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Infectivity of Canadian isolates of Trichinella spiralis nativa for swine, rats and carnivores.

The infectivity of Trichinella spiralis nativa isolates from widely separated geographic areas of Canada was determined by feeding infected musculature to swine, laboratory rats and carnivores (cats, foxes, ferrets). Low infectivity for swine and rats and high infectivity for carnivores were observed. Light infections were established in four of 16 swine examined between 25 and 53 days postinfection. Feeding of infected porcine musculature to ferrets demonstrated that Trichinella spiralis nativa can be passaged through swine even though the infectivity rate is low.

Animals↗

In vitro studies of group E streptococci in swine leukocytes. 3. The migration inhibition test as an indication of delayed hypersensitivity in streptococcic lymphadenitis.

A procedure for conducting tests for leukocyte migration inhibition was developed for swine leukocytes. Leukocytes from normal swine were found to be inhibited by a factor of less than 20% in the presence of the whole cell antigen of group E Streptococci (GES). However, the migration of leukocytes from swine which had been exposed to GES was inhibited by more than 60% in the presence of the antigen. This was considered as significant and an indication for the presence of delayed hypersensitivity to GES in previously exposed swine.

Animals↗

Adaptation of Sinclair swine melanoma cells to long-term growth in vitro.

Sinclair swine melanoma usually regresses in vivo. In the present study, swine melanoma cells were adapted to long-term growth in culture. The morphology of cultured melanoma cells ranged from dendritic to cuboidal, similar to that described for human melanoma cells. Doubling times of the swine melanoma cells were also similar to those of human melanoma cells in vitro. 3,4-Dihydroxy-L-phenylalanine oxidase-positive cells were detected by light microscopy, and melanin and premelanosomes were detected by electron microscopy. Cell cultures could be propagated from progressing, partially regressed, and primary cutaneous lesions, as well as from visceral metastases. Thus, it appears that, under these cell culture conditions, Sinclair swine melanoma cells can be adapted to prolonged growth in vitro.

Animals↗

Cholesterol turnover, synthesis, and retention in hypercholesterolemic growing swine.

Studies of the interaction of cholesterol absorption, excretion, synthesis, and retention were carried out with growing swine through the application of sterol and isotopic balance procedures to a non-steady state situation. The animals were fed either a low-fat commercial mash diet (MA), a commercial mash diet plus 2.4 g/day of crystalline cholesterol (MAC), or a high-fat milk diet containing 2.4 g/day cholesterol (MKC). [(14)C]Cholesterol and beta-[(3)H]sitosterol were used to measure fecal neutral steroid losses. Final plasma cholesterol levels averaged 91, 85, and 195 mg/100 ml for MA, MAC, and MKC animals, respectively. Total carcass dissection followed by cholesterol measurement revealed that accumulation of cholesterol in most body tissues was directly related to increase in body size in the rapidly growing swine. The only notable exceptions were plasma, liver, and bone with marrow of the MKC group, where cholesterol concentrations were significantly elevated. Absorption of cholesterol was significantly greater in animals fed MKC than MAC-fed swine (726 mg/day vs. 142 mg/day), whereas synthesis of cholesterol was significantly greater in MAC animals than in MKC animals (863 mg/day vs. 112 mg/day). Excretion of neutral and acid steroids into the intestine was not significantly different between MAC and MKC groups, but both classes of steroids were more efficiently reabsorbed in MKC animals. The overall differences between swine fed mash-cholesterol and those fed milk-cholesterol diets appear to result from more efficient absorption of both neutral and acid steroids in the milk-cholesterol group only partially compensated for by decreased cholesterol synthesis.

Animals↗

[Species specificity study of swine leukocyte interferon on different cell cultures].

The antiviral effect of swine leukocyte interferon was studied in cell cultures of different origins. Swine leukocyte interferon was demonstrated to protect human diploid fibroblasts. The cultures of primarily trypsinized mouse embryo fibroblasts and continuous bovine embryo tracheal cells are as sensitive to swine leukocyte interferon as human diploid cells. Studies of the age sensitivity of mouse fibroblast tissues to swine interferon showed the tissue sensitivity to interferon to decline markedly with age.

Animals↗

Principles of a full 'relay toxicity' experiment and results conducted with carbadox, a feed additive used as growth promoter for growing swine.

