Structural identification and antioxidant activity of trans-9, trans-11, cis-15-conjugated linolenic acid converted by probiotics.

The study aimed to determine the chemical structures of octadecatrienoic acid isomers produced by probiotics through the bioconversion of α-linolenic acid and to assess their antioxidant capacities. The chemical structures were identified using nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (MS), while the antioxidant capacities were evaluated in vitro and in cellular. The NMR signals obtained allowed for definitive characterization, with the main ion fragments detected being m/z 58.0062, 59.0140, 71.0141, 113.0616, 127.0777, and 181.5833. Compounds at concentrations below 40 µM maintained the antioxidant capacity of HepG2 cells by protecting endogenous antioxidative enzymes and mitochondrial membrane potential. However, doses higher than 40 µM increase oxidative damage and mitochondrial dysfunction. These results confirmed the structure of the probiotic-derived compound as trans9, trans11, cis15-conjugated linolenic acid. Additionally, appropriate doses of CLNA can alleviate oxidative stress induced by AAPH, while high doses aggravate cellular damage. These findings provide foundational information for the further exploration of probiotic-derived edible lipids.

The Development of an Extraction Method for Simultaneously Analyzing Fatty Acids in Macroalgae Using SPE with Derivatization for LC-MS/MS.

Fatty acid analysis is an essential step in evaluating the potential of macroalgae for biodiesel production. An extraction method was developed to simultaneously analyze up to five types of biodiesel-fuel-related fatty acids (myristic acid, palmitic acid, cis-palmitvaccenic acid, stearic acid, and oleic acid) in macroalgae using liquid chromatography and tandem mass spectrometry (LC-MS/MS). Lypophilization and solid-phase extraction (SPE) techniques were applied to improve the extraction efficiency and effectively purify samples. The optimal conditions for SPE were set by comparing the recoveries according to the various solvent conditions for each step (loading, washing, and elution). In addition, the introduction of trimethylaminoethyl (TMAE) derivatives to the hydroxyl group of the target analyte increased the ionization efficiency and sensitivity. The derivatized samples were analyzed using the LC-MS/MS method with electrospray ionization in the positive and multiple-reaction monitoring modes. The target analytes were separated and detected within 13.5 min using a CAPCELL PAK C18 MGII S3 column. Gradient elution was performed using distilled water and acetonitrile containing 5 mM ammonium acetate. This method offers a reliable and sensitive tool for the analysis of macroalgae samples for their potential use in biodiesel production. To the best of our knowledge, this is the first report on the simultaneous determination of fatty acids in macroalgae using LC-MS/MS with TMAE derivatization.

LC-MS-based urine metabolomics analysis of chronic subdural hematoma for biomarker discovery.

BACKGROUND: Chronic subdural hematoma (CSDH) is one of the most common neurosurgical diseases with atypical manifestations. The aim of this study was to utilize urine metabolomics to explore potential biomarkers for the diagnosis and prognosis of CSDH. METHODS: Seventy-seven healthy controls and ninety-two patients with CSDH were enrolled in our study. In total, 261 urine samples divided into the discovery group and validation group were analyzed by LC-MS. The statistical analysis and functional annotation were applied to discover potential biomarker panels and altered metabolic pathways. RESULTS: A total of 53 differential metabolites were identified in this study. And the urinary metabolic profiles showed apparent separation between patients and controls. Further functional annotation showed that the differential metabolites were associated with lipid metabolism, fatty acid metabolism, amino acid metabolism, biotin metabolism, steroid hormone biosynthesis, and pentose and glucuronate interconversions. Moreover, one panel of Capryloylglycine, cis-5-Octenoic acid, Ethisterone, and 5,6-DiHETE showed good predictive performance in the diagnosis of CSDH, with an AUC of 0.89 in discovery group and an AUC of 0.822 in validation group. Another five metabolites (Trilobinol, 3'-Hydroxyropivacaine, Ethisterone, Arginyl-Proline, 5-alpha-Dihydrotestosterone glucuronide) showed the levels of them returned to a healthy state after surgery, showing good possibility to monitor the recovery of CSDH patients. CONCLUSION AND CLINICAL RELEVANCE: The findings of the study revealed urine metabolomic differences between CSDH and controls. The potentially diagnostic and prognostic biomarker panels of urine metabolites were established, and functional analysis demonstrated deeper metabolic disorders of CSDH, which might conduce to improve early diagnose of CSDH clinically.

