Serum from dogs with surgically induced renal impairment was incorporated into the medium for erythroid bone marrow cultures. A significant correlation was found between serum activities of erythropoietin and numbers of erythroid colony-forming units grown in culture. Serum creatinine concentrations had no correlation, and serum parathyroid hormone activities had a negative correlation with numbers of erythroid colony-forming units that was below the level of significance. Purified 1-84 parathyroid hormone added to bone marrow cultures was found to be stimulatory to erythroid colony-forming unit growth in higher concentrations, but decreased the number of burst-forming units. Unmeasured substances in the canine serum appeared to have a greater effect on the canine erythroid bone marrow cultures than did creatinine or parathyroid hormone values.

Hybridomas producing monoclonal antibodies to Ehrlichia risticii were developed to provide a means of molecular investigation of the biochemical and immunopathologic characteristics of the organism. All of 6 stable monoclonal antibodies obtained were IgG isotypes. The ascitic fluid titers induced by the hybridomas ranged from 10(2) to 10(7). Competitive binding experiments conducted by ELISA and binding of labeled protein A to antigen-antibody complexes indicated competition among monoclonal antibodies. Two monoclonal antibodies (HybI and 14D4) were reactive in an indirect fluorescent antibody test; these antibodies also bound a maximum of labeled protein A, indicating recognition of epitopes on the surface of the ehrlichiae. Protein specificity of monoclonal antibodies could not be demonstrated with western blot procedure. HybI monoclonal antibody, however, did precipitate the 28 kD protein from 125I-surface-labeled ehrlichiae and was shown to be specific to E risticii on the basis of nonreactivity with E sennetsu, using the indirect fluorescent antibody test. By use of the different monoclonal antibodies as probes, more definitive molecular studies now will be feasible.

We evaluated the deformability of bovine platelets and contrasted the effects of pharmacologic and thermal perturbations on cytoskeletal structure of human and bovine platelets. Platelets were aspirated into micropipettes (0.7 to 0.8 micromoles in diameter) by stepwise increments in tension. The resulting lengths of the cell extensions were recorded. The cell extensions aspirated from bovine platelets were shorter than the extensions drawn from human platelets. Disassembly of the circumferential microtubule coil allowed human platelets to pass through the pipette, but the same treatments only slightly increased the deformability of bovine platelets. Alteration of the actin filament cytoskeleton caused increased mechanical fragility of human platelets. In contrast, even the combined use of microtubule and actin filament-disrupting agents only modestly increased the deformability of bovine platelets and did not cause premature fragmentation of the cells. Unusual cytoskeletal structure, absence of an open canalicular system, and disparity in granule size may all contribute to the variance in deformability between the platelets of the 2 species. Reduced cell deformability may impair bovine platelet surface interactions by diminishing the ease of cell spreading and formation of areas of contact between the platelet and other cell surfaces.

Dermal microfilariae recovered form specimens obtained from umbilical and cervical sites of cattle infected with adult Onchocerca gutturosa alone or with adults of O gutturosa and O lienalis were measured and compared with uterine microfilariae obtained directly from gravid female worms of each species. Uterine microfilariae of O gutturosa were longer than dermal microfilariae obtained from cattle harboring only adults of O gutturosa. Dermal microfilariae were recovered from umbilical and cervical sites in these cattle. Those found at the cervical site had lengths equal to or greater than lengths of microfilariae recovered from the umbilical site. There was a significant (P less than 0.0001) shift in length across populations of microfilariae of O gutturosa from various sites in its bovine host, with a progressive decrease in length between microfilariae recovered from the worm's uterus, microfilariae from the cervical dermis, and microfilariae from the umbilical dermis, respectively. A similar direct comparison was not possible for microfilariae of O lienalis, because none of the cattle was infected with only adult worms of this species. In an indirect comparison, microfilariae of O lienalis were identified at the umbilicus, but their presence in the cervical region could not be determined unequivocally because of confounding of microfilariae length by concurrent infection with O gutturosa. Uterine microfilariae from O lienalis were longer than uterine microfilariae of O gutterosa, although a degree of overlap in the range of measurements existed between species.

Serum uric acid concentrations were determined in horses known to be carriers of combined immunodeficiency gene(s) and in presumed noncarrier horses. Uric acid concentrations were significantly higher (P < 0.005) in carrier horses than in presumed noncarrier horses. However, there was some overlap in serum uric acid concentrations between carrier and presumed noncarrier horses.

Tracheal mucus transport rates were measured over a 10-minute period in 20 healthy horses twice in 24 hours. The mean rate was 1.93 +/- 0.55 cm/min on day 1 and 1.99 +/- 0.49 cm/min 24 hours later. The mean difference between day 1 and day 2 (0.06 +/- 0.42 cm/min) was not significant (P = 0.55). The range on day 1 was 1.12 to 2.9 cm/min and 1.11 to 2.89 cm/min on day 2.

