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A comprehensive definition introducing the term "modified mycotoxins" to encompass all possible forms in which mycotoxins and their modifications can occur was recently proposed and has rapidly gained wide acceptance within the scientific community. It is becoming increasingly evident that exposure to such modified mycotoxins due to their presence in food and feed has the potential to pose a substantial additional risk to human and animal health. Zearalenone (ZEN) is a well-characterized Fusarium toxin. Considering the diversity of modified forms of ZEN occurring in food and feed, the toxicologically relevant endocrine activity of many of these metabolites, and the fact that modified forms add to a dietary exposure which approaches the tolerable daily intake by free ZEN alone, modified forms of ZEN present an ideal case study for critical evaluation of modified mycotoxins in food safety. Following a summary of recent scientific opinions of EFSA dealing with health risk assessment of ZEN alone or in combination with its modified forms, uncertainties and data gaps are highlighted. Issues essential for evaluation and prioritization of modified mycotoxins in health risk assessment are identified and discussed, including opportunities to improve exposure assessment using biomonitoring data. Further issues such as future consideration of combinatory effects of the parent toxin with its modified forms and also other compounds co-occurring in food and feed are addressed. With a particular focus on ZEN, the most pressing challenges associated with health risk assessment of modified mycotoxins are identified and recommendations for further research to fill data gaps and reduce uncertainties are made. [ABSTRACT FROM AUTHOR]

Purpose: The antimalarial drug artesunate (ART) is a promising candidate for cancer treatment as it displays anticancer effects in various models. While in short-term treatment of malaria, an excellent safety profile has been found for ART, the potential long-term treatment of cancer patients demands a phase I dose-finding clinical trial determining the daily ART dose which would be well tolerated as add-on therapy. Methods: Patients with metastatic breast cancer were to receive either 100 or 150 or 200 mg oral ART daily as add-on to their guideline-based oncological therapy for a study period of four weeks with frequent clinical and laboratory monitoring until 4-8 weeks thereafter. According to the statistical design, recruitment was scheduled in groups of three patients in order not to miss a more than 33% frequency of dose-limiting adverse events (DL-AE) prior to dose escalation. Results: Twenty-three patients were recruited, and all planned dose levels were applied. During the actual trial period of 4 ± 1 weeks, three patients experienced six DL-AEs altogether (leucopenia, neutropenia, asthenia, anemia) possibly related to ART (not exceeding 33% in any dose level). Conclusions: Up to 200 mg/d (2.2-3.9 mg/kg/d) oral ART were safe and well tolerated; therefore, 200 mg/d are recommended for phase II/III trials. Safety monitoring should include reticulocytes, NTproBNP, as well as audiological and neurological exploration. [ABSTRACT FROM AUTHOR]

Purpose: Artesunate (ART) has been used for a long time in the treatment of Plasmodium falciparum malaria and has been considered safe. The present phase I study aimed to determine the daily dose of ART that is well tolerated as add-on therapy in patients with breast cancer for 4 weeks of therapy. Ototoxicity could be a potential safety concern in settings different from malaria. Therefore, comprehensive audiological assessment was essential.Methods: The ARTIC M33/2 study was a prospective, open, uncontrolled, monocentric phase I dose-escalation study to evaluate the safety and tolerability of ART in patients with advanced breast cancer. Patients received either 100, 150 or 200 mg oral ART daily for a test phase of 4 weeks as add-on therapy to their ongoing oncological treatment. For the investigation of the safety of ART for hearing, an audiological assessment was performed with each patient before the intake of ART and after 4 weeks of therapy.Results: Twenty-three female patients were included in the study. During the test phase, four patients had adverse events (AEs) of the auditory system possibly related to the intake of ART. However, none of these AEs was classified as severe AE (SAE) and did not require treatment interruption. Four patients had AEs concerning the vestibular system (vertigo) during the test phase, one of which was classified as SAE. However, the SAE was fully reversible after discontinuation of ART.Conclusion: None of the audiological results after 4 weeks of therapy with ART showed any dose-limiting auditory toxicity. However, audiological monitoring in further clinical studies with prolonged use of oral ART in doses up to 200 mg daily is warranted. The ARTIC M33/2 study is registered at eudract.ema.europa.eu with the Number 2007-004432-23 and at clinicaltrials.gov with the Number NCT00764036. [ABSTRACT FROM AUTHOR]

