The effects of phencyclidine pretreatment on amphetamine-induced behavior and c-Fos expression in the rat.

Previous data demonstrate that a single injection of phencyclidine enhances amphetamine-induced behaviors 24 h later, suggesting that the delayed effects of a single dose of phencyclidine may produce a schizophrenia-like state in animals. These behavioral changes were accompanied by altered patterns of c-Fos induction, suggesting possible neurochemical correlates to the observed behaviors. Because investigations into PCP's ability to model schizophrenia have found that the effects of repeated, or subchronic, PCP administration differ according to the dose and administration paradigm, this study sought to determine whether single and subchronic PCP exposure produce different effects on amphetamine-induced behaviors and c-Fos induction. No differences were observed between these administration paradigms; both single and subchronic PCP exposure enhanced amphetamine-induced c-Fos in the striatum, decreased c-Fos in the prefrontal cortex, and decreased the number of cage-crossings. However, the observation that PCP pretreatment affected c-Fos induction in the same manner observed previously while having an opposite effect on amphetamine-induced behavior suggests that these behavioral and neurochemical effects are dissociated.

Pharmacokinetics of allopurinol in Dalmatian dogs.

The pharmacokinetics of allopurinol were studied in Dalmatian dogs. Eight dogs were given allopurinol orally at a dose of 10 mg/kg for seven doses prior to sample collection. After a period of at least two weeks, four of these dogs and four additional Dalmatians were later given a single intravenous (i.v.) dose of allopurinol (6 mg/kg) prior to sample collection. Allopurinol was found to follow first-order absorption and elimination kinetics. In the i.v. kinetic study, the elimination constant (Kel) = 0.31 +/- 0.03 per h, the half-life (t1/2) = 2.22 +/- 0.20 h, the initial concentration (C0) = 5.26 +/- 0.34 micrograms/mL and the specific volume (Vd) = 1.14 +/- 0.07 L/kg. Clearance of allopurinol was estimated to be 0.36 +/- 0.03 L/kg.h. In the oral kinetic study, the absorption rate constant (Kab) = 1.06 +/- 0.13 per h, the elimination rate constant (Kel) = 0.26 +/- 0.01 per h, the absorption half-life (t1/2ab) = 0.66 +/- 0.06 h, and the elimination half-life (t1/2el) = 2.69 +/- 0.14 h. Peak plasma concentrations (Cmax) = 6.43 +/- 0.18 micrograms/mL were obtained within 1 to 3 h (mean time of maximum concentration (Tmax) = 1.9 +/- 0.1 h). The volume of distribution corrected by the fraction of dose absorbed (Vd/F) was estimated to be 1.17 +/- 0.07 L/kg. Good agreement was obtained between mean kinetic parameters in the oral and i.v. studies. There was little variation between individual dogs in the i.v. study, whereas the rate of absorption and elimination of orally administered allopurinol was more varied among individual dogs. Because of this, and the fact that the magnitude of hyperuricosuria varies among Dalmatians, it is not possible to specify an exact dose of allopurinol that will effectively lower the urinary uric acid concentration to acceptable values in all Dalmatians with hyperuricosuria; rather, the dose must be titrated to the needs of each dog.

Urolithiasis in Dalmations: 275 cases (1981-1990).

From July 1, 1981 to December 31, 1990 the Urinary Stone Analysis Laboratory, School of Veterinary Medicine, University of California received 292 urinary calculi from 275 Dalmations (14 females, 14 episodes; 261 males, 278 episodes). The mean age of dogs at the time of the first episode of calculus formation was 4.5 years for males and 5.5 years for females. Bacteria were isolated from 22 of 49 calculi (45%). The bacteria were gram-positive with 2 exceptions; coagulase-positive staphylococci accounted for 62.5% of the isolates. Polarized light microscopy was used to determine the mineral content of the calculi. One hundred ninety three calculi were 100% urate; 78 calculi contained > or = 50% urate in 1 or more layers and were classified as mixed urate calculi; 7 calculi contained < 50% urate in all layers; and 14 calculi contained no urate. The secondary minerals most commonly encountered in mixed urate calculi were struvite (77%, 60 of 78 calculi), and oxalate (17%, 13 of 78 calculi). There were 65 struvite-containing calculi, 16 oxalate-containing calculi, 7 apatite-containing calculi, 5 silica-containing calculi, and 1 calculus specimen was composed of 100% cystine. The risk of forming urate-containing calculi was high in Dalmations, whereas the risk of forming calculi containing other minerals was consistently lower in Dalmations than in other breeds. X-ray diffraction and high pressure liquid chromatography were performed on all calculi from dogs known to have been given allopurinol (n = 19).(ABSTRACT TRUNCATED AT 250 WORDS)

Cystine-containing urinary calculi in dogs: 102 cases (1981-1989).

One hundred and seven cystine-containing urinary calculi from 1 female and 101 male dogs were analyzed. Cystine-containing calculi accounted for 2% (107 of 5,375) of all canine urinary calculi submitted to the urinary stone analysis laboratory from July 1981 through December 1989. Male dogs that formed cystine calculi were compared with 3 other canine populations to determine whether certain breeds were apparently at increased or decreased risk for cystine calculus formation. In one or more of 3 population comparisons, significantly increased risk of cystine calculus formation was found in Mastiffs, Australian Cattle Dogs, English Bulldogs, Chihuahuas, Bullmastiffs, Newfoundlands, Dachshunds, Basenjis, Australian Shepherd Dogs, Scottish Deerhounds, Staffordshire Terriers, Miniature Pinschers, pitbull terriers, Welsh Corgis, Silky Terriers, and Bichon Frises. Significantly low risk of cystine calculus formation was found in German Shepherd Dogs, Poodles, Schnauzers, and mixed-breed dogs.

Insulinoma and subclinical peripheral neuropathy in two dogs.

Two dogs with diffuse, subclinical polyneuropathy associated with insulinoma are reported. Seizures were the dominant sign of central nervous system disease. One dog had clinical signs of facial nerve paralysis. Lesions in selected appendicular and cranial nerves included a mixture of demyelination, remyelination, and axonal degeneration. The incidence (range: 18-47%) of these changes far exceeded that of comparable nerves from six control dogs (range 0-11%). Myopathic and electrodiagnostic findings were compatible with the nerve changes.

Staphylococci in canine urolithiasis: species identification, using a commercially available tray micromethod.

Fifty-one coagulase-positive staphylococcal isolates from canine urinary calculi or from the urine of dogs with documented urolithiasis, and 17 coagulase-positive staphylococcal isolates from human beings and cattle were identified by a commercially available tray micromethod, as well as by conventional methods. Canine isolates had previously been classified as Staphylococcus aureus on the basis of a positive tube coagulase test. After 5 hours' incubation, the tray method identified all 51 canine urolithiasis isolates as S intermedius, rather than S aureus. All human and bovine isolates were identified as S aureus. Conventional methods supported these findings.