Excretion of creatinine, sodium sulfanilate (SS), and phenolsulfonphthalein (PSP) was studied in healthy goats. In conscious goats, mean (+/- SEM) inulin clearance was 2.26 +/- 0.08 ml/min/kg of body weight. Endogenous creatinine clearance, 1.97 +/- 0.09 ml/min/kg, underestimated inulin clearance (P < 0.01), probably because of the presence of noncreatinine chromogens in caprine plasma. The estimated renal clearance of PSP was 6.88 +/- 0.39 ml/min/kg, whereas the estimated renal clearance of SS was 3.71 +/- 0.39 ml/min/kg. Both exceeded inulin clearance (P < 0.01), confirming renal tubular secretion of both compounds. In 6 anesthetized goats, exogenous creatinine clearance and SS clearance exceeded inulin clearance (P < 0.05). Results of stop-flow experiments documented secretion of creatinine and ss by the peoximal portion of the caprine nephron. Plasma half-life of PSP in uninephrectomized goats exceeded that in intact goats (20.2 +/- 1.5 min vs 11.9 +/- 0.7 min; P < 0.01). Similarly, plasma half-life of SS was greater in goats after uninephrectomy (58.2 +/- 6.2 min vs 30.4 1.2 min; p < 0.01).

An ion chromatographic method was used to simultaneously determine nitrate and nitrite ions in biological samples. Ultrafiltration was used to produce a protein-free filtrate. Chloride interferences were eliminated by precipitation as the silver salt. Detection limits and average recoveries were 0.5 mg/L and 102% for nitrate and 0.2 mg/L and 78% for nitrite, respectively. Nitrate concentration was 2.1 +/- 1.8 mg/L and 4.9 +/- 0.8 mg/L in serum and ocular fluid of healthy cattle, respectively; nitrite was not detected. A severe case of nitrate poisoning in cattle was described and used to study the concentrations of nitrate and nitrite in samples obtained under natural conditions. Nitrate concentration of acutely poisoned cattle was 35% lower in ocular fluid at 158.1 +/- 51.4 mg/L, than in serum at 256.3 +/- 113.4 mg/L. Nitrite was not detected, because of the long processing time (> 3 hours) required for samples obtained in the field. A gradual decrease in ocular fluid nitrate of 29.4% at 24 hours, 25.9% at 36 hours, 51.6% at 48 hours, and 73.2% at 60 hours was observed; however, concentrations remained diagnostically significant (73.2 mg/L) 60 hours after death. Twenty-four hours after poisoning, the serum nitrate concentration of severely ill (52.7 +/- 51.9 mg/L) and moderately affected (12.4 +/- 5.7 mg/L) cattle that survived was indicative of the severity of clinical signs previously observed. Nitrate in serum and ocular fluid was stable in samples stored for 24 hours at 23 C, 1 week at 4 C, and 1 month at -20 C.

Concentrations of total, free, and esterified carnitine were determined in plasma, liver, and skeletal muscle from cats with idiopathic hepatic lipidosis and compared with values from healthy cats. The mean concentrations of plasma, liver, and skeletal muscle total carnitine; plasma and skeletal muscle free carnitine; and plasma and liver esterified carnitine were greater (P < 0.05) in cats with idiopathic hepatic lipidosis than in control cats. The mean for the ratio of free/total carnitine in plasma and liver was lower (P < 0.05) in cats with idiopathic hepatic lipidosis than in control cats. These data suggest that carnitine deficiency does not contribute to the pathogenesis of feline idiopathic hepatic lipidosis.

Evoked potentials were induced by transcranial stimulation and recovered from the spinal cord, and the radial and sciatic nerves in six dogs. Stimulation was accomplished with an anode placed on the skin over the area of the motor cortex. Evoked potentials were recovered from the thoracic and lumbar spinal cord by electrodes placed transcutaneously in the ligamentum flavum. Evoked potentials were recovered from the radial and sciatic nerves by surgical exposure and electrodes placed in the perineurium. Signals from 100 repetitive stimuli were averaged and analyzed. Waveforms were analyzed for amplitude and latency. Conduction velocities were estimated from wave latencies and distance traveled. The technique allowed recovery of evoked potentials that had similar characteristics among all dogs. Conduction velocities of potentials recovered from the radial and sciatic nerves suggested stimulation of motor pathways; however, the exact origin and pathway of these waves is unknown.