Polymorphisms in genes involved in DNA repair, steroid hormone biosynthesis/metabolism/signaling, folate metabolism as well as cell growth are prime candidates for possible associations with breast and ovarian cancer risk in women with an inherited predisposition. We investigated 29 polymorphisms in 20 genes encoding key proteins of the above four biological pathways for their breast and ovarian cancer risk modifying effect in Polish women harboring BRCA1 founder mutations. Of the analyzed genes, ERCC2, XRCC1, XRCC2, XRCC3 and Lig4 participate in DNA repair, TP53 in cell cycle check point control, AIB1, AR, COMT, CYP11A1, CYP17A1, CYP19A1, HSD17 and PGR in steroid hormone biosynthesis/metabolism/signaling, TYMS in folate metabolism and HER2, IL6, LRP1, TGFB and TGFBR1 affect cell growth. Using validated methods, we genotyped 319 breast cancer cases, 146 ovarian cancer cases and 290 unaffected controls, all of whom harbored one of three causative mutations in BRCA1. Our results revealed no association of any of the investigated polymorphisms with BRCA1-associated breast or ovarian cancer risk. Thus, it appears that these polymorphisms do not influence disease risk in Polish women carrying one of the three common BRCA1 founder mutations. [ABSTRACT FROM AUTHOR]

The purpose of this trial was to compare the feasibility of adjunctive intrapleural instillation of antimicrobial or antibiotic solutions in parapneumonic empyema. Patients receiving video-assisted thoracic surgery for parapneumonic empyema stage II were prospectively randomized to either of the following groups: group I (8 patients), postoperative irrigation treatment with Ringer solution; group II (8 patients), instillation of 200 ml Taurolidin 2%: group III (8 patients), instillation of Neomycin/Bacitracin twice a day. Treatment could be given as planned in 8 patients in group I, 6 patients in group II, and 5 patients in group III. No statistically significant differences were obtained when comparing the two groups II and III with Ringer group I. The median chest tube drainage time in group I: 12.5 days, in group II: 13.5 days, and group III: 25 days. The median irrigation duration was 9.5 days in group I, 12.5 days in group II, and 20 days in group III. Postoperative instillation and irrigation of antimicrobial or antibiotic solutions is a feasible method to achieve local cleansing in patients with parapneumonic empyema thoracis. Chest tube drainage time, irrigation duration, and hospitalization time were not improved under Taurolidin or Neomycin/Bacitracin compared with Ringer solution. [ABSTRACT FROM AUTHOR]

Progressive muscle wasting is a central feature of cancer-related cachexia and has been recognized as a determinant of poor prognosis and quality of life. However, until now, no easily assessable clinical marker exists that allows to predict or to track muscle wasting. The present study evaluated the potential of myoglobin (MG) plasma levels to indicate wasting of large locomotor muscles and, moreover, to reflect the loss of MG-rich fiber types, which are most relevant for daily performance. In 17 cancer-cachectic patients (weight loss 22%) and 27 age- and gender-matched healthy controls, we determined plasma levels of MG and creatine kinase (CK), maximal quadriceps muscle cross-sectional area (CSA) by magnetic resonance imaging, muscle morphology and fiber composition in biopsies from the vastus lateralis muscle, body cell mass (BCM) by impedance technique as well as maximal oxygen uptake (VO2max). In cachectic patients, plasma MG, muscle CSA, BCM, and VO2max were 30–35% below control levels. MG showed a significant positive correlation to total muscle CSA ( r = 0.65, p < 0.001) and to the CSA fraction formed by type 1 and 2a fibers ( r = 0.80, p < 0.001). However, when adjusted for body height and age by multiple regression, MG yielded a largely improved prediction of total CSA (multiple r = 0.83, p < 0.001) and of fiber type 1 and 2a CSA (multiple r = 0.89, p < 0.001). The correlations between CK and these muscle parameters were weaker, and elevated CK values were observed in 20% of control subjects despite a prior abstinence from exercise for 5 days. In conclusion, plasma MG, when adjusted for anthropometric parameters unaffected by weight, may be considered as a novel marker of muscle mass (CSA) indicating best the mass of MG-rich type 1 and 2a fibers as well as VO2max as an important functional readout. CK plasma levels appear to be less reliable because prolonged increases are observed in even subclinical myopathies or after exercise. Notably, cancer-related muscle wasting was not associated with increases in plasma MG or CK in this study. [ABSTRACT FROM AUTHOR]

