Left ventricular systolic performance during upright bicycle exercise in patients with essential hypertension.

Left ventricular performance was evaluated at rest and during maximal upright bicycle exercise in 51 patients with chronic essential hypertension. Twenty-eight of these patients had no clinical or electrocardiographic evidence of coronary artery disease and comprise the primary study population. The remaining 23 patients had coronary artery disease and represent a comparison group. First-pass radionuclide angiocardiograms were obtained at rest and during maximal upright bicycle exercise, allowing evaluation of global left ventricular ejection fraction and regional wall motion. At the time of the radionuclide studies, all patients were hypertensive, defined as a diastolic blood pressure 90 mm Hg or greater and/or a systolic blood pressure 140 mm Hg or greater with the patient at rest and sitting. In the primary study group, the left ventricular functional response to upright bicycle exercise was normal in 26 of 28 patients. Left ventricular ejection fraction averaged (+/- standard error) 65 +/- 2 percent at rest and increased significantly to 76 +/- 2 percent with exercise (p less than 0.001). Regional wall motion was normal both at rest and during exercise in all patients. Seventeen patients had electrocardiographic evidence of left ventricular hypertrophy, and 14 were receiving propranolol therapy. The left ventricular functional response also was normal in these subgroups. In contrast to the nearly uniform normal left ventricular responses noted in the patients with hypertension alone, the group with concomitant coronary artery disease had a markedly higher incidence of abnormal left ventricular reserve (19 of 23 versus two of 28, p less than 0.001) during exercise. Thus, in most patients with essential hypertension but without concomitant coronary artery disease, left ventricular reserve during exercise was normal. Hypertension, even with left ventricular hypertrophy, should not be viewed as the cause for an abnormal left ventricular response to exercise in a patient undergoing diagnostic exercise radionuclide angiocardiography.

Regional myocardial kinetics of lidocaine in experimental infarction: modulation by regional blood flow.

The regional myocardial concentration of lidocaine after intravenous bolus administration was studied in the setting of myocardial infarction in 27 dogs utilizing a 24 hour old infarct model. Myocardial levels of lidocaine measured by gas chromatography were related to regional myocardial blood flow measured by radioactive microspheres in the same sample. A highly significant positive linear relation was noted between relative regional myocardial blood flow and lidocaine tissue concentration in animals killed 1 and 3 minutes after the injection of lidocaine (R2 = 0.81 and 0.85, respectively). This positive linear relation was no longer evident at 5 or more minutes after injection of lidocaine. This lack of linear relation resulted from dramatic reductions in myocardial lidocaine concentration in normally perfused zones with much lesser reductions in lower flow zones. Thus the initial distribution of lidocaine after bolus injection is directly proportional to myocardial blood flow within the first 3 minutes of injection. Thereafter, the washout of lidocaine appears to be the dominant factor in myocardial distribution.

Regional myocardial lidocaine concentration following continuous intravenous infusion early and later after myocardial infarction.

The regional concentration of lidocaine using a double constant infusion technique (250 micrograms/kg/min x 15 minutes followed by 35 micrograms/kg/mg/min x 120 minutes) was studied immediately (2 hours) in seven dogs and 24 hours (six dogs) after myocardial infarction. Tissue levels were determined by gas chromatography and related to regional myocardial blood flow as determined by the radioactive microsphere technique in multiple samples. At 2 hours after infarction a significantly higher lidocaine concentration (4.1 +/- 0.42 micrograms/g) was found in zones with greatly reduced blood flow (regional myocardial blood flow less than 0.2 ml/min per g) when compared with that (2.6 +/- 0.19 micrograms/g) in zones with normal blood flow (regional myocardial blood flow greater than 0.8 ml/min per g) (p less than 0.01). In contrast, in the 24 hour model the opposite situation was observed. Although the concentration of lidocaine in the infarct zone was substantial, a significant decline in lidocaine tissue concentration was found in the zones of lowest blood flow (regional myocardial blood flow less than 0.2 ml/min per g) when compared with that in normal zones (1.76 +/- 0.21 versus 3.38 +/- 0.21 micrograms/g, p less than 0.001). In addition, no significant differences in lidocaine concentrations were found between endocardium and epicardium in any of the groups other than those related to regional myocardial blood flow. Thus, with the double constant infusion technique, lidocaine reached normal and ischemic myocardium in concentrations equivalent to therapeutic plasma concentrations, even in lower infarct blood flow zones, with no significant differences between endocardium and epicardium. Of perhaps greater significance, the age of the ischemic insult is an important determinant of lidocaine tissue distribution in infarcted myocardium.

