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Biomedical subjects

J Fuchs

Publications and source records attributed to J Fuchs.

At least 19 recordsLinked to original sources
PubMed1997

Induction of DNA crosslinks and DNA strand lesions by cyclophosphamide after activation by cytochrome P450 2B1.

Cyclophosphamide requires metabolic activation by cytochrome P450 to exert its genotoxic effects. Therefore in vitro studies on its mechanism of action have been limited to the use of self-activating derivatives of cyclophosphamide or to hepatocytes as an activating system. In this study we used a cell line of Chinese hamster lung fibroblasts (V79 cells), genetically engineered to express active cytochrome P450 2B1 as the sole observable cytochrome P450 (SD1 cells). An increase in DNA strand lesions (SL: DNA single-strand breaks and alkali labile sites) was observed between 0.5 and 1.5 mM cyclophosphamide (24 h incubation) which could be classified as alkali labile sites using a modified alkaline elution assay. Compared to cyclophosphamide, its active metabolite 4-hydroperoxycyclophosphamide (4-OOH-CY) was about 250-fold more effective in induction of SL. Equimolar concentrations of phosphoramide mustard (50 microM), the ultimate DNA binding metabolite of cyclophosphamide, caused only about 50% of SL compared to 4-OOH-CY. A minimum of 12 h of incubation of SD1 cells was needed for cyclophosphamide (1 mM) until SL were detectable, compared to only 2 h for 4-OOH-CY and 1.5 h for phosphoramide mustard (50 microM). DNA crosslinks were observable after shorter incubation periods than single-strand breaks (6 h for cyclophosphamide and 1 h for 4-OOH-CY and phosphoramide mustard) and were no longer detectable at incubation periods of more than 20 h. Treatment of SD1 cells with ionizing radiation only, cyclophosphamide only, and radiation plus cyclophosphamide showed that SL induced by cyclophosphamide were not repaired during incubation with fresh culture medium (24 h). However, an efficient repair of SL caused by ionizing radiation was observed and was not inhibited by cyclophosphamide. These observations give strong evidence that different types of SL were induced by cyclophosphamide and radiation. SD1 cells were able to repair the special kind of SL induced by radiation but not the SL caused by cyclophosphamide.

Animals↗
PubMed1997

Analysis of DNA single-strand breaks in human venous blood: a technique which does not require isolation of white blood cells.

For DNA strand break analysis in human white blood cells, usually metrizoate-Ficoll centrifugation is used to isolate mononuclear cells. This procedure is time-consuming and requires at least 20 ml of blood per sample. Therefore, we developed a technique which does not require isolation of white blood cells prior to DNA strand break analysis by alkaline elution (direct method). The sensitivity of this new technique was compared to that of the standard method, which includes isolation of mononuclear blood cells. A statistically significant increase in sensitivity was observed using the direct method. After in vitro gamma-irradiation of venous blood, an increase in the elution rate of 7.7 x 10(-3) hr(-1)/Gy was detected if mononuclear blood cells were isolated compared to 10.5 x 10(-3) hr(-1)/Gy with the new technique (P < 0.05). Incubation of venous blood with ethylene oxide for 1 hr caused an increase in the elution rate of 5.8 x 10(-3) hr(-1)/mM ethylene oxide for the standard and 12 x 10(-3) h(-1)/mM for the direct method (P < 0.05). DNA single-strand breaks were detected in blood cells of 10 persons without any apparent genotoxic exposure. A mean normalized elution rate of 1.30 +/- 0.38 (95% confidence interval) was detected in isolated mononuclear blood cells, and a similar mean normalized elution rate of 1.41 +/- 0.50 was obtained using the direct method. The difference was not statistically significant. Five patients treated with a combination chemotherapy consisting of cyclophosphamide (750 mg/m2 i.v.), doxorubicin (50 mg/m2 i.v.), vincristine (1.4 mg/m2 i.v.), and prednisolone (100 mg/m2 p.o.) for non-Hodgkin's disease were analyzed for DNA single-strand breaks before and 16-18 hr after the application of chemotherapy. Increases in mean elution rate of 68% and 116% were detected using the standard and the direct methods, respectively. For the direct method, only 3 ml of venous blood were sufficient for analysis of one sample, compared to 25 ml needed if mononuclear cells were isolated, and about 4 hr of work per assay can be saved.