Background and Purpose: The role of radiochemotherapy in the treatment of primary glioblastoma multiforme is still discussed controversially. To evaluate the feasibility and toxicity of irradiation and concomitant administration of 50 mg/m(2) temozolomide in patients with primary malignant glioma, this phase I/II study was conducted.Patients and Methods: 53 Patients with histologically confirmed WHO grade IV malignant glioma were enrolled into the study. All patients were treated with radiation therapy up to a total dose of 60 Gy using conventional fractionation of 5 x 2.0 Gy/week. Temozolomide was administered orally each therapy day at a dose of 50 mg/m(2).Results: Prior to radiochemotherapy, complete resection (n = 14), subtotal resection (n = 22) or a biopsy (n = 17) of the tumor was performed. The median time interval between surgery and radiochemotherapy was 21 days. Treatment-related toxicity was very mild. Acute toxicity > grade 2 was observed in one patient who developed grade 4 hemotoxicity. Minor side effects of chemotherapy included nausea and vomiting. No severe late effects were observed. Median progression-free and overall survival were 8 and 19 months, respectively. The overall survival rate was 72% at 1 and 26% at 2 years. Age and extent of surgery significantly influenced survival.Conclusion: The combination of temozolomide plus radiation therapy is feasible and safe in terms of toxicity. Overall survival times were relatively long compared to survival times reported for radiotherapy alone. The application of 50 mg/m(2) of temozolomide can be performed throughout the whole time course without interruption due to side effects and might largely contribute to the prolonged overall survival. Further evaluation is warranted as to which dose of temozolomide is optimal with regard to tumor response and toxicity. [ABSTRACT FROM AUTHOR]

Insulin signaling is enhanced by moderate concentrations of reactive oxygen species (ROS) and suppressed by persistent exposure to ROS. Diabetic patients show abnormally high ROS levels and a decrease in insulin reactivity which is ameliorated by antioxidants, such as N-acetylcysteine (NAC). A similar effect of NAC has not been reported for non-diabetic subjects. We now show that the insulin receptor (IR) kinase is inhibited in cell culture by physiologic concentrations of cysteine. In two double-blind trials involving a total of 140 non-diabetic subjects we found furthermore that NAC increased the HOMA-R index (derived from the fasting insulin and glucose concentrations) in smokers and obese patients, but not in nonobese non-smokers. In obese patients NAC also caused a decrease in glucose tolerance and body fat mass. Simultaneous treatment with creatine, a metabolite utilized by skeletal muscle and brain for the interconversion of ADP and ATP, reversed the NAC-mediated increase in HOMA-R index and the decrease in glucose tolerance without preventing the decrease in body fat. As the obese and hyperlipidemic patients had lower plasma thiol concentrations than the normolipidemic subjects, our results suggest that low thiol levels facilitate the development of obesity. Supplementation of thiols plus creatine may reduce body fat without compromising glucose tolerance. [ABSTRACT FROM AUTHOR]

The clinical outcome of spinal cord injury (SCI) depends in part on the extent of secondary damage, to which apoptosis contributes. The CD95 and tumor necrosis factor (TNF) ligand/receptor systems play an essential role in various apoptotic mechanisms. To determine the involvement of these ligands in SCI-induced damage, we neutralized the activity of CD95 ligand (CD95L) and/or TNF in spinal cord-injured mice. Therapeutic neutralization of CD95L, but not of TNF, significantly decreased apoptotic cell death after SCI. Mice treated with CD95L-specific antibodies were capable of initiating active hind-limb movements several weeks after injury. The improvement in locomotor performance was mirrored by an increase in regenerating fibers and upregulation of growth-associated protein-43 (GAP-43). Thus, neutralization of CD95L promoted axonal regeneration and functional improvement in injured adult animals. This therapeutic strategy may constitute a potent future treatment for human spinal injury. [ABSTRACT FROM AUTHOR]