Stimulation of bovine alveolar macrophages with calcium ionophore A23187 resulted in marked production of leukotriene (LT)B4 and a lesser increase in thromboxane (TX)B2, whereas opsonized zymosan (OPZ) resulted in production of TXB2 and relatively small increases in LTB4 and prostaglandin (PG)F2 alpha. Alveolar macrophages incubated with recombinant bovine interferon-gamma or lipopolysaccharide, and subsequently stimulated with A23187 or OPZ, had altered arachidonic acid metabolism, producing markedly increased amounts of TXB2 and PGF2 alpha, and slightly increased LTB4. Incubation of alveolar macrophages with lipopolysaccharide had a more profound effect on the increased amounts of TXB2 and PGF2 alpha, observed in response to stimulation with A23187 or OPZ, than did incubation with interferon-gamma. Alveolar macrophages incubated with recombinant bovine interferon-alpha 1-1 also produced slightly increased amounts of LTB4 when stimulated with A23187 or OPZ. Altered arachidonic acid metabolism by alveolar macrophages exposed to interferons and lipopolysaccharide may contribute to the development of pulmonary inflammation, such as in the early stages of bacterial pneumonia following viral infections that induce interferon production.

Atracurium besylate, a nondepolarizing neuromuscular blocking agent, was administered as an infusion to 8 anesthetized cats in which neuromuscular blockade was assessed, using the train-of-four response. Once 50% depression of the first-twitch (T1) response was achieved, the infusion was held constant for 60 minutes before being discontinued and the recovery time was determined. The time for recovery was recorded as the time for the train-of-four ratio (T4 ratio) to increase from 50% to 75%. After recovery, atracurium infusion was reinstituted and the cats were again maintained for 60 minutes at 50% depression. A single bolus of gentamicin sulfate (2.0 mg/kg of body weight) was administered IV, and the infusion was continued for another 60 minutes before it was discontinued and the time for recovery was recorded. Within 1 minute of gentamicin administration, the mean +/= SD T1 response decreased from 49 +/- 5% to 33 +/- 8% of baseline and the T4 ratio decreased from 28 +/- 19% to 14 +/- 11%. Peak effect occurred at 5 minutes, with a T1 response of 29 +/- 6% of baseline and a T4 ratio of 13 +/- 12%. By 60 minutes after gentamicin administration, the T1 response had increased to 38 +/- 7% of baseline and the T4 ratio had increased to 21 +/- 13%. The time for recovery significantly (P less than 0.03) increased from 9.9 +/- 3.4 minutes during the control study to 18.1 +/- 10.7 minutes during the gentamicin study. In this study, gentamicin potentiated the neuromuscular blockade induced by atracurium and increased the recovery time. Residual blockade, observed after gentamicin administration was reversed with edrophonium.

Immunoglobulin reactions to Salmonella dublin in serum and milk from 4 groups of lactating cows were measured by an indirect ELISA. The groups consisted of (1) cows that were natural carriers of S dublin in the mammary gland, (2) experimentally infected cows that did not become carriers, (3) cows inoculated with a commercial S dublin bacterin, and (4) cows used as S dublin-negative controls. Milk and serum samples were obtained at monthly intervals. Models for predicting carrier status were developed by use of stepwise logistic regression. Independent variables consisted of serum and milk IgG and IgM titers to S dublin lipopolysaccharide and a ratio of IgG to IgM. The utility of a single sample vs multiple samples obtained at 1-month or 2-month intervals was tested by comparison of goodness-of-fit X2 P values for 8 models predicting carrier status. Immunoglobulin reactions specific to S dublin were a significant predictor of carrier status (P < 0.001). Serum IgG titers specific for S dublin were the most important variable for predicting carrier status. Two serum IgG titers to S dublin obtained 2 months apart was a better predictor of carrier status than measurement of the IgG:IgM ratio from a single serum sample. Immunoglobulin recognizing S dublin epitopes also were detected in milk samples. In milk, performing 2 ELISA 60 days apart to determine IgG and IgM reactions to S dublin appeared to be useful for the prediction of carrier status, but was not as accurate as models for serum immunoglobulin reactions.

