Increase in serum digoxin concentration produced by quinidine does not increase the potential for digoxin-induced ventricular arrhythmias in dogs.

Chronic treatment of dogs with digoxin alone, quinidine alone and digoxin in combination with quinidine was initiated in dogs to assess changes in arrhythmogenic potential associated with the quinidine-induced increase in serum digoxin concentration observed during combined digoxin and quinidine treatment. The arrhythmogenic potential of digoxin was evaluated through the use of the acetylstrophanthidin (AcS) tolerance test. AcS was infused at a rate of 5 micrograms/kg/min until ventricular arrhythmias occurred during a drug-free period and during chronic treatment with digoxin, quinidine and digoxin plus quinidine.

Nocardia asteroides sepsis of the knee.

Nocardia asteroides as an infecting agent has been an increasingly identified pathogen in humans, especially in immunosuppressed hosts. The Nocardia organisms as a cause of septic arthritis have been very unusual and in all previously reported cases have occurred in immunosuppressed patients. This is a report of two additional patients, one of whom has had no history of immunosuppression either before infection or subsequent to treatment and resolution of the infection.

Altered acoustic reflectance on two-dimensional echocardiography as an early predictor of myocardial infarct size.

P6 area of increased acoustic reflectance was readily observed by 2-dimensional echocardiography (2-D echo) in the acutely ischemic canine myocardium. Fifteen mongrel dogs subjected to closed-chest coronary artery occlusion were used to test the hypothesis that these areas of altered acoustic reflectance were predictors of subsequent myocardial infarction (MI). Each dog was studied by 2-D echo in short-axis views of the left ventricle at 4 levels before and after coronary artery occlusion.

Fallibility of Griess (nitrite) test.

The Griess (nitrite) test is a simple, inexpensive, and rapid method for detecting bacteriuria. However, a working knowledge of its limitation should be considered during its interpretation.

Activated coagulation time test: a convenient monitor of heparinization for dogs used in cardiovascular research.

The usefulness of the activated coagulation time test to monitor heparin effect was studied by administering varying intravenous doses of heparin to six mongrel dogs. Using the activated coagulation time test, a dose response relationship and half-life for heparin action were determined in each dog. It was observed that a heparin dose of 200 units/kg provided less than the generally accepted minimal anticoagulant effect of an activated coagulation time of 180 seconds, while a dose of 500 units/kg produced adequate anticoagulation.

New and rapid method for detection of pyuria by leukocyte esterase reaction.

A method for a rapid detection of leukocytes in the urine is available in the form of a "dipstick." The reaction (color change) occurs within one minute and has a high index of reliability.

The inability of isoproterenol or propranolol to alter the lateral dimensions of experimentally induced myocardial infarcts.

The relationship between the blood flow pattern immediately following coronary artery occlusion and the resulting infarct 24 hours later was studied in dogs treated with isoproterenol (0.5 micrograms/kg/min for 2 hours) or with propranolol (2 mg/kg every 6 hours). The coronary artery of a closed chest dog was perfused via a special cannula with arterial blood.

Acute effects of intravenous furosemide administration on serum digoxin concentration.

The effect of intravenous (IV) furosemide (2.5 mg/kg) on serum digoxin concentration, urine flow rate, and myocardial contractility and rhythm was studied in normal dogs and dogs treated with digoxin. Furosemide IV to animals which had not been receiving digoxin resulted in increased urine flow rate from 0.

Antiarrhythmic activity of amitriptyline analogues in conscious dogs after myocardial infarction: cyproheptadinium methiodide.

The antiarrhythmic effects of amitriptyline (1), its secondary amine metabolite nortriptyline (2), as well as cyclobenzaprine (3) and cyproheptadine (4), tertiary amine analogues of 1, were studied in conscious dogs 24 h after myocardial infarction. Since the sedative side effect of 4 presents a potential problem for its clinical use, a quarternary derivative of 4, cyproheptadine methiodide (5), was prepared and its effects also studied in this model. Complete conversion to a normal sinus rhythm occurred in all animals studied after cumulative doses of 1700 micrograms/kg (6.

Effects of N-nitrosopiperidine substitutions on mutagenicity in Drosophila melanogaster.

N-Nitrosopiperidine (NP) and various derivatives were fed to Drosophila melanogaster males over a wide concentration range in order to assess their mutagenic potency in the induction of X-linked recessive lethals and chromosome loss. NP was effective in inducing lethals, as were its halogen and methyl-substituted derivatives, with the exception of 2,6-dimethyl NP. (Methyl substitutions at the alpha carbon atoms reduce or eliminate mutagenic activity.

The antiarrhythmic action of amitriptyline on arrhythmias associated with myocardial infarction in dogs.

The antiarrhythmic activity of amitriptyline, a tricyclic antidepressant, was evaluated in anesthetized dogs 24 h after coronary occlusion, during the period of spontaneous ventricular arrhythmias. In all experiments amitriptyline was administered i.v.

Influence of alterations in sinus rate on determination of drug-induced changes in ventricular automaticity.

The interrelationship between drug-induced changes in heart rate and drug-induced alterations in ventricular automaticity was studied in dogs with intact conduction systems and dogs with surgically-induced complete heart block. The effects of epinephrine (0.5 microgram-kg-1-min-1) and propranolol (1.

Effects of derivatives of cyclic amp and cyclic gmp on contraction force of cat papillary muscles.

Right ventricular kitten papillary muscles were incubated with dibutyryl adenosine 3',5'-monophosphate (dbcAMP) at varying concentrations as low as 1 X 10(-4)M. A positive inotropic effect was observed with all concentrations of dbcAMP. Concomitant administration of 5 X 10(-4)M monobutyryl guanosine 3',5'-monophosphate (mbcGMP) and 1-2 X 10(-4)M dbcAMP prevented the inotropic response observed when dbcAMP was used alone.