Aging-related loss of muscle function is a predictor of mortality and a surrogate parameter of the aging process. Its consequences include a high risk for falls, hip fractures, and loss of autonomy. Aging is associated with changes in the oxidant/antioxidant balance including a decrease in plasma thiol (cysteine) concentration. To assess the importance of cysteine, we determined in a double-blind study the effects of N-acetylcysteine on the functional capacity of frail geriatric patients and their response to physical exercise. The subjects on placebo showed only a relatively weak response, and 31% showed even a decrease in more than one parameter during the observation period. Low plasma arginine levels were correlated with a weak overall performance before exercise and a poor response to exercise. N-Acetylcysteine strongly enhanced the increase in knee extensor strength and significantly increased the sum of all strength parameters if adjusted for baseline arginine level as a confounding parameter. N-acetylcysteine had no significant effect on growth hormone and IGF-1 levels but caused a significant decrease in plasma TNF-α. These findings may provide a basis for therapeutic intervention and suggest that the loss of function involves limitations in cysteine and one or more other amino acids which may compromise muscular protein synthesis. [ABSTRACT FROM AUTHOR]

To determine the therapeutic effect of sulfur amino acid supplementation in HIV infection we randomized 40 patients with antiretroviral therapy (ART; study 1) and 29 patients without ART (study 2) to treatment for 7 months with N-acetyl-cysteine or placebo at an individually adjusted dose according to a defined scheme. The main outcome measures were the change in immunological parameters including natural killer (NK) cell and T cell functions and the viral load. Both studies showed consistently that N-acetyl-cysteine causes a marked increase in immunological functions and plasma albumin concentrations. The effect of N-acetyl-cysteine on the viral load, in contrast, was not consistent and may warrant further studies. Our findings suggest that the impairment of immunological functions in HIV+ patients results at least partly from cysteine deficiency. Because immune reconstitution is a widely accepted aim of HIV treatment, N-acetyl-cysteine treatment may be recommended for patients with and without ART. Our previous report on the massive loss of sulfur in HIV-infected subjects and the present demonstration of the immunoreconstituting effect of cysteine supplementation indicate that the HIV-induced cysteine depletion is a novel mechanism by which a virus destroys the immune defense of the host and escapes immune elimination. [ABSTRACT FROM AUTHOR]

Dermatologic, ophthalmologic, and neurologic examinations were carried out on 33 patients with clinical symptoms of xeroderma pigmentosum (XP). Complementation groups were determined for 23 patients. Types of tumors and complementation group were found to be related in the following way: In the XP variant groups basaliomas were the most frequently occurring malignant tumors, whereas in the D group pigmentary tumors, such as melanotic precanceroses and melanomas prevailed; in the A and the C group, spinaliomas seem to be the most frequent malignomas. The DNA repair activity was measured using colony-forming ability and unscheduled DNA synthesis. Colony-forming ability was quantitated as a function of 12 different UV doses and expressed in terms of D. Unscheduled DNA synthesis was determined autoradiographically by establishing dose-response curves, which analyzed by the characteristic value of linear regression. G, defined as the linear increase in the mean number of silver grains per nucleus when the UV dose is multiplied by the factor of e (i. e., 2.72), was derived from the slopes of the regression lines. The repair capability of XP fibroblast lines was classified on the basis of D and G. [ABSTRACT FROM AUTHOR]

2, 3, 7, 8-Tetrachlorodibenzo- p-dioxin (TCDD) has been shown to inhibit uroporphyrinogen decarboxylase activity resulting in chronic hepatic porphyria. From a cross-sectional study of 170 workers in chemical industry 68 showed elevated coproporphyrin levels, interpreted as secondary coproporphyrinuria. Three persons suffered from chronic hepatic porphyria in subclinical stages. None of the workers showed an overt porphyria cutanea tarda. A lowgrade zinc protoporphyrinemia was observed in three persons. Forty-three of the 170 workers were evaluable for investigating the effect of TCDD on porphyrin levels. No significant correlation was found between TCDD concentration in adipose tissue and the level of uroporphyrin and coproporphyrin. The influence of a chloracne history is described. [ABSTRACT FROM AUTHOR]

