Conventionally raised Chinese Meishan and European Large White pigs were intragastrically challenge exposed with 2. 1 X 10(10) enterotoxigenic Escherichia coli strains bearing colonization factor K88, 987P, F41, or F41 plus K99. In response to challenge exposure with the K88-positive (K88+) organisms, 96% of Large White pigs died within 48 hours, whereas none of the Meishan pigs died. Both breeds of pigs had similar susceptibility to strains bearing 987P or F41. Lastly, Meishan pigs were found to be more susceptible than Large White pigs to a strain expressing K99 and F41. In pigs with diarrhea, challenge-exposure strains intensively colonized the jejunum (10(8) to 10(10) bacteria/g of tissue) and, to less extent, the duodenum (except K88+ strain, which comprised 10(8)/g). In most cases, jejunal concentrations of the challenge-exposure strains were substantially lower in pigs that did not have diarrhea. Half the resistant Meishan pigs eliminated the K88+ strain from the intestines. Colostral antibody titer that agglutinated challenge-exposure strains did not differ between Meishan and Large White gilts. Results indicate that resistance of pigs to the K88+ strain did not extend to enterotoxigenic strains bearing other well-known factors. They indicate, in addition, that genetic resistance to K88+ strains described in pigs in Europe may exist in pigs in China.

Tear samples were collected from 1 eye of each of 40 cows, 27 sheep, 5 goats, and 5 human beings. Additionally, 10 bovine tear samples were pooled and concentrated. Spectrophotometric assays, using Micrococcus lysodeikticus, were performed on each sample to detect lysozyme activity expressed in hen egg lysozyme (HEL) equivalents. Lysozyme activity was not detected in tears of cows, but 158.8 +/- 159.3 mg of HEL/ml was detected in tears of sheep, 220.7 +/- 37.5 mg of HEL/ml in tears of goats, and 216.3 +/- 86.2 mg of HEL/ml in tears of human beings. In pooled bovine tear samples, lysozyme activity was not detected on plate assay and lysozyme protein was not detected on polyacrylamide gel electrophoresis, column chromatography, or immunoelectrophoresis with rabbit anti-bovine tear antibodies. On the basis of these observations, we concluded that the basic ocular protective mechanism in bovine tears is not lysozyme. Other antibacterial proteins such as lactoferrin, transferrin, complement, or beta-lysin may, therefore, be of primary importance in protecting the bovine eye.

Unbound or free cortisol constitutes a small fraction of total plasma cortisol, but is believed to represent the biologically active portion of this circulating glucocorticoid. We tested the hypothesis that the percentage free cortisol was altered in plasma from dogs with hyperadrenocorticism, which could account for a greater target tissue response to this circulating hormone. The percentage free cortisol in plasma samples from human beings, healthy dogs, and dogs with hyperadrenocorticism was estimated, using centrifugal ultrafiltration-dialysis. Total cortisol concentrations were determined by use of radioimmunoassay. Total cortisol concentrations appeared greater in plasma from human beings than in plasma from either group of dogs. However, the percentage free cortisol was lower in plasma from human beings, resulting in a calculated concentration of free cortisol that was quite similar between plasma from human beings and healthy dogs. Total plasma cortisol concentrations were greater (P < 0.01) in samples from dogs with hyperadrenocorticism (190 +/- 113 nmol/L; mean +/- SD) than in healthy dogs (102 +/-85 nmol/L), but the percentage free cortisol was not different between these 2 groups (dogs with hyperadrenocorticism, 16 +/- 9%; healthy dogs, 13 +/- 6%). However, plasma free cortisol concentrations (product of total and the percentage of free cortisol) were greater (P < 0.01) in samples from dogs with hyperadrenocorticism (36 +/- 41 nmol/L) than in those from healthy dogs (16 +/- 9 nmol/L). Significant (P < 0.001) positive linear relationships were found between total cortisol concentrations and percentage free cortisol in plasma samples from healthy dogs and dogs with hyperadrenocorticism. Furthermore, the slope of these lines was not different between the 2 groups, providing no evidence for alterations in cortisol binding associated with hyperadrenocorticism. The higher total cortisol concentrations in dogs affected with this disease do, however, result in greater concentrations of free cortisol in circulation, contributing to the development of clinical signs observed in this disease.