Ganoderma adspersum (Ganodermataceae): Investigation of Its Secondary Metabolites and the Antioxidant, Antimicrobial, and Cytotoxic Potential of Its Extracts.

Ganoderma is a genus of wood-degrading mushrooms with medicinal importance. Most Ganoderma species have been studied extensively for their secondary metabolites, biological activities, and ecological value. In this study, the biological activities of the extracts of G. adspersum growing wild on Morus alba trees in the region of Western Thrace (Greece) were evaluated, and the petroleum ether, dichloromethanolic, and methanolic extracts were studied further for their secondary metabolites. Six substances were isolated by chromatographic (Clumn Chromatography (C.C.), High Performance Liquid Chromatography (HPLC)) and spectroscopic methods (Nuclear Magnetic Resonance (NMR)), which were classified in the following categories: (a) unsaturated fatty acids: cis-oleic acid (1); (b) sterols: ergosta-7,22-dien-3-one (2), ergosta-7,22-dien-3-ol (3), and ergosta-5,7,22-trien-3-ol (4); and (c) lanostane-type triterpenoids: applanoxidic acid G (5) and applanoxidic acid A (6). Finally, the biological activities of the extracts were estimated for their antioxidant, antimicrobial, and cytotoxic potential. The methanolic extract of G. adspersum showed the highest total antioxidant activity. The results of the antimicrobial activities indicated that all of the extracts had a minimum inhibitory concentration (MIC) ranging between 39.1 and 312.5 µg/mL. The evaluation of the cytotoxic activity of the samples showed once again that the methanolic extract was the most potent among the examined extracts, with half-maximal inhibitory concentration (IC50) values of 19.22 µg/mL (Hep2c cells), 32.9 µg/mL (RD cells), and 8.94 µg/mL (L2OB cells). Moreover, the bioactivity scores of the isolated secondary metabolites were calculated using the online computer software program Molinspiration. The compounds showed promising bioactivity scores for drug targets.

Synthesis of trans- and cis-4'-hydroxylomustine and development of validated analytical method for lomustine and trans- and cis-4'-hydroxylomustine in canine plasma.

In veterinary medicine, lomustine has been successfull used primarily for the treatment of resistant lymphoma and also for the treatment of mast cell tumors, intracranial meningioma, epitheliotropic lymphoma, and histiocytic sarcoma in dogs either alone or in combination with other chemotherapeutic agents. Even though lomustine is commonly used in dogs primarily for the treatment of resistant lymphoma, there is no pharmacokinetics information available regarding this compound in dogs. In the present study, we developed and validated a simple high-performance liquid chromatography (HPLC) method with a one-step liquid-liquid extraction procedure to detect and quantify lomustine and its two monohydroxylated metabolites (trans- and cis-4'-hydroxylomustine) in canine plasma for future pharmacokinetic studies. The HPLC-diode-array detection method reported here readily detects lomustine, cis-4'-hydroxylomustine, and trans-4'-hydroxylomustine in canine plasma with a limit of detection of lomustine, cis-4'-hydroxylomustine, and trans-4'-hydroxylomustine in plasma of about 10 ng/120 microL, 5 ng/120 microL, and 5 ng/120 microL, respectively. The mean extraction efficiency values for lomustine, cis-4'-hydroxylomustine, and trans-4'-hydroxylomustine were 73%, 90%, and 89%, respectively, from canine plasma samples on HPLC. The present study also provides stability information about lomustine and its two monohydroxylated metabolites in canine plasma and methanol solution stored at various conditions.

Nitroxyl radicals for labeling of conventional therapeutics and noninvasive magnetic resonance imaging of their permeability for blood-brain barrier: relationship between structure, blood clearance, and MRI signal dynamic in the brain.