Relay toxicity is a new approach which permits an evaluation of the harmlessness of residues found in tissue, for the human consumer. Farm animals, swine for example, received high quantities of the additive over a long period. The swine were sacrificed without any withdrawal. Their meat and liver were added to the feed ration of laboratory animals to study the eventual problems of residue and metabolites. The following experiments were performed using carbadox:--Levels of carbadox up to 200 ppm were added to the swine ration (a maximum of 20 ppm is authorized). The meat and dehydrated liver were given in doses of 20% and 10% respectively, in the rat feed for 2 years or 3 generations.--The fresh meat, frozen then thawed at the time of use, was distributed to dogs daily for 7 1/2 years. No abnormalities were found, either in the growth of the animals or in their descendants. No abnormalities were observed macroscopically or microscopically after sacrifice. Relay toxicity gives high coefficients of security when the additive is used without withdrawal up to the time of sacrifice. This study demonstrated that the use of carbadox in swine doesn't present any disadvantage to the human consumer.

Animals↗

Apolipoprotein B accumulation and development of foam cell lesions in coronary arteries of hypercholesterolemic swine.

We wished to determine whether plasma low density lipoproteins (LDL) preferentially accumulate at specific anatomical sites in swine coronary arteries that are predisposed to atherosclerotic lesion development, and if so, to determine what alteration in wall structure may be responsible for this accumulation. Therefore, we measured the accumulation of apolipoprotein B (apo B), the major protein in LDL, by electroimmunoassay in seven separate segments of coronary arteries from swine fed a hypercholesterolemic or normolipemic control diet for periods of 4 to 15 weeks. Apo B accumulation was greater in segments from swine fed a hypercholesterolemic diet than in segments for corresponding time intervals from swine fed a normolipemic diet and was greater in proximal than in distal segments (nonbranch points) of coronary arteries. This accumulation of apo B generally increased with time on the hypercholesterolemic diet, already appearing elevated relative to controls at 4 weeks on the hypercholesterolemic diet, whereas the initial appearance of foam cells in these regions occurred at 6 weeks. Apo B was localized by immunofluorescence almost exclusively to areas of diffuse intimal thickening in the proximal portions of the coronary arteries and to focal areas of intimal thickening or cushions at branch points in more distal segments. In these regions, apo B was found primarily in edematous, cell-sparse zones close to the lumen surface, rather than the smooth muscle cell-rich areas making up most of the thickened intima. Apo B in these areas was associated with Alcian blue-positive areas suggested to contain sulfated glycosaminoglycans, which may be responsible for the preferential LDL accumulation. The diffuse and focal intimal thickening does not appear to have been induced by the hypercholesterolemia or the subsequent deposition of LDL, since such thickening was found at the same sites and to about the same degree in the normolipemic control animals. Thus, this study has shown that the areas of earliest and preferential accumulation of LDL are sites of intimal thickening containing deposits of sulfated glycosaminoglycan, and that these are the regions at which the first foam cell lesions eventually appear. These findings add additional strong circumstantial data linking LDL deposition in arteries to the atherosclerotic process.

Animals↗

Evidence for transformation of sulfamethazine to its N4-glucopyranosyl derivative in swine liver during frozen storage.

An analytical procedure for determining N4-glucopyranosylsulfamethazine (GPS) in swine livers is described. The sulfamethazine derivative is extracted from the tissues with water. GPS is isolated in sufficient purity for liquid chromatographic determination by a series of adsorption chromatographic procedures. Recovery of the conjugate from spiked swine livers was 82.2% with a coefficient of variation of 4.5%. Evidence is presented suggesting that sulfamethazine in swine livers is transformed to GPS during frozen storage. Two samples of swine liver in which incurred sulfamethazine residues were substantially depleted during frozen storage were analyzed for GPS. The conjugate accounted for 96.2% and 92.2% of the depleted sulfamethazine residues.

Animals↗

Evans blue dye. Accumulation in swine aortic intimal cell collections and atherosclerotic lesions.

A two-part study concerned the accumulation of intravenously injected Evans blue dye in the abdominal aorta of swine. In normolipidemic swine weighing up to 90 kg each, Evans blue accumulated predominantly in areas of the aorta that were the site of intimal smooth muscle cell collections. The second part of the study dealt with Evans blue accumulation in swine with advanced atherosclerosis. The extent of blue staining in these animals was not significantly different than in normolipidemic, nonatherosclerotic swine of the same size. The dye showed a predilection for raised atherosclerotic lesions, but only one quarter of the surface of these lesions was stained. Histologic studies of the uppermost portion of blue and nonblue lesion areas showed that the dye preferentially accumulated in regions with lower concentrations of foam cells. Injected isotopic cholesterol tended to accumulate in the blue rather than the nonblue areas.

Animals↗

A single radial hemolysis technique for the measurement of influenza virus antibody in swine serum.

