A Multiphysics Thermoelastoviscoplastic Damage Internal State Variable Constitutive Model including Magnetism.

We present a macroscale constitutive model that couples magnetism with thermal, elastic, plastic, and damage effects in an Internal State Variable (ISV) theory. Previous constitutive models did not include an interdependence between the internal magnetic (magnetostriction and magnetic flux) and mechanical fields. Although constitutive models explaining the mechanisms behind mechanical deformations caused by magnetization changes have been presented in the literature, they mainly focus on nanoscale structure-property relations. A fully coupled multiphysics macroscale ISV model presented herein admits lower length scale information from the nanoscale and microscale descriptions of the multiphysics behavior, thus capturing the effects of magnetic field forces with isotropic and anisotropic magnetization terms and moments under thermomechanical deformations. For the first time, this ISV modeling framework internally coheres to the kinematic, thermodynamic, and kinetic relationships of deformation using the evolving ISV histories. For the kinematics, a multiplicative decomposition of deformation gradient is employed including a magnetization term; hence, the Jacobian represents the conservation of mass and conservation of momentum including magnetism. The first and second laws of thermodynamics are used to constrain the appropriate constitutive relations through the Clausius-Duhem inequality. The kinetic framework employs a stress-strain relationship with a flow rule that couples the thermal, mechanical, and magnetic terms. Experimental data from the literature for three different materials (iron, nickel, and cobalt) are used to compare with the model's results showing good correlations.

O6-methylguanine is a critical determinant of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone tumorigenesis in A/J mouse lung.

The relative importance of the two alpha-hydroxylation pathways in the tumorigenicity of the tobacco-specific nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), was examined in the A/J mouse lung. Methyl hydroxylation, which results in DNA pyridyloxobutylation, was investigated with 4-(acetoxymethylnitrosamino)-1-(3-pyridyl)-1-butanone (NNKOAc) and N'-nitrosonornicotine. Methylene hydroxylation, which leads to DNA methylation, was studied by using acetoxymethyl-methylnitrosamine (AMMN). The tumorigenic activities of these compounds were compared to that of 10 mumol NNK at doses that yielded similar or greater adduct levels 24 h after exposure. The methylating agent AMMN was more tumorigenic than the pyridyloxobutylating agents, NNKOAc and N'-nitrosonornicotine. NNKOAc enhanced the tumorigenic activity of AMMN when the two compounds were given in combination. These results suggested that DNA methylation was more important than DNA pyridyloxobutylation in A/J mouse lung tumor induction by NNK and that pyridyloxobutylation enhanced the activity of the methylation pathway. However, the tumorigenicity of 10 mumol NNK could not be reproduced by AMMN +/- NNKOAc at doses that yielded similar levels of DNA adducts 24 h after exposure. Therefore, a second study was conducted in which the persistence of O6-methylguanine in lung DNA following various doses of NNK or AMMN +/- NNKOAc was compared to the tumorigenicity of these treatments. A strong correlation was observed between lung tumor yield and levels of O6-methylguanine at 96 h for NNK and AMMN +/- NNKOAc (r = 0.98). The ability of NNKOAc to increase the tumorigenic activity of AMMN was attributed to its ability to enhance the persistence of O6-methylguanine in lung DNA. These results demonstrate that the formation and persistence of O6-methylguanine are critical events in the initiation of A/J mouse lung tumors by NNK. They also suggest that DNA pyridyloxobutylation by NNK can increase the persistence of this promutagenic base in lung DNA.

Pyridyloxobutyl DNA adducts inhibit the repair of O6-methylguanine.