Ruminal microorganisms in cattle at a Florida agriculture research station did not have the ability to detoxify leucaena by degradation of 3-hydroxy-4(lH)-pyridone (3,4,-DHP), but a DHP isomer (2,3-DHP) was degraded in some cattle. Cattle with microorganisms that degraded 2,3-DHP were mostly Senepol cattle imported from St. Croix, US Virgin Islands, where leucaena is an indigenous species. Hereford cattle at the research station in Florida generally did not degrade 3,4-DHP or 2,3-DHP. An experiment was conducted in which a pure culture of 3,4-DHP-degrading bacteria was inoculated into Hereford cattle (with ruminal fistula) grazing leucaena. The bacteria successfully colonized the rumen of recipient cattle and persisted through the following winter when there was no leucaena in the diet.

Anaplasma marginale was propagated in a tick cell line derived from Dermacentor variabilis embryos. The rickettsial organism was identified and monitored in culture by transmission electron microscopy and the indirect immunofluorescence technique, using specific monoclonal antibodies. Inoculation of the embryonic tick cell line with midguts of infected adult ticks (culture 1), nymphal ticks (culture 2) and adult ticks that were infected as nymphs and dissected as adults (culture 3) resulted in 3 continuous cultures of A marginale. Culture 1 had been maintained through 22 passages over a 11-month period; cultures 2 and 3 had been maintained for 18 passages over a 9-month period. Growth of A marginale in the cell line began in the area of the nuclear membrane at approximately 4 days after inoculation or transfer. Thereafter, the organisms were observed in inclusions scattered throughout the cytoplasm of the host cells. Maximal growth of the organism occurred at 7 to 14 days, after which numbers of inclusions rapidly decreased to minimal or undetectable levels. The organism began new cycles of growth with each 1:5 to 1:10 split and transfer of the host cells. Electron microscopy of recently infected cells revealed a morphology of the organism that closely resembled that observed in marginal bodies of infected erythrocytes. After several passages, A marginale organisms had a varied morphology and resembled the organism described in midgut cells of naturally infected ticks. Substitution of adult bovine serum for fetal bovine serum and adjustment of the pH of the medium from 6.9 to 7.4 resulted in several-fold increases in amount of growth and reduced the period required to reach maximal growth to a predictable time of 5 to 7 days. The importance and potential of this method of continuous laboratory propagation of A marginale are discussed.

Sixteen primiparous sows were bred and fed either a control ration (n = 8) or a diet containing purified zearalenone (n = 8; 1 mg/kg of body weight) from days 7 to 10 after breeding. On day 7 after breeding, the jugular vein of each sow was cannulated and blood was collected at 20-minute intervals for 4 hours before feeding and 4 hour after feeding. On day 10 after breeding, blood samples were collected from 4 control sows and 4 zearalenonefed sows at 20-minute intervals for 4 hours before collection of blastocysts. A similar blood sampling schedule was followed for the remaining 4 control and 4 zearalenone sows on day 14 after breeding. On day 10 after breeding, spherical blastocysts were recovered from all control sows and from 3 of 4 zearalenone-treated sows. Average diameter of blastocysts from zearalenone-treated sows were similar to that of control sows. On day 14 after breeding, blastocysts were recovered from all control sows and 3 of 4 zearalenone-treated sows. Blastocysts from the control sows were filamentous, whereas blastocysts from zearalenone-treated sows were fragmented and contained foci of necrosis. Incidence of luteinizing hormone (LH) secretory spikes per sow was less (P less than 0.01) in zearalenone-treated sows (0.25 +/- 0.25/4 h) than control sows (1.75 +/- 0.25/4 h) on day 10 after breeding. Incidence of follicle-stimulating hormone (FSH) secretory spikes was simillar (P = 0.45) among treatments on days 7, 10, and 14 after breeding. Mean serum concentrations of LH were less on day 10 (P = 0.07) and day 14 (P less than 0.01) in zearalenone-treated sows than in control sows (3.3 +/- 0.2 ng/ml vs 6.2 +/- 1.3). These data indicate that administration of zearalenone on days 7 to 10 after breeding altered secretory patterns of serum LH during days 10 and 14 after breeding, which may have contributed to the death of blastocysts by day 14 after breeding.

Periosteal autografts were obtained from the medial aspect of the proximal portion of the tibia, and perichondrial autografts were obtained from the sternum. Using arthroscopic visualization, each autograft was placed as a loose body into 1 tarsocrural joint in 6 young horses (2 to 4 years old). Horses were hand-walked daily, starting the day after surgery, for a total of 6 h/wk for 8 weeks. Eight weeks after autograft implantation, radiographs were taken of each tarsocrural joint and were interpreted with regard to mineralization in the transplanted autografts. Autografts were then surgically removed, and examined macroscopically and microscopically for viability, size, and production of chondroid tissue. All autografts appeared viable and most had evidence of growth. Longest-by-shortest axis value, cross-sectional area, and perimeter were greater in perichondrial autografts than in their periosteal counterparts in 3 horses, but the difference was not significant. Neochondrogenesis was observed in 5 of 6 periosteal grafts and in 1 of 6 perichondrial grafts. Futhermore, the amount of chondroid tissue produced in periosteal autografts was significantly (P less than 0.05) greater than that produced in the 1 perichondrial graft. The chondroid tissue produced by periosteal autografts had morphologic and matrical staining properties similar to those of hyaline cartilage.