Saphenous vein graft aneurysm fistula formation causing right heart failure: an unusual presentation.

Saphenous vein graft aneurysm (SVG) formation after coronary artery bypass grafting is a rare complication of the surgery. We present a case of a 68-year-old man with an unusual presentation of such an aneurysm. Thirty-four years after his initial bypass surgery, the patient presented with a fistula formation into his right atrium from a vein graft aneurysm. Late aneurysm formation is thought to occur secondary to atherosclerotic degeneration of the SVG with background hypertension and dyslipidaemia accelerating the process. Diagnostic modalities used to investigate SVG aneurysms include computed tomography, transthoracic echocardiogram, magnetic resonance imaging and cardiac catheterisation. Aneurysms with fistula formation historically require aggressive surgical intervention. Resection of the aneurysm with subsequent revascularisation if required is the surgical norm. SVG aneurysm with fistula formation into a cardiac chamber is a rare complication of coronary artery bypass grafting (CABG), which can occur with atypical presenting symptoms. Physicians should keep in mind the possibility of this occurring in post-CABG patients presenting with heart failure and a new murmur.

Left ventricular response to exercise and autonomic control mechanisms in end-stage renal disease.

Left ventricular (LV) function during rest and during exercise was evaluated in patients with end-stage renal disease (ESRD) in whom other causes of LV dysfunction were eliminated through rigid selection criteria. Autonomic function was also assessed in these patients with Valsalva's maneuver and plasma catecholamine determinations. Echocardiography and radionuclide ventriculography in the group with ESRD revealed no abnormalities of LV wall motion or ejection fraction. During graded exercise, patients with ESRD achieved 85% of age-predicted heart rate, and no differences in exercise tolerance or LV function were observed. Valsalva's response was abnormal in patients with ESRD, and post exercise the norepinephrine level was markedly increased (12.5 +/- 1.43 vs 8.28 +/- 0.82 nmol/L). Our results fail to indicate an independent adverse effect of ESRD on LV function.

Biosynthesis of the potent carcinogen 7,12-dimethylbenz[a]anthracene.

Earlier studies from this laboratory of the metabolism of 7,12-dimethylbenz[a]anthracene (DMBA) and of benzo[a]pyrene as well as studies of mutagenic and carcinogenic activity of some of the metabolic products led to the concept that a necessary first step in carcinogenesis by most alkyl substituted polycyclic hydrocarbons is biotransformation to a meso-anthracenic hydroxyalkyl metabolite, whereas most hydrocarbons lacking alkyl substituents undergo a bio-alkylation substitution reaction in the mesoanthracenic position(s) or L-region as a necessary first step in carcinogenesis. According to this unified hypothesis, all strong polycyclic hydrocarbon carcinogens must either, themselves, bear a meso-anthracenic alkyl substituent or else undergo a bio-alkylation substitution reaction in vitro and in vivo. Here we report that the weak carcinogen benz[a]anthracene undergoes meso-anthracenic methylation by S-adenosyl-L-methionine (SAM), in the presence of a rat liver cytosol preparation, in vitro, to form DMBA and presumably the moderately active carcinogens 7-methylbenz[a]anthracene and 12-methylbenz[a]anthracene. These compounds are substrates for further L-region methylation to form the strong carcinogen, DMBA.

Sulfotransferase-mediated chlorination of 1-hydroxymethylpyrene to a mutagen capable of penetrating indicator cells.

Methylated polycyclic aromatic hydrocarbons are common in the human environment. Many of them are stronger carcinogens than their purely aromatic congeners. They may be metabolized to benzylic alcohols. We report here on biochemical and toxicological characteristics of 1-hydroxymethylpyrene (HMP), a typical representative of this class of compounds. Rat liver cytosol, fortified with 3'-phosphoadenosine-5'-phosphosulfate, converted HMP into its sulfate ester (HMPS), HMPS bound covalently to isolated DNA. In physiological buffer at 37 degrees C, HMPS had a half-life of 2 min, the major decomposition product being HMP. Thus, cyclic activation is possible. When Cl- anions were present at physiological concentrations, an additional reaction product of HMPS, 1-chloromethylpyrene (ClMP), could be identified on the basis of its chromatographic properties and its mass spectrum, using the authentic standard for comparison. ClMP was shorter-lived in buffer than HMPS. ClMP reacted with DNA, the adduct pattern in the 32P-postlabeling analysis being similar, or identical, to that of HMPS. ClMP proved to be a very potent mutagen in Salmonella typhimurium, whereas HMPS, and HMP in the presence of a sulfate-conjugating system, showed strong mutagenicity only when Cl- or Br- ions were present in the exposure buffer. It is concluded that HMPS is capable of reacting with DNA, but is hampered in its distribution by membrane barriers.(ABSTRACT TRUNCATED AT 250 WORDS)

Metabolism of 3-methylcholanthrene in rat liver cytosol.