Blood↗
PubMed1997

Benign papilloma of the cervix in childhood: immunohistochemical findings and review of the literature.

UNLABELLED: Papillomas of the genital region are rare benign tumours causing sanguineous vaginal discharge in prepubertal girls. We report on a papilloma of the cervix in a 2-year-old girl. We characterize the tumour immunohistochemically and give a brief review about the current literature. CONCLUSION: Genital tract papillomas are benign differentiated tumours of probable Müllerian origin with a good prognosis even after tumour recurrence. Local excision is adequate for treatment.

Age of Onset↗
PubMed1997

Electron paramagnetic resonance studies on nitroxide radical 2,2,5,5-tetramethyl-4-piperidin-1-oxyl (TEMPO) redox reactions in human skin.

Electron paramagnetic resonance (EPR) is currently being explored for the study of living biological systems. Among biophysical and biochemical applications, the study of nitroxide radical interactions with tissue antioxidants and oxidants is of growing interest. Skin is a target organ of the EPR methodology and is frequently exposed to oxidative stress. We investigated the piperidine-type nitroxide 2,2,5,5-tetramethyl-4-piperidin-1-oxyl (TEMPO) because it is skin permeable and readily accepts electrons in biological systems. TEMPO is readily scavenged on the surface of cultured human skin. Pretreatment of skin cultures with butylhydroperoxide, which decreases intracellular ascorbate and glutathione, causes inhibition of nitroxide scavenging. Exposure of skin cultures to dehydroascorbate, which is internalized and converted to ascorbate, leads to stimulation of nitroxide scavenging. In human keratinocytes and fibroblasts, the TEMPO radical is reversibly reduced to the hydroxylamine depending on the oxygen concentration and the availability of intracellular glutathione and ascorbate. Cell exposure to the glutathione synthetase inhibitor buthionine-sulfoximine depleted intracellular glutathione and inhibited nitroxide reduction; exposure to dehydroascorbate or glutathione-monoethylester increased intracellular ascorbate or glutathione concentration and stimulated nitroxide reduction. Quantitative considerations indicate that the major reduction site of TEMPO in skin and skin cells is the cytosol ascorbate/glutathione redox cycle. We suggest that analysis of TEMPO radical scavenging by the EPR technique is a convenient method for measuring skin ascorbate and thiol-dependent antioxidant activity in vitro and in vivo.

Antioxidants↗
PubMed1997

Retroperitoneal lymphangiomyoma in an infant.

Lymphangiomyomatosis (LAM) is a benign tumor-like lesion of lymphatic vessels with unknown etiology. 80 cases of LAM are presently described. So far, it appears that only women in their reproductive years seem to be affected. Here, we describe the first LAM in an 11-months-old infant with a presumably local form of LAM. This leads us to consider the possibility that this tumor-like lesion may originate from a hamartomateous malformation. The diagnosis is based on pre-operative sonography and CT, as well as on histological and immunohistochemical examination of the tumor.

Female↗
PubMed1996

Chromosome 'painting' in plants - a feasible technique?

It is shown that chromosome painting is as yet not possible for plants with very complex genomes, neither intra- nor interspecific. The reasons are inefficient blocking of dispersed repetitive sequences and insufficient signal intensity of short unique sequences. Future perspective are indicated.

Biotin↗
PubMed1996

Primary DNA damage in peripheral mononuclear blood cells of workers exposed to bitumen-based products.

