofluorescence confirms accuracy of STS allowing for partial organ irradiation in small animals. It can be used for quality assurance in STS treatment of normal tissue or orthotopic tumor models.

Animals↗

PubMed2006

Combined effect of tumor necrosis factor-alpha and ionizing radiation on the induction of apoptosis in 5637 bladder carcinoma cells.

BACKGROUND AND PURPOSE: Apoptosis can be induced by distinct but overlapping pathways. Ionizing radiation induces apoptosis by an "intrinsic", mitochondria-dependent pathway. Ligation of tumor necrosis factor-(TNF-)alpha, FAS (CD95) or TRAIL receptors are typical representatives of an extrinsic, death-receptor-mediated pathway. In this study the effect of irradiation, treatment with the cytokine TNF-alpha, or a combination of both on the induction of apoptosis and clonogenic survival of bladder carcinoma cells was investigated. MATERIAL AND METHODS: 5637 bladder carcinoma cells were treated with different concentrations of recombinant TNF-alpha (0-10 ng/ml), irradiated with single doses ranging from 0.5 to 10 Gy, or a combination of both modalities. Apoptotic cells were quantified by the TUNEL assay up to 96 h following treatment, clonogenic cell survival by a clonogenic assay. Synergistic effects of both modalities were evaluated using isobolographic analysis. RESULTS: Irradiation of 5637 carcinoma cells resulted in a discontinuous dose dependence of the apoptotic fraction with a pronounced increase in the range of 0-2 Gy and a slighter increase at 2-10 Gy. The percentage of apoptotic carcinoma cells also increased continuously after treatment with lower concentrations of TNF-alpha reaching a plateau at concentrations of 5.0-10.0 ng/ml. Isobolographic analysis revealed a supraadditive interrelationship between irradiation and TNF-alpha in the range between 0.005 and 0.5 ng/ml, and an additive effect for TNF-alpha concentrations>0.5 ng/ml. The additive effects were confirmed in clonogenic survival assays with reduced survival fractions following combined TNF-alpha administration and irradiation. CONCLUSION: The combination of two apoptosis-inducing modalities resulted in a synergistic effect on the induction of apoptosis in 5637 bladder carcinoma cells. Although a radiosensitizing effect still has to be proven in animal models, combined-modality treatment may increase the therapeutic effectiveness of irradiation in bladder cancer.

Apoptosis↗

PubMed2006

[Transferrin conjugates in the anticancer therapy].

To enhance the therapeutic efficiacy of anticancer drugs and reducing its systemic side-effects carriers are used. Transferrin is one of the very promising protein which can be used to transport drugs, DNA and ions into the cancer cells. Because of the fact that neoplastic cells have increased number of transferrin receptors, the transferrin can deliver the drugs directly to the neoplastic cells without injury of normal cells.

Animals↗

PubMed2005

Survivin as a radioresistance factor, and prognostic and therapeutic target for radiotherapy in rectal cancer.

Apoptosis levels have been shown to predict tumor response to preoperative radiochemotherapy in rectal cancer. Recently, the prominent role of survivin, a structurally unique member of the inhibitor of apoptosis protein family, has been shown in colorectal cancer tumorigenesis and prognosis. In this study, we investigated whether survivin plays a direct role in mediating radiation resistance. We used short interfering RNA molecules to decrease survivin in radioresistant SW480 and intermediately radioresistant HCT-15 colorectal cancer cells. This resulted in a significant decrease of survivin mRNA and protein expression with a maximum at 24 to 48 hours after transfection. If irradiated during this sensitive period, an increased percentage of apoptotic cells and an increased caspase 3/7 activity in parallel with a decreased cell viability and a reduced clonogenic survival was shown. These effects were more pronounced in the radioresistant SW480 cell line with a radiation-induced cytotoxicity enhancement factor at 10% and 50% survival of 1.8 to 2.2 for SW480 and 1.5 to 1.7 for HCT-15, respectively. Furthermore, transfection with survivin short interfering RNA increased levels of G2-M arrest and levels of DNA double-strand breaks in irradiated cells. These observations indicate that cell cycle and DNA repair mechanisms may be associated with apoptosis induction in tumor cells that are otherwise resistant to killing by radiation. In a translational study of 59 patients with rectal cancer treated with a combination of radiotherapy and chemotherapy, increased survivin expression was inversely related to the levels of apoptosis, and was also associated with a significantly higher risk of a local tumor recurrence.

Adenocarcinoma↗

PubMed2005

Cytogenetic instability in young patients with multiple primary cancers.