DNA polymerases α, δ and ε from normal regenerating rat liver and Novikoff hepatoma cells were purified about 300-fold, characterized, and checked for sensitivity towards drugs known to inhibit cell proliferation. Characterization included (a) identification of associated proteins, (b) measurement of physicochemical constants (including sedimentation coefficients, diffusion coefficients, calculation of relative molecular masses), (c) quantification of catalytic activities using specific DNA primer templates ( K values) and specific inhibitors ( K values), and (d) discrimination between DNA polymerases from normal cells and those from malignant cells using inhibitors of cell proliferation. (a) DNA primase associated with DNA polymerase α, and 3′-5′ exonuclease accompanying DNA polymerases δ and ε had similar activities. (b) Comparison of physicochemical and catalytic properties of DNA polymerases from both sources revealed similarities but also some important differences. Sedimentation and diffusion coefficients of DNA polymerases α and ε from malignant cells differed significantly. (c) The DNA-binding domain of DNA polymerases α and ε from hepatoma cells was altered since K values, determined with several specific DNA primer-templates, were higher. Furthermore, dNTP-binding sites of DNA polymerases from malignant cells; when probed with specific inhibitors (aphidicolin, butylphenyl-dGTP, carbonyldiphosphonate, and dideoxy-TTP) showed significantly lower K values, indicating lower affinity to deoxyribonucleoside 5′-triphosphates. (d) Sixteen drugs representative of various modes of interaction with DNA and protein were chosen. Dose/response experiments were performed and the concentration at which the polymerizing activity was reduced to 50% was calculated ( K values). Preferential inhibition of DNA polymerases α,δ, and ε from Novikoff hepatoma cells was found for: the intercalating drugs doxorubicin, daunorubicin, amsacrine, mitoxantrone, quinacrine and ethidium bromide, the minor-groove binders distamycin and netropsin, the ATPase-blocking agents novobiocin and coumamycin, and the topoisomerase I inhibitors camptothecin and topotecan. When the sensitivity of polymerases δ and ε was measured using poly(dA·dT) as a primer-template, the preferential inhibition of the enzymes from malignant cells was even more pronounced. Drugs known to trap the DNA-topoisomerase-II complex, etoposide, nalidixic acid, teniposide, and merbarone did not affect DNA polymerases irrespective of the source. Since the majority of the inhibitors used, particularly intercalators and minor-groove binders, act by modification of the primer-template, inhibition of DNA synthesis must have occurred through weakening of non-covalent bonds between DNA and catalytic polypeptides. Consequently, preferential inhibition of DNA polymerases from malignant cells seems to be indicative of abnormally diminished binding of the enzymes to their primer-templates. This effect may be caused by conformational alterations in polymerases from malignant cells which affect the DNA binding domains. Similarly, changes in physicochemical and kinetic constants are indicative of alterations of dNTP-binding domains. [ABSTRACT FROM AUTHOR]

The DNA excision repair capacity of 23 primary fibroblast lines from patients with dysplastic nevus syndrome was investigated and DNA repair synthesis ('unscheduled DNA synthesis') was determined after UV exposure. Seventeen fibroblast lines from normal donors served as controls. The dose/response experiments included up to ten dose levels and two wavelength ranges: UV-C (using a low-pressure mercury lamp emitting predominantly 254-nm light) and UV-B (artificial 'sunlamp' radiation centering around 312-nm light). For each dose level, silver grains over fibroblast nuclei were counted by visual inspection. Twelve cell lines were also evaluated for both UV wavelength ranges using a new semi-automatic image analyzing system. This system included components for rapid sequential identification of both fibroblast nuclei and silver grains sited above them. Silver grains over 100 nuclei were determined for each UV dose level. Dose/response curves were established and analyzed by linear regression. As a quantitative term for assessing DNA excision repair capacity of a cell line we calculated the linear increase ( G) in the number of grains per nucleus, when the UV dose was multiplied by the factor e (i.e. 2.72). The sensitivity of grain detection and resolution ofoverlapping grains was approximately threefold better in visual than in automatic counting, especially when there were more than 70 grains over nuclei. The time recуired for visual conting, however, was tenfold that of automatic counting. The varianceweighted mean G of all fibroblast lines from patients with dysplastic nevus syndrome was found to be 79.1 (±1.8-grains/nucleus, that of fibroblast lines from normal donors was 74.2 (±1.7) grains/nucleus. This difference revealed a slightly better repair capability for cell lines from patients but was at the borderline of detection and, therefore, should not be overinterpreted. From the experimental accuracy achieved by determination of the varianceweighted means of the two groups, we would have been able to detect a difference of 7 and more grains [> 2 x (σ + σ)]. The variance-weighted mean G of all fibroblast lines from patients with dysplastic nevus syndrome was found to be 76.4 (±1.4) grains/nucleus, whereas that of fibroblast lines from normal donors was only 66.6 (±1.8) grains/nucleus. This difference was statistically significant and, contrary to expectation, revealed better, not worse post-UV DNA repair capability in cell lines from patients that in those from normal donors. From the experimental accuracy achieved by determination of the variance-weighted means of the two groups, we would have been able to detect a difference of 6.4 or more grains [> 2 x (σ + σ)]. Variation between cell lines belonging to the same group was expressed by the standard deviation. On average, the standard deviation was in the range 18.2-21.1 grains/nucleus. This variation did not reflect experimental inaccuracy but different responses of individual cell lines to UV irradiation. On the basis of our data, we consider the hypothesis that patients with dysplastic nevus syndrome are prone to melanoma development because of a general defect in post-UV DNA repair to be improbable. [ABSTRACT FROM AUTHOR]