Prediction of rodent carcinogenicity of further 30 chemicals bioassayed by the U.S. National Toxicology Program.

Recently the U.S. National Toxicology Program (NTP) sponsored a comparative exercise in which different prediction approaches (both biologically and chemically based) were challenged for their predictive abilities of rodent carcinogenicity of a common set of chemicals. The exercise enjoyed remarkable scientific success and stimulated NTP to sponsor a second challenging round of tests, inviting participants to present predictions relative to the rodent carcinogenicity of a further 30 chemicals; these are currently being tested. In this article, we present our predictions based on structure-activity relationship considerations. In our procedure, first each chemical was assigned to an activity mechanism class and then, with semiquantitative considerations, was assigned a probability carcinogenicity score, taking into account simultaneously the hypothesized action mechanism and physical chemical parameters.

Modulation of DNA binding in vivo by specific humoral immunological response: a novel host factor in environmental carcinogenesis?

To investigate the possible modulatory effect of the immune response induced by recurrent carcinogen exposure, a specific humoral immune response toward 2-acetylaminofluorene (2-AAF) was elicited in Swiss mice with repeated intraperitoneal injections of a 2-AAF-gelatin conjugate. The immunization procedure resulted in the production of specific anti-2-AAF antibodies in all treated animals. Groups of immunized and nonimmunized mice were subsequently fed 2-AAF pelleted in the diet at 50 and 150 ppm for 4 weeks. At the end of 2-AAF administration, animals were sacrificed and the content of 2-AAF-adducts in liver DNA was determined by enzyme-linked immunoadsorbent assay using a polyclonal rabbit antiserum. The comparison of the adducts levels in immunized and nonimmunized mice (receiving either the vehicle or the adjuvant alone during pretreatment) demonstrates a highly significant (p < 0.001) difference among groups, with far lower adduct levels in immunized animals. No significant difference in food consumption or liver metabolic activities was observed among experimental groups, suggesting the absence of external bias. The mechanism underlying the result observed is not yet clear; however, the experimental data strongly suggest that the specific immunological response induced by recurrent carcinogen exposure may exert a modulatory effect and act as a relevant host factor in chemical carcinogenesis.

Lidocaine kinetics: relationships between early lidocaine kinetics and indocyanine green clearance.

Lidocaine plasma levels and indocyanine green clearance were measured in five normal volunteers and eight patients admitted to the coronary care unit. All individuals received lidocaine as a 1 mg/kg bolus and a 35 microgram/kg/min constant infusion for 180 minutes. Eight of the 13 (62 per cent) individuals studied (all normal volunteers and three patients) developed early, potentially subtherapeutic plasma lidocaine levels (less than or equal to 2.4 microgram/ml) within 15 minutes after starting therapy. Those individuals with subtherapeutic levels had either minimal (American Heart Association Class) or no clinical evidence of congestive heart failure. The use of indocyanine green (ICG) clearance as an estimate of hepatic plasma flow showed that individuals with early, subtherapeutic lidocaine levels had higher ICG clearance (9.33 +/- 0.32 ml/min . kg versus 2.90 +/- 1.74 ml/min . kg) and shorter ICG t 1/2 (2.02 +/- 0.99 minutes versus 3.6 +/- 0.69 minutes) and larger volume of distribution (36.1 +/- 16.3 ml/kg versus 19.5 +/- 12.8 ml/kg) than patients without subtherapeutic levels. This study suggests that early lidocaine kinetics may be significantly altered by clinical conditions that alter hepatic blood flow. The reappearance of arrhythmias shortly after initiating lidocaine therapy in patients without heart failure may be due to rapid hepatic clearance and subtherapeutic blood levels rather than lidocaine-resistant arrhythmias.