The carcinogenic tobacco-specific nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), both methylates and pyridyloxobutylates DNA. O6-Methylguanine (O6-mG) persistence has been correlated to NNK-induced lung tumor formation in A/J mice. The pyridyloxobutylation pathway enhances the tumorigenicity of the methylation pathway. In this paper we test the hypothesis that DNA pyridyloxobutylation increases O6-mG persistence by inhibiting the repair protein O6-alkylguanine-DNA alkyltransferase (AGT). Pyridyloxobutylated DNA was generated by reacting calf thymus DNA with the model pyridyloxobutylating agent 4-(acetoxymethylnitrosamino)-1-(3-pyridyl)-1-butanone (NNKOAc) in the presence of esterase. The alkylated DNA inhibited the ability of partially purified rat liver AGT to repair O6-mG when it was incubated with AGT prior to the addition of 3H-methylated DNA. The extent of inhibition was dependent on the amount of NNKOAc reacted with DNA. The ability of NNKOAc-treated DNA to inhibit AGT was destroyed when the DNA was subjected to neutral thermal hydrolysis. Approximately 1 pmol of AGT was inhibited for every 25 to 50 pmol of 4-hydroxy-1-(3-pyridyl)-1-butanone- releasing adducts present in NNKOAc-treated DNA. The inhibitory activity of this alkylated DNA was relatively stable under physiological conditions (pH 7.4, 37 degrees C). Only 13% of the AGT reactive activity was lost after 7 days. When pyridyloxobutylated DNA was incubated simultaneously with 3H-methylated DNA and AGT, a significant reduction in [3H]methyl transfer to AGT was observed. The levels of reduction were similar to those observed when unlabeled methylated DNA containing comparable levels of O6-mG was substituted for NNKOAc-treated DNA. Based on these results, a cocarcinogenic role for pyridyloxobutylation in NNK-induced lung tumorigenesis is proposed in which pyridyloxobutyl DNA adduct(s) compete with O6-mG for reaction with AGT resulting in sustained levels of O6-mG. These enhanced levels then increase the probability of tumor induction by NNK.

Quantitation of microsomal alpha-hydroxylation of the tobacco-specific nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone.

4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is activated to DNA alkylating species via two different alpha-hydroxylation pathways. Methylene hydroxylation leads to DNA methylation, whereas methyl hydroxylation yields DNA pyridyloxobutylation. We have developed a high-pressure liquid chromatography assay utilizing radiochemical detection that permits the determination of the extent of metabolism through each pathway in microsomal preparations. Levels of 4-hydroxy-1-(3-pyridyl)-1-butanone (HPB) were used to measure the extent of methyl hydroxylation, whereas levels of the aldehyde, 4-oxo-1-(3-pyridyl)-1-butanone (OPB), were used to quantify the extent of methylene hydroxylation. Incubations of [5-3H]NNK with microsomes and cofactors were conducted in the presence of 5 mM sodium bisulfite to trap the reactive OPB. The inclusion of bisulfite did not affect the rate of NNK metabolism. Trapping the aldehyde also inhibited its further oxidation to the corresponding acid or reduction to HPB. Furthermore, the conversion of HPB to OPB made only a minor contribution to the OPB levels under our incubation conditions. Analysis of incubation mixtures containing [5-3H]NNK, cofactors, and either A/J mouse liver or lung microsomes demonstrated that OPB was a significant metabolite of NNK. The OPB:HPB ratio was greater in liver (1.5) than in lung (0.2-1) microsomal preparations. Apparent Km values for OPB and HPB formation in lung microsomes were 23.7 and 3.6 microM, respectively, whereas the corresponding values for liver microsomes were 19.1 and 73.8 microM, respectively. These data are consistent with the involvement of more than one cytochrome P-450 isozyme in the activation of NNK to DNA reactive species.

DNA and hemoglobin adducts as markers of metabolic activation of tobacco-specific carcinogens.

Lung cancer is now the leading cause of excess mortality among smokers in the United States. The ability to identify smokers with the greatest risk of developing lung cancer would be an important step in reducing lung cancer mortality. Tobacco-specific nitrosamines such as 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone and N'-nitrosonornicotine are important carcinogens in tobacco smoke. These carcinogens require metabolic activation to exert their carcinogenic effects. Methods are described for the measurement of DNA and hemoglobin adducts formed by the metabolites of these nitrosamines. Preliminary evidence is presented that shows that a subpopulation of smokers have elevated levels of DNA and hemoglobin adducts of tobacco-specific nitrosamines. Further work is in progress to test the hypothesis that smokers with elevated levels of tobacco-specific nitrosamine adducts are at increased risk of developing lung cancer.