The in vitro antimicrobial activities of aditoprim (AP), a new dihydrofolate reductase (DHFR) inhibitor, trimethoprim (TMP), sulfadimethoxine (SDM), sulfamethoxazole (SMX), and combinations of these drugs against some porcine respiratory tract pathogens were determined by use of an agar dilution method. The minimal inhibitory concentrations (MIC) of these agents were determined twice against Bordetella bronchiseptica (n = 10), Pasteurella multocida (n = 10), and Actinobacillus pleuropneumoniae (n = 20) strains isolated from pigs suffering from atrophic rhinitis or pleuropneumonia. All B bronchiseptica strains were resistant to AP and TMP. The MIC50 values of AP and TMP for P multocida were 0.25 and 0.06 microgram/ml, respectively, and for A pleuropneumoniae, 1 and 0.25 microgram/ml, respectively. The MIC50, values of SDM and SDM for B bronchiseptica were 4 and 1 microgram/ml, respectively; for P multocida, 16 and 8 microgram/ml, respectively; and for A pleuropneumoniae, 16 and 8 microgram/ml, respectively. The investigated combinations of the DHFR inhibitors and the selected sulfonamides had synergism for the A pleuropneumoniae strains; the MIC90 values of the combinations were less than or equal to 0.06 microgram/ml. Potentiation was not observed for the B bronchiseptica and the P multocida isolates. The MIC of the combinations against B bronchiseptica and P multocida corresponded respectively to the concentrations of the sulfonamides and the DHFR inhibitors in the combinations. For A pleuropneumoniae, 2 types of strains were used (25% of serotype 2 and 75% of serotype 9). Type-2 strains had lower susceptibility than type-9 strains to AP and TMP as well as to SDM and SMX (at least a fourfold difference in MIC between the 2 types of strains). The MIC of the combinations were similar for the 2 types of strains.

Absorption rate and plasma and fat disposition of lindane after various lindane percutaneous treatments in shorn and unshorn sheep were investigated. To analyze data with a deconvolution method, IV administration was performed to determine the basic pharmacokinetic values of lindane in sheep. After IV administration, the steady state volume of distribution was very high (8.07 +/- 3.60 L/kg of body weight), and the mean residence time was long (28.1 +/- 11.7 hours). Deconvolution analysis indicated that lindane absorption was continuous until 33 to 41 days after spraying with a 0.025% lindane solution. Total amount of absorbed lindane in shorn (15,171 +/- 4,463 microgram/kg) sheep was about twice that in unshorn (7,615 +/- 3,128 microgram/kg) sheep; from deconvolution analysis, it was calculated that the time required for 50% of the available dose to be absorbed was between 115 and 179 hours. After percutaneous lindane administration, the fat concentration was compared with the available lindane dose. The apparent half-life of lindane elimination in fat was 225 +/- 47.4 hours, which is similar to the value calculated for the absorption rate constant. By comparing fat and plasma concentrations, it was calculated that for a mean plasma concentration of 5 ng/ml, the fat lindane concentration was 1.65 +/- 0.87 microgram/g (ie, lower than the generally accepted tolerance level of 2 microgram/g).

Serum samples obtained from 40,927 swine at various locations in North Carolina between Aug 1, 1987 and July 31, 1988, were tested for antibodies to Trichinella spiralis, using an ELISA based on a larval T spiralis excretory-secretory antigen. In the ELISA, samples were considered to have positive results if the optical density (OD) reading was equal to or 5 times greater than the mean OD value of 4 negative-control sera from trichina-free swine. Of the 40,927 serum samples tested, 154 (0.38%) were positive by ELISA; the rate for breeding swine was 0.35% (105/30,162), and the rate for cull swine was 0.45% (49/10,765). Of the 49 seropositive samples from cull swine, 11 were from out of the state, 22 had no identification, and 16 were known to originate from North Carolina. Seropositivity had a bimodally seasonal distribution, with peaks in March and September. There was no difference between the mean age of seropositive and seronegative swine, but males were at greater risk for seropositivity than were females. Pigs from lots with < 100 sera tested were at increased risk for seropositivity, as were pigs from the central coastal region of North Carolina.