Dose-dependent cytotoxic and mutagenic effects of antineoplastic alkylating agents on human lymphoblastoid cells

The alkylating agents in clinical use as antineoplastics are strongly implicated as human carcinogens on the basis of animal studies and human epidemiologic studies. However, there is little quantitative information on the extent to which exposure to these drugs is mutagenic for normal (non-malignant) cells and the extent to which such mutagenicity correlates with cytotoxicity of these agents. Human lymphoblastoid cells (WIL2-NS) were exposed to graded doses of eight antineoplastic alkylating agents. Cell killing and mutation induction at the hypoxanthine -guanine phosphoribosyltransferase (HPRT) locus were measured by cloning in microplates in the presence and absence of 6-thioguanine. Dose-dependent decreases in survival were used to calculate IC50s for each of the drugs tested. The IC50s, for 1 hr exposure, ranged from 4 x 10(-7) M for nitrogen mustard to 5 x 10(-4) M for busulfan. The eight drugs tested each induced detectable increases in the frequency of mutant cells. The mutagenicity of these agents is correlated strongly with cytotoxicity. However, at equitoxic doses (IC50), the frequency of induced mutants ranged from approximately 3 x 10(-6) for 1,3-bis(2-chlorethyl)-1-nitrosourea (BCNU) to 2 x 10(-5) for busulfan and cisplatin. These results quantitate the dose-dependent cytotoxic and mutagenic effects of these bifunctional alkylating agents on human cells. All are cytotoxic and mutagenic, although their mutagenic efficiency varies.     

Sediment genotoxicity in the Tietê River (São Paulo,Brazil): In vitro comet assay versus in situ micronucleus assay studies

The in vitro comet assay with the permanent fish cell line RTL-W1 and the in situ micronucleus assay using erythrocytes from indigenous tilapia (Oreochromis niloticus) were used to detect genotoxicity in Tietê River sediments (São Paulo, Brazil). Either test was successful in identifying site-specific differences in genotoxicity, with a high correlation between in situ and in vitro results indicating the relevance of the latter even for environmental studies. Discharges from São Paulo city have major impact on genotoxic effects by sediment-bound contaminants; however, overall genotoxicity decreases downstream. The high genotoxic burden of the Tietê River warrants measures to reduce the input of toxic effluents.     

Selective tumor targeting by the hypoxia-activated prodrug AQ4N blocks tumor growth and metastasis in preclinical models of pancreatic cancer.

PURPOSE: The antitumor activities and pharmacokinetics of the hypoxia-activated cytotoxin AQ4N and its metabolites were assessed in several preclinical models of pancreatic cancers. EXPERIMENTAL DESIGN: The cytotoxic effects of AQ4N prodrug and its bioreduced form, AQ4, were tested against multiple human tumor cell lines using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays. Nude mice bearing s.c. or orthotopically implanted human BxPC-3 or Panc-1 tumor cells were treated with AQ4N. Tumor growth inhibition, time to progression/end point, and liver metastasis were evaluated in treatment versus control groups. Plasma and tumor levels of AQ4N and its metabolites were quantitated by liquid chromatography-tandem mass spectrometry. RESULTS: In contrast to AQ4N, the bioreduced AQ4 metabolite displayed potent cytotoxicity in many human tumor lines, including those derived from human pancreatic adenocarcinomas. Single-agent administration of AQ4N significantly delayed tumor growth, progression, and survival in a manner comparable with gemcitabine in multiple pancreatic tumor models in vivo. Survival increases were accompanied by a reduction in incidence and spread of liver metastasis. Quantitation of AQ4N and its metabolites in tumor-bearing mice showed that the prodrug is rapidly cleared from the circulation by 24 h and neither of the bioreduced metabolites was detected in plasma. In contrast, AQ4N readily penetrated BxPC-3 tumors and the cytotoxic AQ4 metabolite rapidly accumulated in tumor tissues at high levels in a dose-dependent fashion. CONCLUSION: AQ4N undergoes rapid and selective conversion into the potent antineoplastic metabolite AQ4 in tumors in vivo and provides proof of principle for the use of hypoxia-activated prodrugs in the treatment against pancreatic cancers.     