The present study describes a novel nonradioactive methodology for in vivo noninvasive, real-time imaging of blood-brain barrier (BBB) permeability for conventional drugs, using nitroxyl radicals as spin-labels and magnetic resonance imaging (MRI). Two TEMPO-labeled analogues (SLENU and SLCNUgly) of the anticancer drug lomustine [1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea] were synthesized, using a substitution of the cyclohexyl part with nitroxyl radical. Nonmodified nitroxyl radical TEMPOL was used for comparison. The nitroxyl derivatives were injected intravenously in healthy mice via the tail vein, and MR imaging of the brain was performed on a 7.0 T MRI. The MRI signal dynamic of SLENU and SLCNUgly followed the same kinetics as nonmodified TEMPO radical. SLENU and SLCNUgly were rapidly transported and randomly distributed in the brain tissue, which indicated that the exchange of cyclohexyl part of lomustine with TEMPO radical did not suppress the permeability of the anticancer drug for BBB. The selected nitroxyl derivatives possessed different hydrophobicity, cell permeabilization ability, and blood clearance. Based on these differences, we investigated the relationship betweenthe structure of nitroxyl derivatives, their half-life in the circulation, and their MRI signal dynamic in the brain. This information was important for estimation of the merits and demerits of the described methodology and finding pathways for overcoming the restrictions.

Nitroxyl radicals as low toxic spin-labels for non-invasive magnetic resonance imaging of blood-brain barrier permeability for conventional therapeutics.

The present study describes a novel non-radioactive methodology for in vivo non-invasive, real-time imaging of blood-brain barrier (BBB) permeability for conventional drugs, using nitroxyl radicals as spin-labels and magnetic resonance imaging (MRI).

Effect of the spin-labelled 1-ethyl-1-nitrosourea on CCNU-induced oxidative liver injury.

This study was carried out to determine the effects of 1-ethyl-3-[4-(2,2,6,6-tetramethylpiperidine-1-oxyl)]-l-nitrosourea (SLENU), recently synthesised in our laboratory, and vitamin E as positive control on 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU) - free radical induced oxidative injuries in the liver of mice. Specifically, alterations in malonyl dialdehyde (MDA) level and activities of some antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT), were measured in liver homogenates from tumour-bearing C57 black mice after treatment with solutions of CCNU (30 mg/kg) and SLENU (100 mg/kg), both administered intraperitoneally. CCNU-induced increase in MDA level, SOD and CAT activities were suppressed by SLENU. The present results and those from a previous report demonstrated superoxide scavenging activities (SSA) of the nitrosourea SLENU and enabled us explain the protective effect of the spin-labelled nitrosourea on CCNU-induced oxidative stress in the liver of mice. This protective effect is through the scavenging of *O2- and by an increased production of *NO. Thus, a potential for developing new combination chemotherapy in cancer is seen.

Evaluation of naphthal-NU, a 2-chloroethylnitrosourea derivative of naphthalimide, as a mixed-function anticancer agent.

Naphthal-NU, 2-[2-[3-(2-chloroethyl)-3-nitrosoureido]ethyl]-1H-benz[de]isoquinoline-1,3-dione (Compound 1) has been synthesized as a rationally designed new mixed-function anticancer agent from 1,8-naphthalic anhydride. Its chemical alkylating activity compared with CCNU as standard compound indicated that it possesses greater alkylating activity than the latter. Its antitumour efficacy was assessed in vivo in two murine ascites tumours namely Sarcoma-180 (S-180) and Ehrlich ascites carcinoma (EAC) by measuring the increase in median survival times (MST) of drug treated (T) over untreated control (C) mice. Three clinical drugs namely CCNU (lomustine), endoxan (cyclophosphamide) and 5-fluorouracil (5-FU) were used as positive controls for comparison. Compound 1 has displayed excellent and reproducible antitumoural activity having curative effects in these tumours comparable with CCNU and 5-FU. It has also significantly increased the life span of mice bearing highly advanced tumour for 10 days before the drug challenge. Its toxicity was also assessed in vivo in normal and in S-180 bearing mice by measuring drug-induced changes in hematological parameters, femoral bone marrow and splenic cellularity sequentially on days 9, 15 and 21 following drug treatment at the optimum dose of 50 mg/kg from day 1 to 7. The results indicated that the compound did not adversely affect hematopoiesis. Drug-induced hepatotoxicity and nephrotoxicity were also evaluated at its optimum dose on those days but no such toxicities were detected. It was further screened in vitro in 6 different human tumour cell lines but no significant activity was observed in those lines.

Spin-labeled 1-alkyl-1-nitrosourea synergists of antitumor antibiotics.