The initiation/promotion standard protocol 28 (protocol 28), developed and used previously as an experimental model to verify the cancerogenic process of initiation/promotion in mouse skin, was revised in three aspects: (a) statistically it was shown sufficient to use, per promoter dose group, 16 colony-outbred female NMRI mice: (b) by weekly individual records of tumor response (and health status) of each mouse in a dose group, cumulative tumor incidences (and mean and extreme body weights) are determined; from these data the collective records (tumor response, health status), the only data accessible from protocol 28, may be generated in addition; (c) the details of dose groups and all data on tumor response and health status are processed by computer using the program package PAPILLOM. The latter was developed specifically for this purpose, is written in the programming language APL and designed for easy handling by staff of animal laboratories. The program package calculates, from the individual records per promoter dose group, cumulative tumor incidences (and survival data) with confidence limits for any one exposure time, and the package may be linked to programs for statistical validations. In addition, from the collective records it calculates the tumor rates, tumor yields and survival rates for any one exposure time. These data, obtained by either of the standard protocols (16 or 28), are fully comparable. For pure compounds they may be used to calculate semiquantitative tumor-promoting potencies. These values for more than 80 polyfunctional diterpenes of the tigliane, ingenane and daphnane type, scattered in or calculated from previous papers, together with their irritancies, were compiled. Within recent years, computer-assisted standard protocol 16 has been used to handle and evaluate about 1000 promoter dose groups. Protocol 16 allows one to extract and utilize more and better toxicological information on tumor response and health status from any one dose group, utilizing significantly fewer experimental animals than required by protocol 28. Thus, the computer-assisted standard protocol 16 optimizes the utility of the experimental model of mouse skin for the amount, quality and management of experimental data as well as for the requirements of animal protection. [ABSTRACT FROM AUTHOR]

The aim of our work was to investigate whether DNA topoisomerase II participates in the repair-specific incision of UV-irradiated genomic DNA. Therefore, the influence upon DNA incision of the topoisomerase II inhibitors (nalidixic and oxolinic acid, novobiocin and coumermycin A) as well as the intercalating agent quinacrine has been measured in normal human fibroblasts using the alkaline elution technique. In addition, inhibition by novobiocin has been determined in fibroblast strains from 11 normal donors and from 16 xeroderma pigmentosum (XP) patients belonging to the complementation groups A, C, D, E, and XP variant. Nalidixic and oxolonic acid did not inhibit endonucleolytic cleavage, whereas novobiocin was a potent inhibitor of DNA incision. It was observed that in normal and in all XP strains 50% inhibition by novobiocin occurred on average in the dose range 315-590 μ M. Since inhibition by novobiocin was not paralleled by that with the other topoisomerase II inhibitors nalidixic and oxolinic acid, it must be concluded that reduction of enzyme-catalysed breaks was not due to the participation of topoisomerase II in the incision step, but to the displacement of ATP at the binding site of the DNA-incising enzyme. This enzyme absolutely requires ATP as a cofactor for endonucleolytic cleavage. Quinacrine, however, inhibited DNA incision in normal fibroblasts at a mean K of 318 μ M. Inhibition by this intercalating agent seems to be caused by structural perturbations in DNA, which render it a poor substrate for endonucleolytic cleavage. [ABSTRACT FROM AUTHOR]