Patients younger than 45 years with multiple cancers and a family history of cancer were identified and examined for cytogenetic instability. The cohort included 50 individuals: 19 patients suffering from at least 2 independent cancers, 11 healthy control individuals, a positive control group of 5 highly radiosensitive patients (>grade 3, RTOG), and a tumor control group of 15 patients with a single tumor. Peripheral blood lymphocytes were irradiated in vitro (0.7 Gy, 2.0 Gy). Metaphase chromosomes 1, 2, and 4 were labeled by means of 3-color fluorescence in situ hybridization. Chromosomal aberrations (breaks per metaphase [B/M], complex chromosomal rearrangements [CCR/M]) were analyzed. Very high levels of chromosomal aberrations were detected in a "core group" of 5 patients. These patients displayed much higher rates of B/M and CCR/M than controls. Ten patients had moderately elevated chromosomal aberrations and 4 patients were indistinguishable from controls. We conclude that a significant proportion of young patients with multiple tumors and a family background of cancer display cytogenetic instability.

Adult↗

PubMed2004

Impact of various parameters in detecting chromosomal aberrations by FISH to describe radiosensitivity.

BACKGROUND AND PURPOSE: Analysis of radiation-induced chromosomal aberrations is regarded as the "gold standard" for classifying individual radiosensitivity. A variety of different parameters can be used. The crucial question, however, is to explore which parameter is suited best to describe the differences between patients with increased radiosensitivity and healthy individuals. PATIENTS AND METHODS: In this study, five patients with severe radiation-induced late effects of at least grade 3, classified according to the Radiation Therapy Oncology Group (RTOG), and eleven healthy individuals were examined retrospectively. Peripheral blood lymphocytes were irradiated in vitro with 0.7 Gy and 2.0 Gy prior to cultivation and stained by means of three-color fluorescence in situ hybridization (FISH). The detailed analysis was focused on the number of breaks per metaphase, on breaks from complex chromosomal rearrangements per metaphase, as well as on the percentage of translocations, dicentric chromosomes, breaks, and excess acentric fragments-each in comparison with the total number of mitoses analyzed. RESULTS: Using the number of breaks from complex chromosomal rearrangements after 2.0 Gy, radiosensitive patients as endpoint were clearly to be distinguished (p = 0.001) from healthy individuals. Translocations (p = 0.001) as well as breaks per metaphase (p = 0.002) were also suitable indicators for detecting differences between patients and healthy individuals. The parameters "percentage of dicentric chromosomes", "breaks", and "excess acentric fragments" in comparison to the total number of mitoses analyzed could neither serve as meaningful nor as significant criteria, since they showed a strong interindividual variability. CONCLUSION: To detect a difference in chromosomal aberrations between healthy and radiosensitive individuals, the parameters "frequency of breaks per metaphase", "complex chromosomal rearrangements", and "translocations" are most suitable.

Adult↗

PubMed2004

Effects of low energy protons on clonogenic survival, DSB repair and cell cycle in human glioblastoma cells and B14 fibroblasts.

BACKGROUND AND PURPOSE: The reaction of human tumor cells and mammalian normal tissue to irradiation with low energy protons and X-rays was examined. MATERIAL AND METHODS: An irradiation facility with a vertical proton beam was set up at the Tandem accelerator at the University of Erlangen. U-138MG human glioblastoma cells and B14 hamster fibroblasts were irradiated with 5.7 and 7.0 MeV protons (LET 7.27 and 6.23 keV/microm) and with 120 kV X-rays. The inactivation was measured by the colony forming assay, induction and repair of DNA double strand breaks (DSB) by constant field gel electrophoresis and cell cycle control by image cytometry. RESULTS: An obvious reduction of the shoulder of the dose effect curve was determined. This effect was more pronounced for the glioblastoma cell line. The RBE at 10% survival was measured as 1.78 +/- 0.09 for glioblastoma cells and 1.18 +/- 0.06 for B14 fibroblasts. The induction of DNA DSB in glioblastoma cells showed an RBE of 0.96 +/- 0.06, after 24h repair time an RBE of 2.63 +/- 0.07 was calculated. Protons had a larger and enduring effect on G2 arrest of cell cycle than X-rays, 72 hours after irradiation with 10 Gy an RBE of 1.57 +/- 0.05 was calculated. CONCLUSIONS: The effect of higher LET irradiation was more distinct for tumor cells than for normal tissue. Both cell lines showed a higher RBE for cell survival than the value of 1.1 normally used for proton therapy. Repair capacity of DNA DSB was reduced following low energy proton irradiation and G2 arrest was induced to a larger degree. Further experiments are needed to elucidate if this could be a reason for lower cell survival.

Cell Cycle↗

PubMed2003

Fatal toxicity following radio- and chemotherapy of medulloblastoma in a child with unrecognized Nijmegen breakage syndrome.