A new method for synthesis of four spin-labeled structural analogues of the antitumor drug 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU), using ethyl nitrite for nitrosation of the intermediate spin-labeled ureas has been described. In vitro synergistic effects of 1-ethyl-3-[4-(2,2,6,6-tetramethylpiperidine-1-oxyl)]-1-nitrosourea (3b) on the cytotoxicity of bleomycin and farmorubicin were found in human lymphoid leukemia tumor cells. We measured the tissue distribution of 3b in organ homogenates of C57BL mice by an electron paramagnetic resonance method. The spin-labeled nitrosourea was mainly localized in the lungs. Our results strongly support the development and validation of a new approach for synthesis of less toxic nitrosourea derivatives as potential synergists of antitumor drugs.

Genotoxic effect of 4-aroyl-1-(2-chloroethyl)-1nitrosohydrazinecarboxamides on Saccharomyces cerevisiae cells.

The study of some 4-aroyl-1-(2-chloroethyl)-1-nitrosohydrazinecarboxamides with a Saccharomyces cerevisiae mutagenicity test of increased sensitivity defined two of them, 4-(4-bromobenzoyl)-1-(2-chloroethyl)-1-nitrosohydrazinecarboxam ide and 4-(4-fluorophenyl)-1-(2-chloroethyl)-1-nitrosohydrazine carboxamide as typical cytostatic agents. At concentrations of 2-5 microg/ml the substances kill up to 60%-70% of cells without having any detectable recombinogenic and mutagenic effects. At the same concentrations, lomustine, well known as a cytostatic reference, demonstrated recombinogenic and mutagenic activity on yeast cells. The advantage of the newly synthesized substances is that, in a certain concentration range, their biological activity is mainly cytotoxic without induction of recombinogenic and mutagenic events in surviving cells.

Improved delivery through biological membranes. XLV. Synthesis, physical-chemical evaluation, and brain uptake studies of 2-chloroethyl nitrosourea delivery systems.

The dihydropyridine in equilibrium with pyridinium redox chemical delivery system (CDS) was supplied to two 2-chloroethylnitrosoureas, i.e., HECNU and CCNUOH, and the physicochemical properties of the delivery systems were studied to assess their potential as improved delivery forms to the CNS. Detailed physicochemical evaluation and brain uptake studies were performed on one of the delivery systems (CCNUOH-CDS) derived from trans-4-hydroxy-CCNU, an active metabolite of CCNU. Two aqueous-based formulations derived from hydroxypropyl-beta-cyclodextrin (HP beta CD) and Tween 80:ethanol:water system were developed for CCNUOH-CDS to overcome the poor aqueous solubility conferred upon it by its high lipophilicity. The formulations enabled a 200- to 400-fold improvement in the water solubility of CCNUOH-CDS. Dose- and vehicle-dependent comparative tissue distribution studies in rats indicated improved brain-to-organ ratios of the delivery system at lower doses.

Improved delivery through biological membranes. XXX. Synthesis and biological aspects of a 1,4-dihydropyridine based chemical delivery system for brain-sustained delivery of hydroxy CCNU.

A redox chemical delivery system based on the NADH in equilibrium NAD+ model was applied to an active metabolite (D) of 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU), i.e. CCNU-OH. The 1,4-dihydrotrigonelline ester of CCNU-OH, N-(2-chloro ethyl)-N'-[trans-4-(1,4-dihydro-1-methyl-3-pyridinecarbonyloxy)cyc lohexyl]- N-nitrosourea (D-CDS) was prepared by a direct hydride transfer reaction of the corresponding pyridinium precursor (D-Q+) with a highly reactive 1-benzyl-1,2-dihydroisonicotinamide. The in vitro kinetics in biological fluids indicated facile oxidative conversion of D-CDS to D-Q+. An in vivo study showed that one intravenous injection to rats of D-CDS resulted in rapid brain accumulation of D-Q+, followed by a sustained release of CCNU-OH, while D-Q+ was rapidly eliminated from systemic circulation. The ratio of brain/blood concentration of D-Q+ was found to increase progressively with time. At an equimolar dose of CCNU-OH, the ratio of brain/blood concentration for CCNU-OH was found to be close to unity.

Energy status in HeLa cells after treatment with an arresting anticancer drug.

The energy status of HeLa cells arrested in the G2 phase of the cell cycle by the antineoplastic agent cis-acid was compared with that of normal G2-phase-synchronized cells. The results showed that treatment with the drug has significantly decreased the adenylate pool, adenylate energy charge and phosphorylation potential.