Interactions between methylating and pyridyloxobutylating agents in A/J mouse lungs: implications for 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone-induced lung tumorigenesis.

The tobacco-specific nitrosamine, 4-(methylnitrosoamino)-1-(3-pyridyl)-1-butanone, is activated to lung DNA methylating and pyridyloxobutylating intermediates. It is likely that both pathways play a role in lung tumor initiation by this nitrosamine. Previous studies indicated that O(6)-methylguanine (O(6)-mG) persistence is critical for lung tumor formation in A/J mice. The model pyridyloxobutylating agent, 4-(acetoxymethylnitrosamino)-1-(3-pyridyl)-1-butanone (NNKOAc), enhanced the tumorigenic activity of a model methylating agent, acetoxymethylmethylnitrosamine (AMMN), presumably by increasing O(6)-mG persistence in lung DNA. We have been testing the hypothesis that the pyridyloxobutylation pathway increases the mutagenic activity of the DNA methylation pathway by preventing the repair of O(6)-mG by O(6)-alkylguanine-DNA alkyltransferase (AGT). In this study, we report that NNKOAc depletes AGT in lungs but not livers of A/J mice. The consequences of AGT depletion by NNKOAc were then compared with those observed with a known AGT inhibitor, O(6)-benzylguanine (O(6)-bG). NNKOAc and O(6)-bG had similar effects on the levels of AMMN-derived O(6)-mG at 4 and 96 h postinjection. This increase in O(6)-mG levels correlated to increased lung tumor multiplicity in animals simultaneously treated with AMMN (0.75 or 1 micromol) and NNKOAc or O(6)-bG. Only NNKOAc significantly increased lung tumor multiplicity at doses of 0.25 or 0.5 micromol AMMN. The results from these studies indicate that the pyridyloxobutylating agent, NNKOAc, can influence the tumorigenic activity of methylating agents in two ways. At low AMMN doses, the increase in tumor multiplicity is dominated by the additive tumorigenic properties of AMMN and NNKOAc. At higher AMMN doses, NNKOAc appears to enhance the tumorigenic activity of AMMN through enhanced depletion of the repair protein, AGT, leading to increased O(6)-mG persistence. It is likely that similar interactions are important for the organospecific effects of 4-(methylnitrosoamino)-1-(3-pyridyl)-1-butanone.

An improved method for construction of directionally cloned cDNA libraries from microdissected cells.

Here, we developed an improved method for constructing microdissected cDNA libraries, based on strand-switching properties of reverse transcriptase, followed by PCR amplification with primers to mediate unidirectional insert cloning. Using RNA from microdissected ovarian carcinoma cells, we constructed a cDNA library consisting of 1.3 x 10(6) unidirectional recombinants with an average insert size of 500 bp. Single-pass sequencing of 100 clones with the T7 primer revealed 89 inserts derived from known genes, anonymous expressed sequence tags (ESTs), or novel sequences. Among these clones were known genes and ESTs previously found in cDNA libraries from bulk ovarian tissue RNA, sequences seen for the first time in an ovarian-derived library, and novel sequences not previously seen in any cDNA library. These results demonstrate a methodology for constructing quality cDNA libraries that are cloned in a unidirectional fashion, are complex and diverse, and reflect the tissue of origin.

Treatment of renal artery aneurysms.

Renal artery aneurysms (RAAs) represent a rare disease and are most commonly discovered as an incidental imaging finding. RAA may be associated with hypertension and are usually asymptomatic at presentation but may result in rupture, hematuria, or renal infarction. The natural history of RAA is poorly understood. Although there is general consensus that RAA that are symptomatic or identified in women at risk for pregnancy should be repaired, diameter criteria for repair of asymptomatic RAA are controversial and emerging evidence suggests that rupture incidence is low for those <2.5 cm in diameter. Options for repair of RAA have expanded over the preceding decades with expansion of both open surgical and endovascular treatments.

Proxy measures of vitamin D status - season and latitude - correlate with adverse outcomes after bariatric surgery in the Nationwide Inpatient Sample, 2001-2010: a retrospective cohort study.