Comparison of lithium concentrations in red blood cells and plasma in samples collected for TDM, acute toxicity, or acute-on-chronic toxicity

Background Lithium salts (Li+) are still one of the most appropriate treatments in manic-depressive disorders. Since Li+ has a narrow therapeutic index, plasma levels must be closely monitored to verify maintenance pharmacotherapy, to prevent side effects, to evaluate compliance and to avoid increasing rates of relapse. Although it has been reported that Li+ concentrations in red blood cells (RBC) should be a better indicator of brain levels, therapeutic drug monitoring (TDM) of Li+ is not based on its routine assessment.Objective The aim of this retrospective study was to compare Li+ concentrations in RBC and plasma and the calculated ratio (LiR= RBC/plasma concentrations) in the three groups of patients.Methods During the past 3 years, 309 Li+ measures were collected corresponding to 165 patients classified into three subgroups (TDM, acute or acute-on-chronic intoxication). Li+ plasma (Cplasma) and RBC (CRBC) concentrations were determined by atomic absorption spectrophotometry.Results Results showed that Li+ concentrations in plasma are significantly correlated to Li+ concentration in RBC (r=0.81, P<0.0001). Although a wide inter- and intra-variability was found, Cplasma, CRBC and LiR were statistically different in the three groups. Compared with TDM, Cplasma was more elevated in cases of acute intoxication whereas Li+ accumulated preferentially in RBC in cases of acute-on-chronic intoxication.Conclusion This study shows the interest of determining Li+ in RBC and plasma for TDM, and that LiR could be a sensitive marker of intoxication and of Li+ impregnation.     

Reflexphotometrische Untersuchungen zur Gelbfärbung des Schädeldaches bei Diabetes mellitus

Zusammenfassung Die farbvalenzmetrische Untersuchung von 34 Diabetikerschädeln ergab beim Vergleich mit 56 Kontrollfällen den gleichen Farbton und die gleiche spektrale Sättigung. Bei den Schädeln der Diabetiker ließ sich jedoch eine verminderte Helligkeit nachweisen. Die Farbänderung ist daher für eine Vermutungs-diagnose Diabetes mellitus mit Recht zu verwenden. Es wird jedoch vorgeschlagen, nicht mehr von einer Gelbfärbung, sondern von einer Dunklerfärbung zu sprechen. Das Ausmaß der dunkleren Färbung ist eindeutig positiv zur Krankheitsdauer korreliert. Frühestens nach 6 Jahre bestehendem Diabetes ist eine signifikante Farbänderung zu erwarten. Die Ursache dieser Farbänderung ist unbekannt. In Modellversuchen mit ikterischen Schädeln konnte gezeigt werden, daß die farbmetrischen Kurven bei in vivo entstandenem Ikterus und bei künstlich durch Gallenflüssigkeit erzeugter Verfärbung prinzipiell gleich verlaufen.

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Reflex photometric studies of the yellow discoloration of the calvaria in diabetes mellitus

Summary The shade of color and the spectral saturation of the calvariae of 34 diabetic patients were the same colorimetrically as those of 56 control cases. The calvariae of the diabetics showed, however, a reduced brightness. Consequently, the color change may rightfully be used for the presumptive diagnosis of diabetes mellitus. It is suggested, however, that one should not refer anymore to a yellow discoloration, but instead to a darker discoloration. The degree of the darker color is clearly correlated directly with the duration of illness. The earliest a significant color change may be expected is after six years of diabetes. The cause of the color change is unknown. In model experiments it could be shown, that the colorimetric curves of calvariae discolored by icterus during life are principally the same as the curves of calvariae discolored artificially with bile.

     

Continuous tissue pH measurement on the fetus during delivery.

Tissue pH values of 70 fetuses have been measured continuously during labor using the micro-electrode designed by Stamm. Significant correlation between continuous tissue pH and corresponding micro blood values can be shown. However, the relationship between patterns of tissue pH and capillary pH values seems not to be very constant. Therefore, the reliability of individual tissue pH measurements is still questionable.     

Biological and chemical determination of dioxin-like compounds in sediments by means of a sediment triad approach in the catchment area of the river Neckar

To evaluate the sediment quality of selected sites in the catchment area of the River Neckar, an integrative assessment approach was used to assess the ecological hazard potential of dioxin-like sediment compounds. The approach is based on 7-ethoxyresorufin-O -deethylase (EROD) induction in embryonic chicken liver culture and comprehensive chemical analyses of polycyclic aromatic hydrocarbons (priority PAHs according to the US Environmental Protection Agency). The majority of the sediment extracts exhibited high potencies as EROD-inducers. In one sediment sample, which was influenced by a sewage treatment plant, a very high concentration of 930 ng bioassay 2,3,7,8-tetrachlorodibenzo-p -dioxin (TCDD) equivalents (bio-TEQs )/g organic carbon could be determined. However, in none of the samples, more than 6% of the EROD-inducing potency could be explained by the PAHs analyzed chemically. Thus, non-analyzed compounds with EROD-inducing potency were present in the extracts. A fractionation of sediment samples according to pH allowed to localize the major part of EROD-inducing compounds in the neutral fractions. However, a significant portion of the EROD induction could also be explained by the acidic fractions. Following the concept of the Sediment Quality Triad according to Chapman, in situ alterations of macrozoobenthos were examined. A comparison of the results predicted by the EROD assay and chemical analyses with alterations in situ , as measured by means of the saprobic index and the ecotoxicological index according to Carmargo, revealed a high ecological relevance of the results of bioassays and chemical analyses for major sites.