peer reviewed

Cytosolic assay was used to detect gonadal steroid receptors in brain tumor tissue from 6 dogs and 2 cats. For 4 samples, the maximal number of binding sites and the equilibrium dissociation constant were calculated, using Scatchard analysis. The concentration of receptor protein that was discovered was similar to that detected in hormone-sensitive tumors.

The vascular permeability of the ocular fundus, alterations in the coagulation system, and plasma concentrations of thromboxane B2 (TXB2) and 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) were studied in dogs following intradermal inoculation with 5 x 10(5) TCID50 of Rickettsia rickettsii. Twenty-four to 48 hours after the onset of fever and rickettsemia, multifocal areas of retinal vasculitis were evident, which corresponded to areas of altered vascular permeability demonstrated by fluorescein angiography. The number and intensity of retinal vessels with sodium fluorescein leakage peaked during the second week after inoculation, and retinal vascular permeability remained altered during the third week of infection, well past the phase of clinical and clinicopathologic recovery. Development of retinal vasculitic foci was associated with thrombocytopenia, increased concentrations of circulating fibrinogen, and slight prolongation of activated partial thromboplastin time. Increased concentrations of fibrin/fibrinogen degradation products were detected in 4 of 9 dogs. Despite the degree of vascular endothelial damage evident on fluorescein angiographic and histologic studies in these dogs, plasma TXB2 and 6-keto-PGF1 alpha concentrations were not increased.

Norepinephrine (NE) and epinephrine (EPI) collected from dogs were sequentially and temporally measured in blood and plasma at 24 C. Heparin and EDTA anticoagulants, in combination with reduced glutathione and EDTA as a preservative, were also compared. Norepinephrine and EPI concentrations were measured by high-pressure liquid chromatography with electrochemical detection. In heparinized plasma, NE and EPI concentrations were relatively stable in the absence or presence of preservative after 24 hours at 24 C. In EDTA plasma, NE and EPI values were less stable when compared with those in heparinized samples. Norepinephrine concentrations in EDTA plasma without preservative decreased by 163.2 +/- 8.88 pg over 24 hours, compared with an 86.6 +/- 7.92 pg loss of NE in heparinized plasma. The degradation of EPI in EDTA plasma without preservative was also twofold greater, compared with that in heparinized plasma. Addition of preservative had no stabilizing effect on NE or EPI in heparinized or EDTA plasma. During long-term storage at -70 C, plasma NE and EPI values decreased < 0.6 and < 0.1 pg/d, respectively. Norepinephrine and EPI values were stable in heparinized blood for 6 hours but decreased to < 25% and < 6% of initial base line values, respectively, when plasma separation was delayed 24 hours.

Serum tumor necrosis factor (TNF) activity wasquantitated in 8 horses given an IV infusion of endotoxin (0.03 microgram of lipopolysaccharide/kg of body weight, from Escherichia coli 55:B5) in 0.9% NaCl solution over 1 hour. Serum TNF activity was likewise measured in 6 horses given only 0.9% sterile NaCl solution at the same rate. The duration of serum TNF activity was determined, and serum TNF activity was correlated with clinical and laboratory changes during the induced endotoxemia. Horses had no serum TNF activity prior to endotoxin administration, but geometric mean serum TNF activity was significantly higher from 1 to 4 hours after the start of the infusion. In response to endotoxin, horses seemed depressed, had signs of mild to moderate abdominal pain, developed tachycardia and fever, and had leukopenia followed by leukocytosis. Association between serum TNF activity and temperature, heart rate, attitude abnormality score, and WBC count of horses given endotoxin was significant. Serum TNF activity had a significant positive linear correlation with attitude abnormality and heart rate and a negative linear correlation with the WBC count during endotoxemia. Geometric mean serum TNF activity peaked approximately 1.5 hours prior to mean peak fever, and these data were significantly correlated. Results of this study suggest that TNF is an important mediator of endotoxemia in horses.

Viral RNA oligonucleotide fingerprinting was used to compare genetic relationships among pestiviruses originating from ovine or bovine host species. Ovine pestiviruses, including reference border disease virus and 2 border disease isolates originating from natural pestivirus infections of sheep, appeared to have a more distant genetic relationship among themselves than with certain bovine pestiviruses. A closer genetic relatedness was evident between border disease virus and 3 noncytopathic bovine pestiviruses, including Draper bovine viral diarrhea virus (BVDV), a BVDV isolate that originated from aborted bovine fetuses, and a virus that was isolated from the serum of a calf that had a chronic BVDV infection. Four noncytopathic bovine viruses, including Draper BVDV and 3 field isolates, were closely related. Reference Oregon C24V BVDV, a cytopathic virus, was closely related to only 1 of the 7 noncytopathic viruses in this study.