A single radial hemolysis technique was applied to the measurement of swine influenza virus antibody in swine serum. It was recognized to be useful for the detection of this antibody, although heating at 56 degrees C for 30 minutes was necessary to remove non--specific hemolysis from the test sample. The single radial hemolysis titer was correlative with the hemagglutination--inhibition titer in serum from pigs infected experimentally or naturally. This technique is simple, rapid and unaffected with non--specific inhibitors in swine serum. It does not require concentrated purified virus either. Therefore, it is applicable to the sero--epizootiologic surveillance of swine influenza on a large scale.

Animals↗

Five putative subclasses of swine IgG identified from the cDNA sequences of a single animal.

We report the sequences of more than 40 partial and complete swine C gamma cDNAs obtained by PCR cloning of first strand cDNA, and from a cDNA expression library, all from a single animal. These seem to represent five IgG subclasses, that can be grouped into two clusters; one contains IgG1 and IgG3 and the other, IgG2a, IgG2b and IgG4. IgG2a and IgG2b differ by only three amino acids, but single strand conformational polymorphism analyses of PCR-amplified IgG2-specific segments in animals of different breeds, argues for their putative subclass status. Major subclass differences are found in the hinge and C gamma 3, but differences in upper hinge length, associated with segmental flexibility in the IgGs of other species, are absent. All subclasses have identical middle hinge segments that can accommodate three interheavy chain disulfide bridges. The putative swine IgG subclasses have their greatest similarity with those of the human except for the near absence of hinge region variation. Swine subclasses such as ruminant IgG2a, have a lower hinge deletion which in human IgG1, contains one of the motifs believed necessary for interaction with Fc gamma Rs. IgG1 was the most frequently encountered subclass cDNA (25 of 43) and the single swine-mouse hybridoma tested had a sequence identical to IgG1. Partial sequence analyses of genomic clones identified one clone identical with the IgG1/IgG3 subclass cluster, two identical to the IgG2b/IgG4 subclass group, and two identical to each other but different from any of the expressed sequences reported here. Genomic blots suggest that up to eight C gamma genes are present in the genome.

Animals↗

Effect of magnesium sulphate infusion on ex vivo platelet aggregation in swine.

The effect of magnesium sulphate infusion on ex vivo platelet aggregation in 11 female Yorkshire swine was observed using platelet-rich plasma and different agonists (ADP 5 mM; ADP 10 mM and collagen 1 mg/ml). Infusion of 1 g MgSO4 over 1 h produced a significant decrease in platelet aggregability. A dose-dependent effect of different ADP concentrations on platelet aggregation was noticed. Platelet inhibition was most consistent when using ADP 5 mM. We estimate this concentration of agonist as optimal in swine. The swine model is a good choice for investigation of in vivo platelet activation, especially with regard to cardiovascular research. We conclude that there is an inhibitory effect of supplemental magnesium on ex vivo platelet aggregation in swine with initial normomagnesaemia.

Adenosine Diphosphate↗

Prevalence and types of birth defects in Ontario swine determined by mail survey.

Preweaning mortality in piglets constitutes a major loss to the swine industry. Congenital defects account for a small but significant proportion of these losses. To implement appropriate strategies to reduce such losses, it is necessary to identify the specific causes and their relative importance. Consequently, a mail survey of swine production in Ontario was carried out to determine the prevalence and types of birth defects. Statistical comparisons of the prevalence of overall defects were made between accurate and estimate records, breeds (cross vs. purebred), size of operation (number of sows) and geographic location. The mean litter size of 11 pigs born per sow was not significantly different for those with accurate versus estimate records, but the difference in the prevalence of defective pigs (live and dead) was significant (accurate 3.1% vs. estimate 4.1%). Splayleg (spraddleleg) was the most common defect. The next four defects for both groups were belly rupture, other rupture, ridglings and other, but not in the same ranking. Purebred and small farm operations (< 25 sows) had a significantly higher prevalence of birth defects for estimated data only. Geographic location had no effect. Further work is required to determine whether recording prevalence of birth defects in Ontario swine will provide a useful monitor of environmental stress. The study provides a baseline for the prevalence and type of defects in Ontario swine.

Animal Husbandry↗

Evaluation of a rapid method of determination of plasma fibrinogen in swine.

An evaluation was made of a rapid semiautomated method for determining fibrinogen level in swine plasma. This method, referred to as thrombin time method or fibrometer method, is based on the principle that when thrombin is added to suitably diluted plasma, the time of clotting is linearly related to the fibrinogen concentration. The linear regression model for the standard curve prepared using swine plasma had an r value of 0.998. A comparison between the fibrometer and the Grannis methods done on 189 swine plasma samples showed good correlation between these two mehtods (r value 0.847). It was concluded that although the fibrometer method may not be as precise as the Grannis method, it would still be acceptable for clinical use in swine.