Intraoperative use of nifedipine for hemodynamic collapse due to coronary artery spasm following myocardial revascularization.

Sudden hemodynamic collapse in the perioperative period following myocardial revascularization may be due to coronary artery spasm. Nitroglycerin has been the standard treatment for this; however, it is not always effective, and the resultant morbidity and mortality are high. We present the case of a patient in whom sudden hemodynamic collapse due to coronary artery spasm was refractory to intravenously administered nitroglycerin but was relieved quickly with sublingually administered nifedipine. In certain selected patients in whom coronary artery spasm is responsible for myocardial collapse, the drug nifedipine may be effective in relieving this spasm and allowing for myocardial recovery.

Determination of serum levels of 2,6 diethylaniline in laboratory animal treated with Alachlor.

In order to estimate the environmental risk of the use of Alachlor, experiments on laboratory animals were conducted. Alachlor and 2,6 diethylaniline content in blood serum was quantified. Three groups of male ACI/T rats and C3H/FEJ mice were treated with three different doses of Alachlor. Six hours after the intraperitoneal injection the animals were bled and blood was collected by cardiac puncture. From serum obtained after blood centrifugation, A and DEA were extracted using diethyl ether. 2,6 diethylaniline and Alachlor determinations were carried out by high performance liquid chromatography (HPLC). The HPLC revealed that the metabolic capacity of 2,6 diethylaniline production from Alachlor in rats is dose-dependent; moreover, the animals can be subdivided into at least two groups, according to their Alachlor metabolic capacities. In mice the metabolic release of 2,6 diethylaniline was found to be practically complete at every dose tested.

Identification of optimal conditions for the detection of benzo[a]pyrene-DNA adducts by enzyme-linked immunoadsorbent assays (ELISA).

The aim of the present report was to establish the optimal conditions for the detection of polycyclic aromatic hydrocarbon adducted to DNA by enzyme-linked immunoadsorbent assays (ELISA). Racemic 7,t-8-dihydroxy-t-9,10-epoxy-7,8,9,10-tetrahydro-benzo[a]pyrene ((+/-)-anti-BPDE) modified DNA samples were produced in vitro, by reacting (+/-)-anti-BPDE with calf thymus DNA, and in vivo in Swiss female mice by single i.p. injection of benzo[a]pyrene (B[a]P) (200 mg/kg body weight dissolved in tricaprylin). The BPDE adduct content in vitro and in liver and lung modified DNA was detected by direct and competitive ELISA using serial dilutions of the samples in unmodified calf thymus DNA, and polyclonal rabbit immunoglobulin-G elicited toward BPDE-DNA and BPDE-gelatin, both produced in our laboratory. The carcinogen-macromolecule conjugate in which adducts were sought could be used as an immunogen to produce a specific and potent antibody. Moreover, the modification level of the ELISA standards should be as close to the range as of the biological samples to correctly calculate the adducts, since different binding efficiency between antibody and BPDE-modified DNA is dependent on the BPDE modification level (33). Appropriate extraction of the in vitro modified samples is also necessary to guarantee the exact covalent modification level, eliminating noncovalently linked BPDE. Under these conditions, our results confirm that competitive ELISA is much more sensitive than the direct method, mainly because of the limitations caused by the coating of the antigen in each well (max 5 micrograms DNA/well), whereas the amount of DNA (modified or not) that can be employed for adduct detection by competitive ELISA increases 20-fold. The sensitivity obtained was 0.5 fmol B[a]P/microgramDNA (1.6 adducts/10(7) nucleotides).

