A preliminary study to evaluate the immune responses induced by immunization of dogs with inactivated Ehrlichia canis organisms

Ehrlichia canis is an intracellular pathogen that causes canine monocytic ehrlichiosis. Although the role of antibody responses cannot be discounted, control of this intracellular pathogen is expected to be by cell mediated immune responses. The immune responses in dogs immunized with inactivated E. canis organisms in combination with Quil A were evaluated. Immunization provoked strong humoral and cellular immune responses, which were demonstrable by Western blotting and lymphocyte proliferation assays. By Western blotting antibodies to several immunodominant E. canis proteins were detected in serum from immunized dogs and antibody titres increased after each immunization. The complement of immunogenic proteins recognized by the antisera were similar to those recognized in serum from infected dogs. Upon challenge with live E. canis, rapid anamnestic humoral responses were detected in the serum of immunized dogs and primary antibody responses were detected in the serum from control dogs. Following immunization, a lymphocyte proliferative response (cellular immunity) was detected in peripheral blood mononuclear cells (PBMNs) of immunized dogs upon stimulation with E. canis antigens. These responses were absent from non-immunized control dogs until after infection with live E. canis, when antigen specific-lymphocyte proliferation responses were also detected in the PBMNs of the control dogs. It can be thus concluded that immunization against canine monocytic ehrlichiosis may be feasible. However, the immunization regimen needs to be optimized and a detailed investigation needs to be done to determine if this regimen can prevent development of acute and chronic disease.     

Source regions of summertime ozone and haze episodes in the eastern United States

During the summer of 1979, the mobile Atmospheric Research Laboratory (ARL) was sited near the Louisiana Gulf Coast to monitor the concentrations of air contaminants in air masses moving northward from the Gulf. Using the ARL data in conjunction with O₃ and visibility measurements across the entire eastern United States as well as synoptic meteorological data and satellite photographs, major source areas were identified. The haze which was observed on the Louisiana Gulf Coast appears to be primarily due to aged sulfate aerosols. The evidence presented strongly suggests that the sulfates were largely due to SO₂ emissions in the northeastern and midwestern United States. The haze initially formed over and downwind of these source areas and was transported to the Gulf Coast area. In the last two episodes, the haze was subsequently transported back to the Midwest source region. Elevated levels of O₃ were also associated with the haze. Again, the Northeast and Midwest appear to be the most significant source areas for the regional O₃ episodes. Occasionally, O₃ formed from emissions in the east Texas area also appear to affect a large portion of the Gulf Coast. In addition, each episode appeared to have a significant stratospheric air component based on⁷Be measurements. All three episodes followed the passage of upper levels troughs which produce stratospheric intrusions due to tropopause folding.     

Pharmacokinetics and plasma concentrations of acetylsalicylic acid after intravenous, rectal, and intragastric administration to horses

Six healthy adult horses (5 mares and 1 stallion) were given a single dose of acetylsalicylic acid (ASA), 20 mg/kg of body weight, by intravenous (IV), rectal, and intragastric (IG) routes. Serial blood samples were collected via jugular venipuncture over a 36-h period, and plasma ASA and salicylic acid (SA) concentrations were determined by high-performance liquid chromatography. After IV administration, the mean elimination rate constant of ASA (± the standard error of the mean) was 1.32 ± 0.09 h⁻l, the mean elimination half-life was 0.53 ± 0.04 h, the area under the plasma concentration-versus-time curve (AUC) was 2555 ± 98 μg · min/mL, the plasma clearance was 472 ± 18.9 mL/h/kg, and the volume of distribution at steady state was 0.22 ± 0.01 L/kg. After rectal administration, the plasma concentration of ASA peaked at 5.05 ± 0.80 μg/mL at 0.33 h, then decreased to undetectable levels by 4 h; the plasma concentration of SA peaked at 17.39 ± 5.46 μg/mL at 2 h, then decreased to 1.92 ± 0.25 μg/mL by 36 h. After rectal administration, the AUC for ASA was 439.4 ± 94.55 μg · min/mL and the bioavailability was 0.17 ± 0.037. After IG administration, the plasma concentration of ASA peaked at 1.26 ± 0.10 μg/mL at 0.67 h, then declined to 0.37 ± 0.37 μg/mL by 36 h; the plasma concentration of SA peaked at 23.90 ± 4.94 μg/mL at 4 h and decreased to 0.85 ± 0.31 μg/mL by 36 h. After IG administration, the AUC for ASA was 146.70 ± 24.90 μg · min/mL and the bioavailability was 0.059 ± 0.013. Administration of a single rectal dose of ASA of 20 mg/kg to horses results in higher peak plasma ASA concentrations and greater bioavailability than the same dose given IG. Plasma ASA concentrations after rectal administration should be sufficient to inhibit platelet thromboxane production, and doses lower than those suggested for IG administration may be adequate.     