An automated reticulocyte counting method that used a flow cytometer and the nucleic acid staining dye, thiazole orange, was developed. Anticoagulated (EDTA) blood specimens were suitable for flow cytometric reticulocyte counting when stored at 4 C for 96 hours after collection. Thiazole orange-stained samples were stable for 5.5 hours after staining when stored capped at 20 C and protected from light. Flow cytometric and manual microscopic reticulocyte counts were compared for counts in the 0.27 to 5.32% range (as determined by flow cytometry) and 0.10 to 4.90% range (as determined by 1 technician). Although the results of flow cytometric analysis generally correlated well (r = 0. 821) with manual counts, there was poor correlation between the procedures for counts less than or equal to 2.0% (r < 0.272). Linearity of flow cytometric counts over the range 0.27 to 14.46% was excellent (r = 0.999). Within-run precision of flow cytometric counts (% coefficient of variation [CV] = 3 to 5) was superior to manual microscopic counts obtained by one technician (% CV = 19 to 23) and to manual microscopic counts, which were an average of counts done by 3 technicians (% CV = 8 to 18). Comparable flow cytometric counts were obtained by counting 50,000 or 100,000 blood cells in the flow cytometer.

The hematologic and pathologic effects of orally administered L-tryptophan and indoleactic acid and of L-tryptophan administered IV were studied in ponies. Sixteen adult Shetland ponies were allotted into 4 experimental groups. Group 1 consisted of 5 ponies (1-5) given 0.6 g of tryptophan/kg of body weight in a water slurry via stomach tube. Group 2 included 4 ponies (6-9) given 0.35 g of tryptophan/kg orally. Group-3 ponies (10-13) were given 0.35 g of indoleacetic acid/kg orally. Group 4 consisted of 3 ponies (14-16) given a single 4-hour IV infusion of 0.1 g of tryptophan/kg. Restlessness, increased respiratory rate, hemolysis, and hemoglobinuria were detected in 4 of the 5 group-1 ponies. Only pony 7 in group 2 developed hemolysis, hemoglobinuria, and a significant increase in respiratory rate. Renal pathologic lesions, consistent with hemoglobinuric nephrosis, were seen in ponies 2, 4, 5, and 7. Bronchiolar degeneration was evident in 4 of 9 ponies given tryptophan orally. The importance of these respiratory lesions was unknown. Clinical or pathologic abnormalities were not noticed in the ponies of groups 3 and 4. Mean plasma tryptophan values increased significantly in groups 1 and 2 at 6 hours after dosing. A second peak of tryptophan was detected in both groups at 12 hours. Values returned to predose values by 48 hours. Plasma indole and 3-methylindole concentrations were detectable in only 2 ponies (4 and 7). In vitro incubations of cecal fluid from ponies 6, 8, and 9 yielded a percentage conversion of tryptophan to indole of 16.75%, 5.84%, and 7.96%, respectively. 3-Methylindole was not produced. These results suggested that indole was the major metabolite of orally administered tryptophan in these ponies.

Samples of sera were obtained from 5,725 cows in a semiclosed herd. In each of the preceding 7 years, the herd was vaccinated against bovine viral diarrhea (BVD) with killed virus. Neutralizing antibody tests were done on all samples of sera, using cytopathic virus, BVD-TGAC virus, that was antigenically distinct from the vaccine virus. Most samples of sera had high titers of neutralizing antibodies against BVD-TGAC virus. In 48 samples of sera, neutralizing antibodies were not detected against BVD-TGAC virus, but were detected against the vaccine virus. Neutralizing antibodies against selected noncytopathic BVD viruses were not detected in several samples of serum that had neutralizing antibodies against the vaccine virus and BVD-TGAC virus. Noncytopathic BVD virus was isolated from sera obtained from 3 cows < 4 years old. Two cows were available for further testing, and persistent infection with BVD virus was confirmed in both cows. The BVD viruses isolated from those cows were not neutralized by several samples of sera. Immunoprecipitation of polypeptides induced by the vaccine virus was done with selected samples of serum. Two patterns of immunoprecipitated viral-induced polypeptides were identified. One pattern was consistent with exposure of cows with live virus. The other pattern was consistent with exposure of cows with only the killed virus vaccine.