DNA repair capacity of 18 fibroblast strains from patients with dysplastic nevus syndrome, 5 of them with malignant melanoma, was investigated and their colony-forming ability ( D) after UV exposure was determined as a measurement of this. Seventeen fibroblast strains from normal donors served as controls. The dose/ response experiments included up to 11 dose levels and two UV wavelength ranges: UV-C (using a low-pressure mercury lamp emitting predominantly 254-nm light) and UV-B (artificial 'sunlamp' radiation centering around 312-nm light). The exponential segments of the dose/response curves were analysed by linear regression and the negative reciprocals of the regression coefficients, D, were calculated for each cell strain and each wavelength range. When comparing D values of individual cell strains from patients with and without melanomas with the mean value for all normal donors, only 4 out of 18 showed increased sensitivity towards UV-B. This difference, however, was not statistically significant. On the contrary, weighted-mean D values for fibroblast strains from patients with and without melanoma were found to be slightly but significantly higher than those for normal donors (significance level: 5%), indicating that cell strains from these patients were less sensitive to UV light (UV-C and UV-B) of both wavelength. This result, which on the basis of current literature data is somewhat unexpected, holds true within the limits of experimental accuracy of ±12%. [ABSTRACT FROM AUTHOR]

Fibroblast strains derived from skin biopsies of patients with actinic keratosis (6), malignant melanoma (18), squamous cell carcinoma (11), and basal cell carcinoma (12) were investigated for DNA repair synthesis, with 16 fibroblast strains for normal donors as controls. Cells were exposed to UV light, the 'UV-like' carcinogen (Ac)ONFln, and the methylating carcinogenes MeSOOMe and MeNOUr. Dose-response experiments, which included 10 dose levels, were performed, the data analyzed by linear regression, and the slope of the regression line (term: G) used as a measure of DNA repair synthesis. The mean experimental variability of G of individual fibroblast strains was 9.5%-15.4%, depending upon exposure. For comparison of all cell strains belonging to the same skin malignancy group with those of the control group, G values of the individual strains were combined to yield group-specific weighted mean G values. In addition, the capacity to incise UV-damaged DNA was measured in 24 cell strains from patients with skin tumors using the alkaline elution technique. For quantitating DNA-incising capacity, the initial velocities of the elution curves were plotted versus the UV dose, and the slope of the resulting regression line was used to obtain the characteristic value E. The mean experimental variability of E of individual strains was ±22%. These E values were combined to yield weighted mean values of groups. The fibroblast strains in the groups of patients with actinic keratosis and malignant melanoma were found to have normal mean G values when DNA repair synthesis was challenged with UV light or one of the three carcinogens. However, the squamous cell carcinoma group exhibited significantly lower mean G values after treatment with UV light (82% that of normal donors), (Ac)ONFln (70%), MeSOOMe (70%), and MeNOUr (69%). The basal cell carcinoma group showed significantly diminished repair synthesis upon treatment with UV light (81% that of normal donors) and MeSOOMe (67%). In contrast to these findings, in no skin malignancy group was post UV DNA-incising capacity ( E) significantly diminished, although it should be noted that group sizes were only half as large as for G determinations. These data may be interpreted as indicating that DNA excision repair is impaired in fibroblast strains from patients with squamous cell carcinoma and - to a lesser extent - basal cell carcinoma. This deficiency seems to pertain to several DNA repair mechanisms, as excision of both alkylation and UV-induced damage is involved. Although the repair impairments are statistically significant, the relative risks at which the investigated patients are do not seem to be high enough as to be of immediate practical value. Our results indicate further studies would be useful. [ABSTRACT FROM AUTHOR]

The XP cell strain XP29MA, its malignant counterpart XP29MAmal and a normal human fibroblast strain were tested for colony-forming ability after treatment with HECNU in the presence of mG, mGua, and heG. In XP29MAmal, inhibition of post-HECNU colony-forming ability was 35% when 0.25 mM of either mG or mGua were present, whereas in XP29MA and the normal fibroblast strain no inhibition was detected. The heG caused a similar but smaller inhibitory effect in XP29MAmal, but failed to do so in XP29MA. HECNU predominantly exerts its killing effect by alkylating O-6 of DNA-bound guanine and causing DNA interstrand crosslinks. Alkylation of O-6 of guanine can be repaired by 6-methylguanine-DNA methyltransferase. From our experiments we conclude that in XP29MAmal this methyltransferase was inhibited in the presence of the 6-alkylguanines, thus leaving more 2-chloroethylated sites in DNA unrepaired. This results in sensitization in terms of decreased colony-forming ability observed only in the malignant cell line. [ABSTRACT FROM AUTHOR]