The genotoxic effect of occupational exposure to bitumen-based products was determined by the extent of DNA strand breaks and alkali-labile sites of the DNA of peripheral mononuclear blood cells from seven roofers, 18 road paving workers, and nine bitumen painters. In order to evaluate short-term genotoxic effect the workers were investigated on Fridays and on Mondays after a weekend free of occupational exposure. The roofers (all cigarette smokers) showed a significantly (P < 0.002) 43% higher mean level of alkaline DNA strand breaks on Friday than did the ten smoking controls included in this study. Also, comparison of the individual levels of alkaline strand breaks on Mondays and on Fridays revealed a significant increase (P < 0.05, Wilcoxon test) during the work week. In the road paving workers and the bitumen painters no statistically significant difference in the mean levels of alkaline strand breaks could be found compared to controls either for the measurement on Mondays or for that on Fridays. However, interesting tendencies were observed. As in the group of roofers, the mean level of alkaline DNA strand breaks as well as the majority of the individual levels of alkaline strand breaks of road paving workers was higher on Fridays than on Mondays. In contrast, bitumen painters exhibited a relatively high level of alkaline DNA strand breaks on Mondays and a decreased mean level of strand breaks on Fridays. DNA adducts could be detected at a low level (up to 2.9 adducts per 10(9) bases) in 10 of 14 road paving workers and bitumen painters using the 32P-postlabelling assay. The number of DNA adducts correlated with the years spend in the present job. Road paving workers and bitumen painters showed only suggestive evidence for a possible genotoxic effect due to their occupational exposure. Because we cannot exclude the formation of DNA cross-links in these workers, a more detailed investigation of the hazard is urgently needed. For roofers, substantial genotoxic damage in peripheral mononuclear blood cells was observed in this study.

Adult↗
PubMed1996

[A disease substitution index: construction and validation].

Empirical research dealing with health and illness often has the problem that the data sets contain a variety of health related variables but no variables abou the appearance of diseases and complaints. In order to solve this problem a disease substitution index (DSI) based on data of the German Socio-Economic Panel (GSOEP, 1985) and the national health survey conducted in the framework of the German Cardiovascular Prevention Study (GCP, 1984-1986) was constructed. Consisting of the variables "medical attendance", "hospital attendance" "existence of chronical diseases" the DSI shows statistically significant association with a series of diseases and complaints. These findings indicate that the DSI can be used to substitute diseases and/or complaints in datasets with the mentioned variables but no informations about diseases or complaints.

Adult↗
PubMed1996

How do Alliaceae stabilize their chromosome ends in the absence of TTTAGGG sequences?

The Arabidopsis-type telomeric repeats (5'-TTTAGGG-3) are highly conserved. In most families of different plant phyla they represent the basic sequence of telomeres that stabilize and protect the chromosome termini. The results presented here show that Alliaceae and some related liliaceous species have no tandemly repeated TTTAGGG sequences. Instead, their chromosomes reveal highly repetitive satellite and/or rDNA sequences at the very ends. These apparently substitute the original plant telomeric sequences in Alliaceae. Both sequence types are very active in homologous recombination and may contribute to the stabilization of chromosome termini via compensation of replication-mediated shortening.

Allium↗
PubMed1996

In situ localization of yeast artificial chromosome sequences on tomato and potato metaphase chromosomes.

In situ localization of short low- or single-copy sequences is still difficult in plants. One solution to this problem could be the use of large yeast artificial chromosomes (YACs) for fluorescence in situ hybridization. Two YACs specific for a single copy marker on the long arm of the NOR-chromosome 2 of tomato (Lycopersicon esculentum) were selected. Both probes hybridized exclusively to this chromosome, although one produced a slightly dispersed hybridization signal. Hybridization of these YACs onto potato chromosome showed a clear single locus on the homoeologous potato chromosome in both cases.

Chromosome Mapping↗
PubMed1996

The effect of medroxyprogesterone acetate and clomiphene citrate on platelet function in menopausal women.