INTERNATIONAL EXCHANGE OF HERBAGE SEEDS AND THE O.E.C.D. HERBAGE SEED SCHEME

The use of the correct variety has an important influence on the economic use of sown grassland. The production of seed must be done in such a way that the essential characters of varieties are preserved. The O.E.C.D. Herbage Seed Scheme provides a sound basis for seed production, and has made possible the wider exploitation of good seed growing areas. The technical basis for some of the rules is discussed. It is concluded that in the 8 years in which the Scheme has been operating there has been a significant change in the pattern of seed use with a greater emphasis on the better varieties.     

THE EFFECT OF INTRAVENOUS INFUSIONS OF METHIONINE ON THE VOLUNTARY INTAKE OF GRASS SILAGE BY SHEEP

The effect of intravenous supplements of L-methionine on the voluntary intake of a ryegrass silage, prepared using formic acid as an additive, was determined in a 4×4 Latin Square experiment with 4 sheep. Animals receiving no methionine consumed 1061 g DM/day; those receiving 0.8, 1.2 and 2.0 g methionine/day consumed 1015, 1012 and 1078 g DM/day. The concentration of methionine in blood plasma (Y; (_imoles/I) increased with the dose rate of methionine infused (X; g/day) such that Y=36.7 + 38.3X (r=0.80; P<0.001). It is concluded that with a diet of this type methionine may be limiting for protein synthesis in the tissues but is not involved in the control of food intake.     

Aspects of forest restoration and hydrology:linking passive restoration and soil-water recovery in Brazilian Cerrado

Although the scientific knowledge about some associations between physical parameters of the soil is con-solidated,studies focused on investigating the dynamics...     

Field survey of rodents for Hepatozoon infections in an endemic focus of American canine hepatozoonosis

Eighteen of 31 (58%) cotton rats (Sigmodon hispidus) and 8 of 24 (33.3%) white-footed mice (Peromyscus leucopus) that were wild-trapped from 4 American canine hepatozoonosis endemic sites in Oklahoma were infected with Hepatozoon species. The predilection organ for merogony of the Hepatozoon species in cotton rats was the liver. Meronts were not detected in any of the white-footed mice. A 488 bp DNA fragment that includes a variable region of the 18S rRNA Hepatozoon gene amplified from blood or tissue of these infected animals. Sequences from eight cotton rats were 100% identical to each other as were sequences from three white-footed mice 100% identical to each other. The cotton rat sequence and the white-footed mouse sequence were 98.8% identical, differing in 6 bp of the 488 bp fragment. The DNA sequence from cotton rats was 97.7% identical to a Hepatozoon sp. described in a large bandicoot rat from Thailand and 97.5% identical to a Hepatozoon sp. in a bank vole from Brazil. The sequence from white-footed mice was 98.6% identical to the bandicoot rat sequence and 98.4% identical to the bank vole sequence. However, the sequences were only 90.6% (cotton rat) and 91.4% (white-footed mouse) identical to H. americanum. These findings suggest that the rodents are obligate intermediate hosts for distinct Hepatozoon spp., but not H. americanum.