Synovial sarcoma: an Australian series of 48 cases.

A series of 48 cases of synovial sarcomas submitted to the Australasian Soft Tissue Tumour Registry between 1965 and 1980 is reported. Tumours were analysed with regard to clinical features, morphology and outcome. The overall 5-yr survival rate for all assessable cases was 50%. A strong relationship between size and survival was noted with a 73% 5-yr survival rate where tumours were less than 5 cm in maximum diameter. Biphasic tumours (16 cases) appeared to have a better prognosis, with a mean survival time of 6.1 yr as compared with 4 yr for monophasic tumours (32 cases); however, the former were generally slightly smaller tumours. Tumours with less than 5 mitoses per 10 highpower fields (2.8 sq mm) had double the mean survival time of other tumours. The histological features of swirling architecture, monotonous cell type, vascular pattern, myxoid foci, collagen production, mast cell presence and calcification are recommended as cumulative factors in arriving at a diagnosis where a biphasic pattern is not apparent.

Mutagenicity of commercial hair dyes in Salmonella typhimurium TA98.

Commercial permanent hair-dye formulations containing p-phenylenediamine, resorcinol and aminophenols were incubated with hydrogen peroxide and then tested for their ability to induce reverse mutations in Salmonella typhimurium TA98. Approximately half of the formulations (12 out of 25) gave positive results. The activity varied widely in degree and was observed only in the presence of an S-9 microsomal fraction from Aroclor-induced male rats. Five of the 12 positive formulations and one negative dye were administered topically to male rats; with one exception the urines of animals treated with the mutagenic hair dyes gave positive results in the presence of the S-9 mix.

Monitoring of urinary mutagenicity in workers exposed to low doses of 2,4,7-trinitro-9-fluorenone.

A monitoring of the urinary mutagenicity in workers occupationally exposed to low doses of 2,4,7-trinitro-9-fluorenone (TNF) was undertaken. Urine concentrate of 22 exposed workers (11 smokers and 11 nonsmokers) and 18 presumedly unexposed workers (7 smokers and 11 nonsmokers) were assayed for mutagenicity in Salmonella typhimurium strain TA98 with the plate incorporation technique. In this test system none of the urine concentrate was effective as a mutagen, either in the absence or presence of S9. Fifteen urine samples (8 from exposed workers, 7 from referents) were also tested in the microtiter fluctuation assay. With this technique smoking habits were significantly related to urinary mutagenicity in tests performed with metabolic activation. In neither case however was the association between presumed exposure and urinary mutagenicity significant. These results were evaluated on the basis of urinary mutagenicity data obtained from rats exposed to TNF by different routes. It was shown that the observed urinary mutagenicity accounts for a minor fraction of the administered TNF dose (about 0.1 to 0.2%, depending on the route of exposure); thus it is possible that low-level exposure to TNF could escape detection by urinary mutagenicity monitoring.

Low doses and thresholds in genotoxicity: from theories to experiments.

The absence of threshold in the action of genotoxic carcinogens was theoretically postulated more than thirty years ago, but continuously challenged for scientific and practical reasons. The direct experimental demonstration of the presence of a threshold for genotoxic damage is precluded by the insufficient sensitivity of the biological methods presently available. In the last twenty years the sensitivity of the methods for quantitative determination of the DNA adducts of the carcinogens was enormously improved, demonstrating linearity of the dose/adducts pattern over dose intervals of more than million-fold. The arguments more often advanced for the presence of a threshold for genotoxic carcinogens were mainly based on the action of intracellular scavengers, detoxification enzymes and repair systems, being able to block completely the genotoxic carcinogens at very low doses. This hypothesis is disproved by the constant presence of DNA adducts at extremely low doses of different carcinogens, whatever their chemical structure can be. On the other hand if genotoxic damage results from damage to proteins involved in cell division, like tubulin, there is a threshold dose for such genotoxic effects. The detailed knowledge of the genotoxicity mechanism is therefore needed for a sound carcinogenic risk assessment. Most of the genotoxic carcinogens, or their metabolites, damage directly the DNA. In this case the absence of threshold must be assumed, not only for theoretical reasons, but for the results of the experiments quantitatively relating DNA damage and very low doses of carcinogens. For the sake of clarity the "adjectivated" thresholds, like practical pragmatic, apparent and operational, must disappear from documents analysing the carcinogenic risk.