OBJECTIVE: We sought to determine if antiestrogens such as clomiphene citrate (CC) and medroxyprogesterone acetate (MPA) affect platelet activity in postmenopausal patients before and after treatment with estrogens. METHODS: Using an incubation study, we analyzed the effects of CC and MPA on adenosine diphosphate and adrenaline-induced platelet aggregation and on the release of adenosine triphosphate in postmenopausal patients, using a platelet study, we analyzed the effect of these drugs on platelet function. RESULTS: Platelets were inhibited by MPA and CC in the incubation study but not significantly affected in the platelet study. Platelets previously incubated with estrogen were less inhibited by CC than by MPA. DISCUSSION: Thus, platelet study to determine the optimal combination therapy for menopausal patients has indicated that CC has a non-significantly less beneficial in vitro effect on platelet function than MPA.

Adenosine Diphosphate↗
PubMed1996

Successful transplantation of human hepatoblastoma into immunodeficient mice.

Six hepatoblastomas (HBs) from pediatric patients were transplanted into immunodeficient NMRI nu/nu mice. Cells from two fetal HBs did not develop tumors. In contrast, xenografts derived from three nonpretreated HBs and one HB after three courses of chemotherapy, all comprising embryonal cells, showed growth after 8 to 10 weeks. The take rates of HB varied from 60% to 90% (mean, 80%). Histologically, they resembled their originals in the pattern of fetal and embryonal differentiated areas and contained hematopoietic foci. The tumors produced high levels of alpha-feto-protein in the patients and the animals. In contrast to the patients, tumor-bearing mice did not display elevated platelet counts. During serial grafting, growth rates of the tumors gradually increased, and hematopoiesis was no longer detectable; however, histologically, a dedifferentiation could not be clearly identified. The addition of viable human or murine fibroblasts to inoculated cells of three nude mouse HBs resulted in a significant increase in the growth rate of all tumors and reappearance of hematopoiesis in three of the examined 10 xenografts of one HB. The authors conclude that HB xenografts in immunodeficient mice are a feasible in vivo model for studies of the biological behavior of this tumor.

Animals↗
PubMed1996

One-stage reconstruction of bladder exstrophy.

From 1984 to 1990 a primary one-stage reconstruction of bladder exstrophy was performed at our hospital on 15 consecutive infants. Reconstruction included Cohen's ureteral reimplantation, bladder neck reconstruction according to Young-Dees, bladder closure, symphyseal bone approximation, abdominal wall closure, and repair of epispadias in females. Postoperatively, all patients were immobilized by overhead extension. Iliac osteotomy was done in 9 children, but was abandoned in recent years for infants less than one month old Follow-up examinations included an interview with the parents, clinical examinations, blood and urine analyses, uroflowmetry, and ultrasound scan of the abdomen. Nuclear renal scan, i.v. pyelography, and cystography were carried out as indicated. At the time of last evaluation the children were between 3 and 9 years of age. The cosmetic results were satisfactory in all cases. Eight of 15 children were dry day and night with micturition intervals more than 3 hours during day time (complete continence). Five children were dry during day time with micturition intervals up to 3 hours, but occasionally wet their beds (partial continence). Two children were incontinent. Eleven of 15 children had a bladder capacity of more than 100 ml. Renal function was normal in all patients. Two children showed a mild VUR, and no other abnormalities of the upper urinary tracts were found. Iliac osteotomy did not influence the functional or cosmetic results, but in two patients asymmetry of pelvic bones with consecutive lumbar scoliosis was found. Comparing these results with reports on staged reconstructive procedures, we conclude that by primary complete one-stage reconstruction a well acceptable success rate is achieved, and that by this method possibly some advantages are offered to patients with bladder exstrophy.

Bladder Exstrophy↗
PubMed1996

Transient increase in DNA strand breaks in car refinishing spray painters.