OBJECTIVE: To investigate the association between adverse surgical outcomes following bariatric surgery and proxy measures of vitamin D (VitD) status (season and latitude) in the Nationwide Inpatient Sample (NIS). BACKGROUND: Obesity is an independent risk factor for VitD deficiency (25(OH)D < 20 ng ml-1). VitD deficiency compounds the chronic inflammation of obesity, increasing the risk of adverse outcomes following bariatric surgery. Epidemiology has long used season and latitude as proxies for group VitD, as VitD status is largely determined by sun exposure, which is greatest during summer and at the Equator. METHODS: We assessed proxy measures of group VitD status. We compared surgeries in VitD Summer (July to September), Winter (January to March), and Fall/Spring (October to December and April to June) and in the North (≥37°N) vs. the South (<37°N). RESULTS: We identified 932,091 bariatric surgeries; 81.2% were women and 74.4% were white. Sex was unequally distributed by season (p = 0.005). Median age was 43.0 years (all groups). Most surgeries occurred in the North (64.8%). Adverse outcome rates ranged from 0.01% (wound infections) to 39.4% [prolonged length of stay {LOS}]. Season was inversely associated with wound infection (p = 0.018) and dehiscence (p = 0.001). Extended LOS was inversely correlated with season (p < 0.001). These relationships held after adjustment. Prolonged LOS (p < 0.001) and any complication (p = 0.108) were more common in the North. CONCLUSIONS: We have demonstrated a graded relationship between seasonality and adverse outcomes following bariatric surgery. The association was strongest for dehiscence and prolonged LOS. These relationships held when using latitude. A prospective study measuring pre-operative 25(OH)D concentration would strengthen the case for causality in adverse surgical outcomes.

Regio- and stereochemical studies on the alpha-carbon oxidation of (S)-nicotine by cytochrome P-450 model systems.

Results from previous studies indicate that rabbit liver microsomal cytochrome P-450 catalyzes the C-5' two-electron oxidation of (S)-nicotine stereoselectivity with preferential loss of the pro-(E)-hydrogen atom trans to the pyridine ring. We now have examined the regio- and stereochemical features of the oxidation of (S)-nicotine by peroxides in the presence of various hemoproteins and by electrochemical and photochemical methods. None of these systems gave rise to the stereochemical outcomes observed with the cytochrome P-450 mediated reaction. The results of these studies are interpreted as additional evidence for the formation of a highly ordered complex between (S)-nicotine and cytochrome P-450 that directs the regio- and diasterioselective alpha-carbon oxidation of this substrate.

Stereochemical studies on the cytochrome P-450 catalyzed oxidation of (S)-nicotine to the (S)-nicotine delta 1'(5')-iminium species.

Mammals metabolize the tobacco alkaloid (S)-nicotine primarily to the lactam (S)-cotinine by a pathway involving an initial cytochrome P-450 catalyzed two-electron oxidation at the prochiral 5'-carbon atom. The stereochemical course of this oxidation was examined with human microsomal preparations and the E and Z diastereomers of (S)-nicotine-5'd1. The metabolically generated delta 1'(5')-iminium ion intermediate was trapped and analyzed as the corresponding diastereomeric 5'-cyano derivatives by a capillary column GC-EIMS selected ion monitoring assay. The results of these studies established that this biotransformation proceeds with the stereoselective abstraction of the 5'-pro-E proton, that is, the C-5' proton trans to the bulky pyridyl group. The observed stereoselectivity was independent of proton vs. deuteron abstraction. Additionally, the extent of (S)-cotinine formation was minor and did not influence the stereochemical composition of the metabolically derived alpha-cyano amines. Studies with male Dutch rabbit liver microsomal preparations gave similar results. These findings suggest that the structure of the complex formed between (S)-nicotine and the active site of cytochrome P-450 is highly ordered and dictates the stereochemical course of the reaction pathway.

Studies on the 1-methyl-4-phenyl-2,3-dihydropyridinium species 2,3-MPDP+, the monoamine oxidase catalyzed oxidation product of the nigrostriatal toxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP).