The present study investigates the metabolism of the potent carcinogen 3-methylcholanthrene in rat liver cytosol preparations. Three metabolites of 3-methylcholanthrene were characterized by HPLC and GC/MS analysis. These metabolites were identified as 1-hydroxy-3-methylcholanthrene, 1-keto-3-methylcholanthrene and cholanthrene. The results of the present study, taken together with earlier studies, suggests that the first step in the metabolic activation of 3-methylcholanthrene is hydroxylation at the 1-position, the most easily oxidized reactive center in the molecule.

Bioalkylation of dibenz[a,b]anthracene in rat liver cytosol.

Previous studies by other investigators have established that L-region methyl derivatives of dibenz[a,h]anthracene (DBA) were more carcinogenic than the parent hydrocarbon. The bioalkylation of DBA was investigated by incubating the hydrocarbon with rat liver cytosol fortified with S-adenosyl-L-methionine (SAM) in 0.1 M phosphate buffer (pH 7.4) for 1 h at 37 degrees C in air. The reaction was stopped by the addition of cold acetone and the mixture extracted with ethyl acetate and washed with water. The organic phase was evaporated and the residue dissolved in methylene chloride for analysis by reverse phase high performance liquid chromatography (HPLC) and gas chromatography/mass spectroscopy GC/MS. Products were found that were indistinguishable from 7-methyl-DBA and 7,14-dimethyl-DBA, 7-hydroxymethyl-DBA, 7-hydroxymethyl-14-methyl-DBA, and 7,14-dihydroxymethyl-DBA. The results suggest that unsubstituted carcinogenic hydrocarbons are preprocarcinogens that react with SAM in liver cytosol preparations, to form alkyl substituted procarcinogens, which are more potent than the corresponding preprocarcinogens.

Thrombotic risk in patients with aortic bioprostheses.

Thrombosis of Mosaic aortic valve bioprostheses occurring at more than one month after surgery occurs in 0.8% (95% CI 0.33-1.67%) of patients. In the two cases reported here, each patient had risk factors for thrombus formation, namely severe left ventricular impairment in one patient, while the other patient was heterozygous for prothrombin variant G20210A. The cases were treated successfully, by thrombolytic therapy with streptokinase in the first case, and by repeat aortic valve replacement in the second case. Thrombosis of bioprosthetic valves in the aortic position is rare, and a period of anticoagulation postoperatively does not invariably protect against this serious complication. In conclusion, patients with risk factors for thrombus formation should be considered for long-term anticoagulation.

Immunoassay detection of drugs in racing horses: detection of ethacrynic acid and bumetanide in equine urine by ELISA.

We have raised antibodies and developed one-step enzyme-linked immunosorbent assays (ELISA) for the diuretics ethacrynic acid and bumetanide as part of a panel of pre- and post-race tests for high potency drugs in racing horses. These ELISA tests are rapid (completed within one hour), sensitive, and can be read by eye. The ELISA detects ethacrynic acid at a drug concentration for half-maximal inhibition (I-50) of about 2.5 ng/mL for the parent drug. After dosing horses intravenously with 5 mg ethacrynic acid per horse, the parent drug or its metabolites are detectable in urine for at least 8 hours. The bumetanide ELISA has an I-50 for the parent drug of about 2.0 ng/mL and will detect bumetanide or its metabolites for about 8 hours in urine after intravenous administration of a 1.7-mg dose per horse. Both antibodies are relatively specific for each drug and do not cross-react with other commonly used diuretics or other acidic compounds often found in post-race equine urine samples. Ethacrynic acid and bumetanide are potent diuretics suspected of being illegally substituted for furosemide in certain racing jurisdictions. Development of these rapid, sensitive, and simple tests for these agents will allow more effective pre- and post-race control of the use of these agents in racing horses. Both tests have recently uncovered several "positives" for these medications in a midwestern racing jurisdiction.