Prevention of 1-(3-deoxycytidyl),2-(1-deoxyguanosinyl)ethane cross-link formation in DNA by rat liver O6-alkylguanine-DNA alkyltransferase.

Previous studies have shown that the haloethylnitrosoureas introduce the cross-link 1-(3-deoxycytidyl),2-(1-deoxyguanosinyl)ethane into DNA. This structure is evidently formed by the following sequence of events: an initial attack of a haloethyl group on the O6 position of guanine, formation of the reactive intermediate, 1,O6-ethanoguanine, and reaction of this intermediate with deoxycytidine in the opposite DNA strand. To investigate the role of O6-alkylguanine-DNA alkyltransferase in preventing the formation of this cross-link, a DNA substrate containing O6-fluoroethylguanine has been prepared by reacting DNA with N-2-fluoroethyl-N'-cyclohexyl-N-nitrosourea. The O6-fluoroethylguanine content of this substrate decreases when it is incubated at 37 degrees C and pH 7.8 in the absence of repair factors because of the chemical instability of O6-fluoroethylguanine; however, this loss is accelerated by the addition of rat liver O6-alkylguanine-DNA alkyltransferase, indicating that this repair factor recognizes and repairs O6-fluoroethylguanine in DNA; furthermore, by using [chloroethyl-14C]N-chloroethyl-N'-cyclohexyl-N-nitrosourea, it can be shown directly that the addition of rat liver O6-alkylguanine-DNA alkyltransferase prevents 1-(3-deoxycytidyl),2-(1-deoxyguanosinyl)ethane formation. These studies link the presence of repair activity to the prevention of a specific cytotoxic lesion in DNA.

DNA sequence selectivity of guanine-N7 alkylation by three antitumor chloroethylating agents.

The DNA sequence selectivities of guanine-N7 alkylation produced by three chloroethylating antitumor agents, 1-(2-chloroethyl)-3-(cis-2-hydroxy) cyclohexyl-1-nitrosourea (cis-2-OH CCNU), 2-chloroethyl (methylsulfonyl)methanesulfonate, and 8-carbamoyl-3-(2-chloroethyl)imidazo-[5,1-d]-1,2,3,5-tetrazin-4(3H )-one (mitozolomide), were examined using a modification of the Maxam and Gilbert sequencing technique. In a region of pBR322 DNA, 2-chloroethyl (methylsulfonyl)methanesulfonate produced approximately the same degree of alkylation at all guanines. cis-2-OH CCNU, however, preferentially alkylated the middle guanines in runs of three or more guanines; the intensity of the reaction increased with the number of adjacent guanines in the DNA sequence. Mitozolomide produced the same pattern of preferential alkylation but not as intensely as cis-2-OH CCNU. Three other nitrosoureas, 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea, 1-(2-fluorethyl)-3-cyclohexyl-1-nitrosourea, and 1-(2-chloroethyl)-1-nitrosourea gave similar patterns of alkylation to that of cis-2-OH CCNU at pH 7.2. The ratio of 7-hydroxyethylguanine to 7-chloroethylguanine was approximately the same following treatment of the synthetic polymers dGn X dCn and (dG X dC)n with cis-2-OH CCNU, indicating that 7-chloroethylation and 7-hydroxyethylation were enhanced similarly by the presence of adjacent guanines. Ethylnitrosourea produced relatively little alkylation preference. The results suggest that the alkylating intermediates, 2-chloroethyldiazohydroxide and 2-hydroxyethyldiazohydroxide, tend to react preferentially with those guanine-N7 positions the electronegativity of which is enhanced by the presence of neighboring guanines. This is consistent with the presence of cationic character in the alkylating centers of these intermediates. 2-Chloroethyl (methylsulfonyl)methanesulfonate and ethyldiazohydroxide would not be expected to have strong cationic character, in agreement with their lack of sequence selectivity.

2-Chloroethyl (methylsulfonyl)methanesulfonate (NSC-338947), a more selective DNA alkylating agent than the chloroethylnitrosoureas.