The nigrostriatal toxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is biotransformed by brain monoamine oxidase (MAO) to an unstable dihydropyridinium intermediate that reacts with cyanide ion to form an alpha-cyano-tetrahydropyridine adduct and, in the absence of cyanide ion, undergoes disproportionation to the 1-methyl-4-phenylpyridinium species MPP+ and MPTP. Comparison of the HPLC retention times, diode array UV, and chemical ion mass spectral characteristics of these products with those of synthetic standards led us to propose the 1-methyl-4-phenyl-2,3-dihydropyridinium species 2,3-MPDP+ and 6-cyano-1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine as tentative structure assignments for the dihydropyridinium metabolite and the cyano adduct, respectively. Results presented in this paper confirm the first assignment and establish that, although the proposed 6-cyano adduct is initially formed, the product that was isolated from the mitochondrial incubation mixtures of MPTP and sodium cyanide actually is the isomeric 2-cyano-1-methyl-4-phenyl-1,2,3,6 -tetrahydropyridine. On the basis of the selective incorporation of deuterium into these products, we provide rational mechanistic interpretations of the disproportionation reaction and the rearrangement of the cyano adducts. These results establish that the MAO-catalyzed bioactivation of MPTP leads to the formation of a variety of reactive molecules that are potentially cytotoxic to nigrostriatal cells.

Metabolism of the nigrostriatal toxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine by liver homogenate fractions.

The metabolic fate of the nigrostriatal toxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) has been examined in rat and rabbit liver mitochondrial and rabbit liver microsomal preparations. The mitochondrial preparations rapidly oxidized MPTP, in a pargyline-sensitive reaction, to a polar material that was shown to contain the 1-methyl-4-phenylpyridinium species as the principal product. NADPH-supplemented microsomal preparations converted MPTP to two principal products: 4-phenyl-1,2,3,6-tetrahydropyridine and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine N-oxide. Carbon monoxide and SKF 525A selectively inhibited the oxidation of MPTP to the nor compound, indicating that this N-demethylation reaction is cytochrome P-450 catalyzed. Attempts to trap possible unstable iminium metabolites of MPTP in microsomal incubation mixtures with sodium cyanide led to the isolation of a monocyano adduct that proved to be the N-cyanomethyl derivative. Thus, hepatic mitochondrial and microsomal enzyme systems catalyze the oxidation of MPTP by different pathways, the former leading to the generation of species that may possess neurotoxic properties.

Mechanism of enhancement of esophageal tumorigenesis by 6-phenylhexyl isothiocyanate.

6-Phenylhexyl isothiocyanate (PHITC) enhances esophageal tumorigenesis induced by the carcinogen N-nitrosomethylbenzylamine (NMBA) in rats while its shorter chain analog, phenethyl isothiocyanate (PEITC), inhibits NMBA-induced esophageal tumorigenesis. A significant increase in O6-methylguanine levels in esophageal DNA at 72 h after NMBA administration to rats pretreated with PHITC suggested that PHITC might enhance NMBA metabolic activation or inhibit DNA repair. To test this hypothesis, groups of 20 rats were administered PEITC or PHITC at concentrations of 0, 1.0, or 2.5 mmol/kg in modified AIN-76A diet for 2 weeks. The esophagi were removed from rats, stripped, split, and maintained in HEPES buffered saline (HBS) for assays of NMBA metabolism (n = 5 per group) or were snap frozen for DNA repair assays (n = 15 per group). The principal metabolites of NMBA produced by esophageal explants were: two unidentified peaks, benzyl alcohol (at 4 h only), and benzoic acid. Esophageal explants from PEITC-treated animals showed a significantly decreased ability to metabolize NMBA as expected. PHITC-treated animals showed a slight inhibition in the formation of most NMBA-related metabolites, rather than an overall increase in NMBA activation. This inhibition was less than that observed with PEITC. No inhibitory effects were observed on O6-alkylguanine transferase (AGT) activity in the esophagi of rats treated with 1.0 micromol/g or 2.5 micromol/g PHITC. Thus, effects of PHITC on esophageal metabolism and DNA repair do not account for the enhancement of NMBA tumorigenicity by PHITC.

Tobacco-specific nitrosamine adducts: studies in laboratory animals and humans.