Animals↗

Mutagenicity of stable dust and drinking water on swine and cattle farms.

Single pilot examinations of mutagenicity of stable dust and drinking water were made on three swine farms (D., M., T.) and one cattle farm (N.) in the district of Hodonín in summer 1994. The mutagenicity was examined by the Ames test using the indicator strains Salmonella typhimurium TA 98 and TA 100 with (+S9) or without (-S9) metabolic activation. At the same time the contents of selected pesticides (PES) and polychlorinated biphenyls (PCB) in stable dust and drinking water and that of polycyclic aromatic hydrocarbons in stable dust were determined. Increased mutagenicity was demonstrated in drinking water (strain TA 98 with metabolic activation; index Rt/Rk 3.6-7.7) and stable dust (strain TA 100 with metabolic activation; index Rt/Rk 2.2) collected on the swine farm M. High contents of PAH (8.246 mg/kg) and PCB (0.263 mg/kg) were also found in the dust samples collected on this farm. Only drinking water showed mutagenic activity (strain TA 98 without metabolic activation; index Rt/Rk 2.6) on the swine farm D. On both the farms, the number of revertants was dose-dependent. Increased content of PAH (2.553 mg/kg) was also demonstrated on the dust samples collected on the farm D. No significant increase (twofold or higher when compared with negative controls) of mutagenic activity of stable dust or drinking water was demonstrable on the swine farm T. and the cattle farm N. Substances responsible for the mutagenicity of drinking water on the farms D. and M. have not yet been identified. Anyway, the increase of mutagenicity of stable dust and drinking water should be taken as a warning that mutagens that can jeopardise animal and human health have penetrated into the stable environment.

Animals↗

Variable and constant regions in African swine fever virus DNA.

An analysis of the SalI restriction pattern of African swine fever virus DNA showed that the SalI recognition sites did not change after more than 100 virus passages in porcine macrophages. The virus strain BA71V, obtained from the virus isolate BA71 by adaptation to grow in VERO cells, differed from the nonadapted virus in two deletions with a length of 2.5 and 7 kb located close to the DNA ends. A restriction analysis of several virus clones obtained from a naturally infected pig revealed length heterogeneity in both variable regions. A comparison of SalI restriction maps from 23 African swine fever virus field isolates (8 African, 11 European, and 4 American) has shown that the virus genome consists of a central region with a constant length of about 125 kb and two variable regions located close to the DNA ends with a length of 38-47 kb for the left DNA end, and 13-16 kb for the right DNA end. The total length of ASF virus DNA varied between 178 (BA71) and 189 (MOZ64) kb. The 23 African swine fever virus isolates were classified into five groups, according to the arrangement of the SalI sites in the central region. Four groups contained only African isolates, whereas all the European and American isolates belonged to the same group. This distribution of isolates suggests that all non-African virus field isolates have a common origin.

Africa↗

Immunity to transmissible gastroenteritis virus and porcine respiratory coronavirus infections in swine.

Despite the pioneering efforts to identify correlates of passive immunity to transmissible gastroenteritis virus (TGEV), effective vaccines for the control of TGE in suckling pigs have remained elusive. The initial concept of an enteromammary immunologic axis in monogastrics originated from studies of lactogenic immunity to TGEV in swine. These studies revealed that infection of pregnant swine with virulent TGEV stimulated high titers of SIgA antibodies in milk which correlated with protection of suckling pigs against TGE; parenteral or oral inoculation with live attenuated or killed TGEV vaccines induced mainly IgG antibodies in milk which generally provided poor protection to suckling pigs. The recent appearance of PRCV infections in swine and continuing studies of TGEV infections, present a unique model for further studies of mucosal immunity. Research using these viruses has increased our understanding of the various components of the common mucosal immune system and their interactions. Although the most important consideration in designing an effective vaccine for TGEV is the stimulation of GALT through intestinal virus replication, studies addressing the contribution of BALT to immunity to TGEV and PRCV may provide insights for alternative vaccine approaches. The mechanism by which exposure to PRCV elicits a variable-degree of immunity to TGEV challenge is unknown. Virus replication in the gut or respiratory tract is a major factor affecting the magnitude of the immune response at the respective site and may be necessary for the recruitment of specific immune cells from other mucosal inductive sites, i.e., GALT to BALT and BALT to GALT migration.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