In these studies, the effects of recombinant human interleukin 2 (rHuIL-2) were examined on in vitro tumor cytotoxicity by canine blood lymphocytes obtained from peripheral vessels through use of a chromium release microcytotoxicity assay. Cytotoxic activity by lymphokine-activated killer cells was significantly increased, compared with that by untreated lymphocytes in a dose-dependent manner. The maximal effect was attained with 300,000 IU of rHuIL-2/ml. Lymphokine-activated killing also was dependent on the duration of incubation with rHuIL-2. After 1 day of rHuIL-2 incubation, cytotoxicity was significantly increased, compared with that of untreated lymphocytes. Of the 3 times examined, cytotoxicity peaked after 3 days of rHuIL-2 incubation. High levels of cytotoxic activity were still present at 7 days of incubation. Numbers of granular lymphocytes increased over the times examined. These results demonstrate functional and morphologic changes in canine peripheral blood lymphocytes obtained from peripheral vessels after incubation with rHuIL-2 in a dose- and time-dependent manner.

Phagocytic and nitroblue tetrazolium (NBT) reductive activities of blood neutrophils from 19 Holstein heifers were measured by light microscopic and spectrophotometric methods, respectively. These functional properties of neutrophils correlated well (r = 0.64) and varied significantly (P < 0.05) among animals studied. Variations in phagocytosis and NBT reductive activities attributable to the source of sera were determined in experiments in which cells from the same cows and zymogen particles opsonized with heat-inactivated autologous or homologous sera were used. Variations attributable to the source of cells were determined in experiments in which cells from different cows and particles opsonized with pooled sera from all the cows were used. Most of the variation in phagocytic properties and NBT reductive activities was attributable to the source of cells (ie, each cow). The source of sera contributed slightly to the variation in NBT reductive activities, but not to the phagocytic properties. These results support the concept of functional heterogeneity of neutrophils among cows.

Twenty-four specific-pathogen-free Beagles were each given 50 cysticerci of Taenia pisiformis that had been harvested from experimentally infected rabbits. Quantitative fecal egg counts and fecal screening for recovery of passed segments were performed on postinoculation days 56 through 70. Twenty-three of 24 dogs fed cysticerci developed patent infections. The 23 dogs with patent infections were assigned to 1 of 2 groups and treated with nitroscanate or a placebo 60 days after inoculation. Egg counts in the treated dogs had markedly decreased by the second day after treatment, and by the sixth day after treatment, segments were not found in the feces of any of the treated animals. The control dogs continued to pass eggs and segments in their feces throughout the 9 days after treatment. The dogs were euthanatized and necropsied 70 days after being inoculated. At necropsy, the mean number of scolices recovered from control dogs was 24.6, the mean number of scolices recovered from treated dogs was 0.25. Worms recovered from the control dogs were intact, gravid cestodes. Efficacy of treatment with nitroscanate at a mean dosage of 56 mg/kg of body weight was 98.9%.

The functional characteristics of polymorphonuclear leukocytes (PMN), considered to be the first line of host defense against infections, from rhesus macaques confirmed to have simian retrovirus (SRV)-induced simian acquired immunodeficiency syndrome (SAIDS), were evaluated. The PMN from SRV antibody-positive macaques without clinical signs were chemotactically responsive. Their phagocytic and killing capabilities were normal, and their cell membranes were highly deformable. However, PMN from SRV antibody-positive macaques and with persistent lymphadenopathy, as well as having at least 3 of the 11 common clinical signs of SAIDS, were chemotactically nonresponsive. Their phagocytic and killing capabilities were compromised, and their cell membranes were rigid and nondeformable. In general, PMN from macaques with clinically confirmed SAIDS were functionally deficient. The results are similar to those obtained in other retroviral infections and can be clinically significant, because the host defense deficiency may be responsible for the recurrent and opportunistic infections in SAIDS.