Narcotic analgesics, their detection and pain measurement in the horse: a review.

Narcotic analgesics produce pharmacological effects by interacting with specific opiate receptors. At least five major types of opiate receptors have been recognised. These include mu (morphine) and kappa (ethylketazocine) receptor types. Narcotic analgesics which interact with mu receptors produce locomotor and autonomic stimulation at doses that produce little or no analgesia. Therefore, use of these drugs as analgesics in equine medicine has not been very satisfactory. Theoretical considerations suggested that the role of kappa agonists in equine analgesia be investigated. Using a pure kappa agonist, U-50, 488H, good analgesia was produced in the horse with little or no locomotor stimulation or autonomic effects. These data suggest that kappa agonists may be superior analgesics for clinical use in the horse. On the other hand, the locomotor stimulant effects of mu agonist analgesics enable their use as illegal medications. Specifically, these agents produce a good running response, signs of central nervous stimulation and analgesia, all potentially useful effects in a racehorse. Regulatory control of most narcotic analgesics can be obtained by high performance thin layer chromatographic screening. However, effective screening for the fentanyls and small doses of etorphine can only be achieved by use of immunoassay.

Equine urine pH: normal population distributions and methods of acidification.

Our investigation of the urine of grazing horses at the University of Kentucky shows that the mean pH level is about 7.9, and if their diet is supplemented with grain, it is about 7.4. There appears to be no significant effect of time of day or year on urine pH levels in horses. However, horses taken from pasture and supplemented with grain in a stalled environment show a slight decrease in urine pH. Additionally, we investigated the effects of storage on pH levels. Equine urine samples appear to be quite stable with regard to pH for 48h, but then show a marked increase. Urine pH can have a great effect on the urine concentration of some drugs and therefore, uncertainties can arise when data generated in grazing horses are compared or extrapolated to racing horses whose urine pH can be quite low. In an effort to simulate the drop in urine pH seen in some racing horses, we examined the effects of ammonium chloride, ascorbic acid, lactic acid and methionine on urine pH in research horses. Both oral and intravenous routes of administration were used. Although all agents tested showed varying degrees of efficacy, oral administration of ascorbic acid proved to be the safest and most effective agent to model the rapid acidification of urine seen in post race samples.

Hordenine: pharmacology, pharmacokinetics and behavioural effects in the horse.

Hordenine is an alkaloid occurring naturally in grains, sprouting barley, and certain grasses. It is occasionally found in post race urine samples, and therefore we investigated its pharmacological actions in the horse. Hordenine (2.0 mg/kg bodyweight [bwt]) was administered by rapid intravenous (iv) injection to 10 horses. Typically, dosed horses showed a flehmen response and defecated within 60 secs. All horses showed substantial respiratory distress. Respiratory rates increased about 250 per cent and heart rates were approximately double that of resting values. All animals broke out in a sweat shortly after iv injection, but basal body temperature was not affected. These effects were transient, and the animals appeared normal within 30 mins of dosing. Treated horses were tested in a variable interval responding apparatus 30 mins after dosing and no residual stimulation or depressant effects of hordenine were apparent. Animals dosed orally with 2.0 mg/kg bwt of hordenine showed no changes in heart rate, respiratory rate, basal body temperature or behaviour. After iv injection of hordenine, (2.0 mg/kg bwt) plasma reached a maximum value of about 1.0 micrograms/ml, and declined thereafter in a biexponential fashion. Kinetics of plasma concentration satisfied the concept of a two compartment open system, with an alpha-phase half-life of about 3 mins, and a beta-phase half-life of about 35 mins. Total urinary concentrations of hordenine (free and conjugated) peaked at about 400 micrograms/ml, and then declined exponentially to background levels by 24 h after dosing.(ABSTRACT TRUNCATED AT 250 WORDS)

Drug interactions in the horse: effects of chloramphenicol, quinidine, and oxyphenbutazone on phenylbutazone metabolism.