Divergent synergic effects in carcinogenesis initiation by simultaneous exposure to two genotoxic carcinogens.

Carcinogenesis is a complex and multistep process starting from initiation to tumor progression. Synergistic mechanisms can occur at every step of the process. The aim of this work was to provide information about the effect of chemical carcinogens which, if administered in combination, result in positive as well as negative synergistic effects. In order to evaluate whether for some carcinogens synergism occurs at the initiation step, we compared the effects of Ethylmethanesulfonate (EMS) on Benzo[a]pyrene (BP)-DNA adducts formation in the liver and lung of male Swiss mice treated for seven days by i.p. dose of EMS (1.2 mg/Kg b.w.) alone or by simultaneous administration of three doses of BP (25, 50, 100 mg/Kg b.w.) injected i.p. or the first day of treatment. A group of Swiss mice was treated by BP alone. At it was demonstrated in our laboratory that previous immunization toward BP influences the adduct levels of this carcinogen (14), the same treatments (BaP alone and BaP with EMS) were carried out in mice previously immunized toward BP. Liver and lung 1 BP-DNA adducts were detected in all the groups treated by both BP and EMS as compared to the group treated with BP alone. The EMS-BP association in non-immunized mice showed an antagonistic effect in the liver and a synergistic effect in the lung. In immunized mice a synergistic effect was obtained in both liver and lung. Moreover, the efficiency of both the synergistic and antagonistic effect, depended on BP dose of treatment. It is reasonable to draw the conclusion that simultaneous exposure to BP and EMS leads to different organ-specific and dose-dependent effects. This first preliminary result showed that the pattern of the interaction between genotoxic carcinogens is more complex that was foreseen, even at the stage of DNA adducts formation.

Production and characterization of monoclonal antibodies against DNA single ring diamines adducts.

The synthetic conjugate of the genotoxic compound 2,4 diaminotoluene (2,4 DAT) with gelatin (2,4 DAT-GEL) was employed to elicit specific antibodies directed against a restricted class of aromatic diamines. Using this immunogen, mouse monoclonal antibodies (MAbs) have been produced. These MAbs have been characterized and used in ELISA to detect 2,4 DAT covalently linked to biopolymers. The MAbs could bind to different synthetic 2,4 DAT-biopolymer adducts as well as to DNA from rats treated in vivo with the aromatic diamine, but they did not react with gelatin or biopolymers alone. The use of these MAbs has been investigated in order to develop a highly sensitive test to detect adducts of this genotoxic compound with nuclear DNA.

Specificity of rabbit antibodies elicited by related synthetic peptides.

Three 17-residue peptides, presenting from 65% to 70% sequence homology, and one endecapeptide, with no apparent homology with the first three, were chemically synthesized and investigated in their ability to elicit rabbit antipeptide antibodies. The complex cross reactivities of the antisera were investigated by testing the binding of the antibodies to the intact peptides, to their enzymatic fragments, and by the use of specific immunoadsorbents. Antipeptide antibodies may or may not crossreact with related "parent" peptides, this depending upon number, distribution, and localization of amino acid differences in low or high antigenicity regions of the immunogen. Related peptides may elicit antibodies that crossreact almost completely, and therefore not specific for one or the other "parent" peptide. Those antibodies may therefore be of little use for the selective recognition of closely related structures.