A total of 45 XP fibroblast strains from the Mannheim XP Collection (representatives of XP complementation groups A, C, D, E, F or G, I, and XP variants) were investigated for colony-forming ability (term: D after treatment with up to ten doses of the methylating carcinogen MeSOOMe. As controls 16 fibroblast strains from normal donors were used. Except for 4 XP strains (1 from group C and 3 from group D) which, however, were borderline cases, none of the remaining 41 XP strains was found to be more sensitive than normal controls. This held true within the limits of an experimental accuracy (experimental variability of D values) of ±7%. When weighted means were calculated for XP complementation groups and compared with that of normal donors at a significance level of 5%, no significant difference was detected. In contrast, after exposure of 6 XP group D strains to MeNOUr, a weighted mean D value was obtained which was significantly decreasd by 27%. Unscheduled DNA synthesis (term: G which serves as a measure of excision repair) after exposure to MeNOUr was quantitatively the same (exposure to MeNOUr was quantitatively the same (experimental varability: ±8%) both in the group of normal strains and in most of the XP complementation groups. Exceptions were group E and group F (or G) which had higher, and group I which had lower repair. Analogous G values measured after exposure to MeSOOMe (experimental variability: ±13%), however, differed from that of the control strains: they were lower in XP complementation groups A, D, E, F (or G), and I. However, groups A, E, F (or G), and I including only 3 individual strains or less may be considered to be possibly ill-represented. Yet, group D including 11 XP strains did show reduction of the mean G value by 35%. From this it is concluded that there are repair defects in XP group D strains with regrad to MeSOOMe-induced adducts. These defects seem to be small. [ABSTRACT FROM AUTHOR]

A total of 16 normal and 46 XP fibroblast strains from the Mannheim Collection were investigated for colony-forming ability following exposure to both UV light and the 'UV-like' carcinogen (Ac)ONFln. The dose-response experiments included up to 13 dose levels. The exponential segments of the curves were analysed by linear regression and the negative reciprocal of the regression coefficient (D) was calculated for each cell strain. For quantitating the DNA-incising capacity, DNA elution curves were determined at several UV dose levels. Plotting the initial velocities of the elution curves versus the UV dose yielded a regression line, the slope of which was used to obtain the characteristic value E. Comparing D with E values showed that cell strains in which colony-forming ability was reduced suffered a reduction of DNA-incising capacity of the same magnitude. There were only 3 exceptional strains in which reduction of DNA-incising capacity was less pronounced than reduction of colony-forming ability. We have previouly shown (Fischer et al. 1982) that D values from 27 XP strains of the Mannheim Collection were correlated with clinical symptoms. This correlation is now being extended by relating colony-forming ability to the magnitude of the DNA incision defect. From our data we conclude that the best quantitative biochemical denominator to explain the sun sensitivity of XP is that of a defective incision of UV-damaged DNA. A considerable similarity in sensitivity towards both UV light and (Ac)ONFln was found in 16 normal and 46 XP strains. This seems to indicate that UV-and (Ac)ONFln-induced DNA damage are removed to a large extent by the same pathways in human fibroblasts. [ABSTRACT FROM AUTHOR]

DNA repair capacity was investigated in 25 normal and XP fibroblast lines after UV damage was induced, using the following methods: colonyforming ability, unscheduled DNA synthesis, and alkaline elution (which can serve as a measure of repair-specific DNA incision). The majority of the XP fibroblast lines was derived from biopsies of patients who are at present under clinical observation by Dr. E.G. Jung (Dept. of Dermatology, Mannheim Medical School). Colony-forming ability was determined at 12 different UV dose levels and expressed in terms of D. Unscheduled DNA synthesis was measured autoradio-graphically. Dose-response curves (grains per nucleus versus UV dose) were established and analyzed by linear regression. The characteristic value of G, defined as the linear increase in the mean number of grains per nucleus when the UV dose is multiplied by the factor e (i.e., 2.72), was derived from the slope of the regression lines. For quantitating DNA-incising activity of a cell line, DNA elution curves were determined at several UV dose levels. Plotting of the initial velocities of the elution curves versus the UV doses yielded a regression line, the slope of which was used to obtain the characteristic elution value, E. A descriptive correlation of all three characteristic values, D, G and E, showed that in all cell lines in which colony-forming ability and unscheduled DNA synthesis were diminished, a reduction of DNA-incising activity occurred. We conclude that this reduction accounts for both the decreased colony-forming ability and unscheduled DNA synthesis. [ABSTRACT FROM AUTHOR]

A correction to the article "Long-term outcome and survival of surgically treated supratentorial low-grade glioma in adult patients," published in the September 4, 2009 issue is presented.