This paper describes quantitation of human hemoglobin and DNA adducts of the carcinogenic tobacco-specific nitrosamines 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N'-nitrosonornicotine (NNN). NNK and NNN are believed to be involved in cancers of the lung, esophagus, oral cavity, and pancreas in people who use tobacco products. The adduct dosimetry method employs GC-MS for quantitation of 4-hydroxy-1-(3-pyridyl)-1-butanone (HPB) released by mild base hydrolysis of hemoglobin or acid hydrolysis of DNA as a biochemical marker of the pyridyloxobutylation metabolic activation pathway. Approximately 22% of smokers (n = 101) had elevated levels of HPB released from hemoglobin (range, 200-1600 fmole/g Hb). Adduct levels in snuff dippers ranged from 200-1800 fmole/g Hb. HPB levels in nonsmokers were generally below the detection limit. Acid hydrolysis of lung and tracheal DNA obtained at autopsy and analysis for released HPB revealed levels ranging up to 50 fmole/mg DNA in smokers; the adduct was not detected in nonsmokers. These findings are consistent with data generated in studies of adduct formation by NNK in rats. The biological significance of the HPB-releasing DNA pyridyloxobutylation pathway was compared to that of the DNA methylation pathway in the A/J mouse. These studies demonstrated that the persistence of O6-methylguanine in lung DNA is critical for tumorigenesis by NNK and that pyridyloxobutylation enhances both persistence of O6-methylguanine and tumorigenesis by acetoxymethylmethylnitrosamine. In the rat, the relative roles of methylation and pyridyloxobutylation in lung tumorigenesis by NNK are not as clearly defined.(ABSTRACT TRUNCATED AT 250 WORDS)

Activation of dihaloalkanes by glutathione conjugation and formation of DNA adducts.

Ethylene dibromide (1,2-dibromoethane, EDB) can be activated to electrophilic species by either oxidative metabolism or conjugation with glutathione. Although conjugation is generally a route of detoxication, in this case it leads to genetic damage. The major DNA adduct has been identified as S-[2-(N7-guanyl)ethyl]glutathione, which is believed to arise via half-mustard and episulfonium ion intermediates. The adduct has a half-life of about 70 to 100 hr and does not appear to migrate to other DNA sites. Glutathione-dependent DNA damage by EDB was also demonstrated in human hepatocyte preparations. The possible relevance of this DNA adduct to genetic damage is discussed.

The antagonism of nicotine-induced cardiovascular responses by DMAE and DEO analogs.

A series of quaternary ammonium compounds cinsisting of 4, 4'-bis-[N-(2, 2-diethoxyethyl)-N, N-dimethylammonioacetyl]-biphenyl dibromide (DMAE) and 4, 4'-bis-[N, N-di(2-ethoxyethyl)-N-methylammonioacetyl]-biphenyl dibromide (DEO) analogs was investigated for selective nicotine antagonism. Each series of compounds contained the monophenyl (MPh.DMAE, MPh.DEO); biphenyl (DMAE, DEO); terphenyl (TPh,DMAE, TPh.DEO); half-molecule (1/2DMAE, 1/2DEO); p-phenyl half-molecule (p-Ph.-1/2DMAE, p-Ph.-1/2DEO) and biphenyl half-molecule (p-BPh.-1/2DMAE, p-BPh.-1/2DEO) analogs. Studies were conducted on isolated spontaneously beating guinea pig atria and anesthetized dogs. Relative potencies of the DMAE and DEO series to antagonize the nicotine (20 mug/ml) induced positive chronotropic effect of the guinea pig atria were determined as follows: DMAE (1.0); TPh.DMAE (0.82); P-Ph.1/2DMAE (0.59); DEO (0.54); MPh.DMAE (0.27); TPh.DEO (0.26); MPh.DEO (0.18); p-Ph.-1/2DEO (0.16); 1/2DMAE (0.03); 1/2DEO (0.02); p-BPh.-1/2DMAE (less than 0.01); p-BPh.-1/2DEO (less than 0.01) and C-6 (0.85). The I50 to antagonize nicotine induced responses by DMAE was 0.13 muM (0.10 mu/ml). Several of the above analogs were studied in the dog and their ability to antagonize nicotine (100 mug/kg) induced positive chronotropic effects were compared with their ability to inhibit transmission through the stellate or the superior cervical ganglia. The I50 doses of the drugs antagonizing nicotine, impairing superior cervical ganglionic transmission and the corresponding fold shifts in the dose--response curves follow: DMAE (120 mug/kg, 3.0 mg/kg, 25); TPh.DMAE (40 mug/kg, 1.10 mg/kg, 30), DEO (45 mug/kg, 1.30 mg/kg, 25) and C-6 (140 mug/kg, 0.42 mg/kg, 0.42 mg/kg, 3.0). These findings are suggestive of the hypothesis that receptors normally activated by endogenously released ACh in the stellate or superior cervical ganglia of the dog may be dissociated from those receptors activated by nicotine which results in an increase in blood pressure or heart rate. Clinical implications are that TPh.DMAE as well as other DMAE analogs may pose less of a problem with hypotension than hexamethonium as a nicotine antagonist.