OBJECTIVES: Genotoxic risk was evaluated for spray painters possibly exposed to polyester resins and acrylic enamel-based paints in automotive body repair shops. METHODS: DNA (deoxyribonucleic acid) strand breaks and alkali-labile sites were measured in peripheral mononuclear blood cells ex vivo using the alkaline elution method. Samples of venous blood were taken on Monday after a free weekend and again on Friday from 38 male and 1 female spray painters and compared with the blood samples from 36 male and 3 female referents. The elution rate of each DNA sample was standardized by dividing it by the elution rate obtained from simultaneously sampled untreated Chinese hamster V79 cells. RESULTS: The spray painters showed a significantly (P < 0.001) higher mean level of strand breaks and alkali-labile sites in the Friday samples [2.05 (SE 0.17)] compared with the Monday samples [1.38 (SE 0.07)]. The Monday results of the spray painters were not distinguishable from the referents' [1.41 (SE 0.10)]. The increase in DNA damage was numerically higher, but only weakly significant (use of masks, P < 0.05) or nonsignificant (use of spray booths), when fewer safety provisions were taken. CONCLUSIONS: A significant increase in DNA strand breaks and alkali-labile sites was found in spray painters after a week's work. However, DNA damage seems to be reversible. The use of modern safety equipment seems to affect DNA damage only marginally. There is an urgent need to identify the genotoxic chemicals in the occupational environment of spray painters and to develop corresponding satisfactory safety measures.

Acrylic Resins↗
PubMed1996

[Surgical strategy in pediatric liver malignancies].

The therapeutic results of two groups of children with liver tumours were compared: group 1 [29 hepatoblastomas (HB) and five liver carcinomas (HCC)] were operated before 1987, and group 2 (88 HB and 16 HCC) were treated according to the studies HB 89 and HB 94 of the GPOH from 1988 onwards. Resection rates for HB were 81% (group 1) and 93% (group 2), with tumour-free survival rates of 38% and 77%, respectively: anatomic liver resections were more often radical than atypical tumour resections. Resections of lung metastases and liver transplantations increased tumour-free survival. In HCC therapeutic results were equally poor (25% cure). Thus in HB combined chemotherapy and surgery is highly effective, but HCCs are cured only by radical resections.

Carcinoma, Hepatocellular↗
PubMed1995

Decrease of red cell membrane fluidity and -SH groups due to hyperglycemic conditions is counteracted by alpha-lipoic acid.

Human red cell membranes (ghosts) were treated by 5 min of incubation with fasting or hypo- and hyperglycemic concentrations of D-glucose. This simulation of nondiabetic or diabetic conditions revealed an influence on membrane fluidity and on protein -SH reactivity. Protein -SH groups, measured with Ellman's reagent, generally behave in the same way as membrane fluidity determined with diphenylhexatriene. Maximal values were obtained with 5 mM D-glucose, whereas decrease was observed above 10 mM D-glucose. Addition of alpha-lipoic acid (4 nmol/mg protein) resulted in a significant increase in membrane fluidity and titratable -SH groups at glucose concentrations of 10 mM and above. Dithiothreitol diminished titrable-SH groups and did not restore membrane fluidity. 2-Mercaptopropionylglycine was only effective in restoration of -SH groups. By contrast to D-glucose, other sugars such as L-glucose, D-fructose, or sucrose revealed no comparable changes on membrane fluidity and titratable membrane -SH groups between concentrations of 5 and 10 mM. The hyperglycemic effects of D-glucose were corroborated with isolated, reconstituted membrane proteins and erythrocyte glucose carrier, indicating that, in general, the observed divergent biochemical/biophysical changes of the red cell membrane are influenced by the glucose transport protein GluT1. The natural R-form and the S-form of alpha-lipoic acid were compared with racemic R-/S-forms for their efficiencies in alterations of red cell membrane fluidity. Decreased fluidities in presence of 10 mM glucose were found to be influenced in differentiated ways: the S-form was highly active in increasing fluidity at 4 nmol/mg and increasingly less active up to 20 nmol/mg protein. By contrast the R-form of lipoic acid was moderately efficient in increasing fluidity through a larger concentration range between 4 and 80 nmol/mg protein.

Dithiothreitol↗