The plasma half-life of phenylbutazone in horses was not increased after pretreatment with chloramphenicol or quinidine, but was increased after oxyphenbutazone. This increased plasma half-life after oxyphenbutazone is consistent with observations in other species and suggests that oxyphenbutazone inhibits the metabolism of phenylbutazone in horses. Lack of inhibition of phenylbutazone metabolism in the horse by chloramphenicol and quinidine is inconsistent with results obtained in other species.

Pharmacology of procaine in the horse: procaine esterase properties of equine plasma and synovial fluid.

Procaine added to whole equine blood or diluted plasma was hydrolyzed with half times of approximately 9 and 12 minutes, respectively, at 37 C. This hydrolytic activity was sensitive to heating and physostigmine, but did not affect procainamide. At pharmacologic concentrations of procaine, the rate of the hydrolytic reaction depended directly on the concentrations of plasma or procaine in the system and was less in whole blood than in plasma. These properties are consistent with hydrolysis being due to plasma esterases operating at less than saturating procaine concentrations. These esterases were also inhibited cooling, sodium fluoride, or arsenite. Synovial fluid had approximately 20% of the procaine esterase activity of plasma. Comparison of hydrolytic activities of plasmas from Thoroughbred, Standardbred, and other breeds of horses showed statistically significant differences in the rates at which individual plasmas hydrolyzed procaine. A frequency distribution of these rates showed unimodal distribution, indicating that all horses tested may be regarded as members of a single population.

Pharmacology of narcotic analgesics in the horse: quantitative detection of morphine in equine blood and urine and logit-Log transformations of this data.

Morphine was detected in equine biological fluids by a combination of liquid-liquid extraction and column chromatography, followed by derivatization and gas-liquid chromatographic assay, using electron capture detector. Recovery of morphine from the equine biological samples was poor. However, despite an overall recovery of less than 20%, this method had a detection limit of 0.2 ng/ml. Addition of 5,000 U of bovine liver beta-glucuronidase/ml of urine enabled detection of the drug in urine for up to 144 hours after horses were given 0.1 mg of morphine/kg of body weight. Morphine was found for at least 24 hours in serum samples. An adaptation of logit-log transformation of gas-liquid chromatographic data for linearization over 3 log units suggested a simple adaptation to existing semiautomated data handling systems.

Pharmacology of procaine in the horse: a preliminary report.

Rapid intravenous injection of 1 g of procaine hydrochloride in Thoroughbred mares produced variable signs of central nervous system excitation for as long as 4 minutes. Plasma concentrations of procaine were similarly variable and transient, decreasing with a half-life of approximately 25 minutes. In vitro, plasma from freshly collected equine blood hydrolyzed procaine with a half-life of approximately 7.5 minutes. This hydrolysis was apparently due to plasma esterases. Penicillin, when added free or complexed as procaine-penicillin, did not protect procaine against hydrolysis by these plasma esterases at pH 7.4.

Pharmacologic effects and detection methods of methylated analogs of fentanyl in horses.

Pharmacologic effects of alpha-methylfentanyl and 3-methylfentanyl, analogs of fentanyl, were investigated in mares. The ability of an 125I-labeled fentanyl radioimmunoassay (125I-RIA) to detect these methylated fentanyl analogs in individual and pooled urine samples from horses was evaluated. Also, the ability of 7 fentanyl antibodies to react with fentanyl and fentanyl derivatives (sufentanil, alfentanil, and carfentanil) was investigated. Mares were studied in a locomotor test to determine the amount of stimulation methylated fentanyl analogs might induce. Two mares each were given alpha-methylfentanyl at 1, 2, 4, 8, or 13 micrograms/kg of body weight, IV, or 3-methylfentanyl at 0.4, 0.7, or 1 microgram/kg IV. The cross-reactivity of sufentanil, alfentanil, carfentanil, alpha-methylfentanyl, and 3-methylfentanyl with 7 fentanyl antibodies was studied, using the 125I-RIA. All fentanyl analogs, with the exception of alfentanil, cross-reacted well with a C1 antibody raised to fentanyl. Less satisfactory cross-reactivity was determined with 6 other antibodies raised to fentanyl derivatives. When the C1 antibody was combined with an iodinated analog to fentanyl, good detectability of alpha-methylfentanyl and 3-methylfentanyl, in terms of fentanyl equivalents, was obtained from urine samples of dosed mares. The ability of the 125I-RIA to detect methylated fentanyl analogs in forensic urine samples pooled in groups of up to 20 samples was evaluated. When these methylated analogs were administered to mares in doses that induced measurable locomotor stimulation, the analog's presence was readily detected in individual or pooled samples.