The novel chloroethylating agent 2-chloroethyl (methylsulfonyl)methanesulfonate (CIEtSoSo) has been shown to act like the chloroethylnitrosoureas (CIEtNu's) in its DNA damaging and cytotoxic effects in human cell lines and has similar activity to the CIEtNu's in the National Cancer Institute antitumor screening tests. Its simpler chemistry, however, suggests that it may alkylate DNA more selectively than do the CIEtNu's. The DNA base adducts produced in calf thymus DNA by CIEtSoSo have been compared to a representative, non-carbamoylating CIEtNu, 1-(2-chloroethyl)-3-(cis-2-OH)cyclohexyl-1-nitrosourea, using high-pressure liquid chromatography. Two major modified base peaks were observed from the nitrosourea treated sample which have been subsequently identified by high-pressure liquid chromatography comparison of synthesized standards and by electron impact gas chromatography/mass spectrometric analysis to be 7-hydroxyethylguanine and 7-chloroethylguanine. In contrast only 7-chloroethylguanine was obtained from the CIEtSoSo treated DNA at equimolar doses. Thus CIEtSoSo was found to be more specific in its reaction with DNA in that it produced less variety of products than the nitrosourea, with no apparent generation of hydroxyethyl products, which are major side reactions of the CIEtNu's.

Emergence of nitrosourea resistant sublines of Lewis lung tumour following MeCCNU treatment in vivo.

Several different drug retreatment protocols were employed to examine the emergence of resistance to MeCCNU in Lewis lung tumours. Previous studies suggested that although the majority of cells in untreated Lewis lung tumours were sensitive to MeCCNU, there was a very small proportion of resistant cells (approximately 0.001%) that limited "tumour cure' with that drug. If such cells were inherently drug resistant then it should be possible to derive highly resistant tumours by repeated drug treatment. In the first experiment tumours were treated with a single high dose of MeCCNU (35 or 40 mgkg-1) and on regrowth, transplanted into fresh mice and tested for drug sensitivity. Using both excision cell survival and growth delay endpoints, only approximately 25% of tumours were significantly resistant to the test dose, suggesting that many tumours resist the effects of the drug for reasons other than the presence of inherently drug resistant cells. One of the tumours (R4), that regrew after the initial treatment and appeared to be resistant to the test treatment, was retreated with a further 30 mgkg-1 MeCCNU and became more resistant. This line, designated R4/1, was cross-resistant to the other nitrosoureas, BCNU and CCNU, but not to cyclophosphamide, melphalan, cis-platinum or ionising radiation. The effect of treatment dose on the kinetics of MeCCNU resistance development was also studied in a retreatment regimen where the tumours were allowed to regrow and then transplanted into fresh hosts for the next treatment. Resistance developed more quickly at an intermediate dose of 15 mgkg-1 than at 7.5 mgkg-1 where the selective pressure was lower, or at 30 mgkg-1 where there was probably extinction of partially resistant cells. Resistance to MeCCNU developed even more quickly when tumours were retreated several times in the same host, although in a similar experiment with cyclophosphamide no resistance occurred.

Nature and biological significance of DNA modification by the haloethylnitrosoureas.

The haloethylnitrosoureas are both successful antitumour agents and laboratory carcinogens. A growing body of evidence suggests that their biological activities result from DNA modification. By decomposing in different ways, the haloethylnitrosoureas generate intermediates that can introduce either hydroxyethyl or haloethyl groups into DNA. One hydroxyethyl derivative, O6-hydroxyethylguanine, may be responsible for at least some of the carcinogenicity of these compounds. Haloethyl derivatives lead to cross-linked structures which may be cytotoxic. Two such cross-links, 1-(3-deoxycytidyl)-2-(1-deoxyguanosinyl)ethane (dCydCH2CH2dGuo) and 1,2-bis(7-guanyl)ethane (GuaCH2CH2Gua), have been isolated from DNA that has been reacted with haloethylnitrosoureas. Various DNA repair mechanisms, including O6-alkylguanine-DNA alkyltransferase, evidently play a role in modulating both the carcinogenic and cytotoxic actions of these agents.

Update in cancer chemotherapy, Part III: Lung cancer, Part 1.

An update in cancer chemotherapy that deals with the various therapies of lung cancer is described. At present, the stage of the disease and cell type are the major factors that determine the treatment. Important differences in the biological behavior and response to treatment exist between small cell and non-small cell cancers. The small cell type is sensitive to many chemotherapeutic agents. Differences in response to chemotherapy and survival have been less among the non-small cell types.The treatment of non-small cell carcinomas including squamous cell, large cell, and adenocarcinoma are reviewed in Part I of this paper. Small cell lung cancer will be described in Part II, which will be published in a future issue of the journal.