Ten adult dogs (5 Beagles and 5 mixed-breed dogs) were inoculated IV with canine platelets containing Ehrlichia platys. Inclusions and morulae of E platys developed in platelets of infected dogs at 10 to 14 days after inoculation, followed by marked thrombocytopenia at 14 to 21 days. Parasitemia and marked thrombocytopenia recurred at 24 to 28 days after inoculation. Increased numbers of megakaryocytes were observed in marrow aspirate smears from infected dogs, indicative of regenerative thrombocytopenia. Prior to infection, platelet-rich plasma from these dogs was determined to have similar aggregatory response to arachidonate. After infection with E platys, the aggregatory response of platelet-rich plasma to collagen or 3 dilutions of adenosine diphosphate was evaluated. A statistically significant (P < 0.05) inhibition of platelet aggregatory response to the lowest dilution of adenosine diphosphate was detected for mixed-breed dogs, whereas aggregation responses were unchanged in Beagles. Results indicate that platelet activation may occur in dogs with acute ehrlichial infection.

Hybridomas secreting monoclonal antibodies (MAB) to transmissible gastroenteritis virus (TGEV) were produced by fusion of SP2/0 myeloma cells and splenic lymphocytes of BALB/c mice immunized with the virulent cell-passaged Miller strain of TGEV. The MAB secreted by these hybridomas were partially characterized; 4 of them (MA4, MA5, MH11, MB2) had high-neutralization titer for TGEV. The remaining 7 (MC6, MD9, ME5, MG5, MF2, ME9, MG7) did not neutralize TGEV at 1:25 dilution. All 4 neutralizing and 2 of the nonneutralizing MAB reacted with the E2 protein of TGEV in a radioimmunoprecipitation assay. The remaining 5 MAB reacted with the E1 protein of TGEV. Reactivity of the MAB was tested in an indirect immunofluorescent assay with 3 cell culture-adapted strains of TGEV (Miller, Purdue, and Illinois) and 13 wild-type isolates of TGEV. Neutralizing MAB reacted with all 13 wild-type isolates and the 3 cell culture-adapted strains of TGEV. In contrast, nonneutralizing MAB that reacted with the Miller strain of TGEV varied in their reactivity with the wild-type TGEV isolates. Reactivity of neutralizing MAB was also tested, using plaque-reduction neutralization assays with Miller, Purdue, and Illinois strains and 5 wild-type isolates. All 4 neutralizing MAB neutralized the 8 virus isolates, but the neutralization titer was higher with the homologous virus than with the heterologous virus isolates. However, neutralization titers of the 4 neutralizing MAB were 4 to 16 times higher for the homologous Miller strain of TGEV than for the heterologous Illinois and Purdue strains, and were 4 to 1,000 times higher than for the wild-type isolates. Extensive antigenic heterogeneity was observed among TGEV isolates on epitopes recognized by the nonneutralizing MAB directed against either E1 or E2 protein.

In a controlled study, malignant murine P815 mastocytoma cells exposed in vitro to distilled and deionized water died as a result of progressive swelling, degranulation, and membrane rupture. A 90% mean cell death occurred when cells obtained directly from culture were exposed to deionized water for 2 minutes. Of 6 cryopreserved malignant murine cell lines, which included Cloudman S91 melanoma, CMT-93 rectum carcinoma, MMT-06052 mammary carcinoma, and S-180 Sarcoma, only P815 mastocytoma and YAC-1 lymphoma were significantly (P < 0.05) affected by hypotonic shock; Cloudman S91 melanoma cells were the most resistant. Mastocytoma cells were selectively killed by hypotonic solution, and lymphoma cells were also killed by isotonic saline solution. Local mast cell tumor (MCT) recurrence and percentage survival were evaluated in 12 cats (21 MCT) and 54 dogs (85 MCT) subjected to surgery alone or local infiltration of deionized water as an adjunct to surgery. Of all 16 incompletely excised MCT in cats, there was no local recurrence following injection. Four mast cell tumors (2 cats) regressed after being injected in situ. In dogs with clinical stage-I MCT, local recurrence was detected in 50% (5/10), but with injection after incomplete excision, local MCT recurrence was significantly (P < 0.05) less (6.6%, 1/15). Percentage recurrence was significantly (P < 0.05) less and survival significantly greater when incompletely excised grade-II MCT were injected. Mean follow-up period after surgery in cats and dogs was 35 and 23.4 months, respectively.

Plasma glucocorticoid concentrations and blood gas values were determined for 6 days in 47 newborn calves that had been subjected to various obstetrical procedures at term. Concentrations of glucocorticoids were uniformly high at birth (70 to 103 ng/ml). Increasing degrees of acidosis were accompanied by increasing glucocorticoid concentrations in plasma. Plasma glucocorticoid concentrations decreased sharply during the first 6 hours after delivery and reached a plateau at 48 hours after birth (14 to 21 ng/ml). The latter was taken as an indication that adaptation had been achieved. Calves subjected to severe pulling had higher glucocorticoid concentrations at birth (110.4 ng/ml) than calves requiring no assistance (88.3 ng/ml), calves requiring only slight assistance (83.8 ng/ml), or calves that had been delivered by cesarean section (82.9 ng/ml).