BACKGROUND: In large-scale pediatric chemo- and radiotherapy trials a proportion of patients as high as 10-15% is usually reported as having severe treatment related toxicity occasionally resulting in toxic death. Little is known on the underlying predisposition of the individual child. Several hereditary disorders including immunodeficiency (ID) syndromes or repair disorders, Ataxia Telangiectasia (AT), and Nijmegen breakage syndrome (NBS) were associated with an elevated risk for severe treatment related toxicity. PROCEDURE: This report involves the case of a 7-year-old boy with medulloblastoma who suffered from remarkably severe side effects during and after postoperative radio- and chemotherapy. Several months following craniospinal radiation with a total dose of 36 Gy, late normal tissue side effects were observed within the treated volume. Eighteen months after initiation of treatment the patient died due to protracted cardiopulmonary failure. RESULTS: To quantify the intrinsic radiation sensitivity, lymphoblastoid cells were used to examine chromosomal aberrations by fluorescence in situ hybridization detecting between two to ninefold higher chromosomal breakage rates in comparison to cells of average cancer patients. Skin fibroblasts showed in the clonogenic survival assays a twofold increased sensitivity. Western blotting demonstrated a typical lack of Nbs1. PCR-SSCP analysis followed by direct sequencing of positive samples revealed a homozygous truncating mutation of the NBS1 gene (657del5). CONCLUSIONS: This case highlights that severe treatment related complications in pediatric cancer patients may be the result of increased intrinsic radio- and chemosensitivity due to NBS, AT, and other ID syndromes. It is suggested to exclude such conditions in all patients with anthropometric parameters below the 3rd centile and other signs suggestive for repair disorders or ID syndromes.

Abnormalities, Multiple↗

PubMed2003

Significant increase in residual DNA damage as a possible mechanism of radiosensitization by gemcitabine.

PURPOSE: To investigate the effect of gemcitabine (dFdC), a promising radiosensitizing nucleoside analog, on the induction and repair of DNA double-strand breaks (dsbs) after ionizing radiation (RT) in a pancreatic tumor cell line. MATERIAL AND METHODS: BxPC3 pancreatic tumor cells were treated using different concentrations of gemcitabine with and without subsequent irradiation. DNA dsbs were detected by constant-field gel electrophoresis under neutral conditions. RESULTS: With the addition of gemcitabine (0.5-1,000 micromol/l for 2 h prior to RT) to RT (0-75 Gy), a considerable and dose-dependent increase of remaining DNA damage after 24 h (5.4-fold for 0.5 micromol/l dFdC, 12.2-fold for 1,000 micromol/l dFdC at 25 Gy) was noted. Enhancement factors were inversely correlated with increasing X-ray dose (7.8-fold for 0.5 micromol/l at 1 Gy decreasing to 1.6-fold at 75 Gy). Conversely, the induction of DNA dsbs was not affected. Gemcitabine alone lead to a slight increase of initial DNA dsbs and only a modest elevation of residual DNA damage. CONCLUSION: These findings strengthen the hypothesis of DNA repair inhibition as a major mechanism of radiosensitization by gemcitabine.

Antimetabolites, Antineoplastic↗

PubMed2003

Imbalance between proliferation and apoptosis may be responsible for treatment failure after postoperative radiotherapy in squamous cell carcinoma of the oropharynx.

To assess the prognostic value of apoptosis, proliferation and clinical factors in squamous cell carcinoma of the oropharynx after radical surgery and postoperative radiotherapy (RT). Between 1985 and 1995, a total of 82 patients with 84 tumors were entered onto the study. Forty-two primary tumors (50%) involved the tonsils, 23 (27%) the soft palate, and 19 (23%) the base of the tongue. Median age was 52 years (range, 36-73 years). The pT- and pN-categories (UICC 1997) were: T1 (24), T2 (36), T3 (18), T4 (6), N0 (31), N1 (12), N2 (38), NX (8). Histologically clear margins were achieved in all patients by initial surgery. Postoperative RT to the primary and regional lymphatics was given with 60 Gy in 6 weeks and single daily fractions of 2 Gy. The expression of the nuclear Ki-67 labeling index (LI) was investigated by immunostaining using the monoclonal antibody MIB 1 and apoptotic carcinoma cells were identified using the terminal deoxynucleotidyltransferase-(TdT)-mediated dUTP nick end labeling (TUNEL) technique. Median follow-up was 43 months (range, 14-132 months). Overall survival, disease-free survival, and locoregional tumor control rates were 59, 70 and 76% at 5 years. Median values for apoptotic index and Ki-67 labeling were 1.6% (range 0-4.7%), and 20% (range, 0-79%), respectively. Apoptotic index 47 days: 55%, P=0.03), Ki-67 LI ( 20%: 56%, P=0.006). A significant prognostic impact on locoregional control was noted for the duration of RT (P=0.01), tumor site (P=0.02), and the Ki-67 LI (P=0.02). A low apoptotic index together with higher proliferation rates led to unfavourable local control as low as 25% compared to the patients with higher apoptotic index (70-80%, P=0.009). An imbalance between apoptotic index and proliferation may identify patients with squamous cell carcinoma at high risk for local recurrence after surgery and postoperative RT. Prospective observation of these factors in clinical trials is warranted to further elucidate this phenomenon.

Adult↗