Secondary acute myelogenous leukemia with MLL gene rearrangement following radioimmunotherapy (RAIT) for non-Hodgkin's lymphoma.

Targeted therapy with conjugated and unconjugated monoclonal antibodies for non-Hodgkin's lymphoma has revolutionized the approach to this disease. The efficacy and low toxicity of these agents have allowed introduction of this strategy in the early stages of therapy. Longer follow-up is needed before validating the safety of these agents. Since monoclonal antibodies are being given as front-line therapy, it is important to identify all potential adverse events. We report a case of secondary acute myelogenous leukemia (AML) with 11q23 cytogenetic abnormality and mixed lymphoid leukemia (MLL) gene expression in a patient treated with Y90 labeled anti-CD20 antibody (Zevalin). The patient was not exposed to topoisomerase II inhibitors. Our observations suggest a relationship between 11q23 leukemia and radioimmunotherapy (RAIT) and further studies are needed.

Enteroclysis in partial small bowel obstruction.

In a 5 year period, 56 patients with suspected partial small bowel obstruction were evaluated by enteroclysis or the antegrade small bowel enema. Mechanical partial obstruction was diagnosed by enteroclysis in 38 of the patients, 24 of whom required surgery. The diagnosis by enteroclysis was confirmed in 23 of the patients. In the single patient with "false-positive" enteroclysis, the obstruction had been interpreted as minimal. The thirteen remaining patients were managed conservatively. The possibility of significant mechanical obstruction was excluded by enteroclysis in 19 patients. There were no complications associated with the procedure. Enteroclysis is a safe, rapid, and accurate method for the evaluation of patients with partial small bowel obstruction.

Analysis of mutagenic activity and ability to induce replication of polyoma DNA sequences by different model metabolites of the carcinogenic tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone.

The tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) requires metabolic activation to express its carcinogenic activity. This activation leads to the formation of methylating and pyridyloxobutylating agents. To determine the possible biological effects mediated by each of these metabolic pathways we have studied the activities of model compounds that are metabolized to either a methylating or pyridyloxobutylating species. Each model compound was evaluated for its mutagenic activity in both prokaryotic and eukaryotic cell systems. The model compounds were also tested for their ability to induce asynchronous replication of viral DNA sequences. We demonstrate here that both the methylating model compound acetoxymethylmethylnitrosamine (AMMN) and the pyridyloxobutylating model compound 4-(acetoxymethyl)-1-(3-pyridyl)-1-butanone (NNKOAc) were mutagenic in strains TA98, TA100, and TA1535 but not TA102. While NNKOAc appeared to be 10 times more potent than AMMN in Salmonella, AMMN was found to be a more potent mutagen in mammalian G12 cells. Both chemicals could induce asynchronous replication of polyoma DNA sequences in rat fibroblast cells carrying an integrated copy of the polyoma virus with AMMN appearing to be more active. Measurement of DNA adduct levels suggest that the damage produced by NNKOAc was at least as active as that produced by AMMN when viewed on a per adduct basis. The possible implications of the biological activities exhibited by methylating and pyridyloxobutylating model compounds to NNK induced carcinogenesis are discussed.