High-sensitivity radioimmunoassay screening method for fentanyl.

A radioiodinated analog of fentanyl was synthesized for use with a commercially available radioimmunoassay for fentanyl. The sensitivity of the modified assay was at least 100 times greater than that of the original assay. Using this modified assay, concentrations of fentanyl as low as 1 pg/ml of fentanyl or fentanyl equivalents in equine urine were detected. Doses of fentanyl 100 times smaller than the minimum dose for a pharmacologic effect were detectable and a pharmacologically effective dose of fentanyl was detectable for up to 96 hours or more. The high sensitivity of the assay indicated that large numbers of urine samples (ie, 10 to 20) probably could be pooled and screened simultaneously, which would result in an economical analysis for fentanyl in the urine of horses after a race. Sufentanil and its metabolites also were detectable, using this assay, but at only about 1% of the efficiency at which fentanyl was detectable.

Gas/liquid chromatographic analysis of pemoline in biological fluids using electron capture detection.

An analytical gas/liquid chromatographic (GLC) protocol is described for the quantitation of pemoline in biological fluids of the horse. Plasma samples containing known quantities of pemoline and its analog as an internal standard (IS) were deproteinized with 5-sulfosalicylic acid, heated at 80 degree C, and centrifuged. 5-Phenyl-2,4-oxazolidinedione, the hydrolytic product of pemoline in acid medium, was extracted with dichloromethane (DCM). The organic layer was in turn re-extracted with 1% NaHCO3. The aqueous layer was acidified with HCI, and re-extracted with DCM, which was evaporated to dryness. The resulting residue was methylated with ethereal diazomethane. The methylated dione was dissolved in benzene, and analyzed with a gas/liquid chromatograph equipped with a tritiated scandium foil (Sc3H) electron capture detector (ECD). Urine samples to which pemoline was added were hydrolyzed with hydrochloric acid and carried through the analytical procedure in a manner similar to the plasma, except that the urine was further washed with lead acetate solution prior to the sodium bicarbonate extraction. The lower limits of detection were found to be 0.05 microgram/ml for plasma and 0.1 microgram/ml for urine when 1.0 ml of sample was used. This procedure can be used for pemoline detection control in international sporting events.

Mefanamic acid blood and urine levels in the horse determined by derivative gas-liquid chromatography-electron capture.

Mefenamic acid is extracted from biological fluids and is acylated with pentafluoropropionic anhydride to form a derivative possessing high electron affinity. The derivative is analyzed by gas-liquid chromatography with an electron capture detector. The method is particularly valuable for determining drug levels in blood where small sample and/or drug concentrations are available.

Efficacy of testing for illegal medication in horses.

The efficacy of testing for illegal drugs in race horses was surveyed by evaluating 27 questionnaires received from 28 racing jurisdictions polled. Large variations in the number of samples tested and drugs detected were reported. Some jurisdictions reported only illegal medications, whereas others also reported permitted medications. To facilitate comparison, stimulants, depressants, local anesthetics, narcotic analgesics, and tranquilizers were classified as hard drugs. Other drugs, which are legal in some jurisdictions, were classified as soft. To evaluate the efficacy of testing, positive test results were compared for hard drugs only. Positive test results varied from zero in some jurisdictions for some years to 14.8/1,000 samples tested for one small jurisdiction in one year. The mean rates over the years 1975 to 1983 varied from 0.2 to 6.5/1,000, with a modal positive test result of about 1/1,000. Beside the fact that prerace blood testing is less effective than is postrace urine testing, no cause for these variations in the positive test results could be identified. The positive test results also were compared for jurisdictions with differing medication rules for phenylbutazone (PBZ). Jurisdictions that did not allow PBZ had a mean positive test result for hard drugs of about 1.3 +/- 0.9/1,000 samples tested. Jurisdictions that allowed more liberal use of PBZ had a mean positive test result for hard drugs of about 1.3 +/- 1.0/1,000 samples tested. Seemingly, the presence of PBZ in equine forensic samples did not reduce the ability of forensic laboratories to detect the use of hard or illegal drugs.