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Biomedical subjects

L L Christian

Publications and source records attributed to L L Christian.

At least 37 records · Page 2Linked to original sources
PubMed1987

Genetic control of immune response to pseudorabies and atrophic rhinitis vaccines: I. Heterosis, general combining ability and relationship to growth and backfat.

Data from 988 pigs from 119 litters farrowed in two seasons of a three-breed diallel crossbreeding experiment were analyzed to estimate general combining abilities of breeds and heterosis for humoral immune response to pseudorabies virus and atrophic rhinitis vaccines. Twenty purebred boars and 85 sows of the Duroc, Landrace and Yorkshire breeds were mated to provide the nine breed-of-sire and breed-of-dam combinations. Immune response was measured after vaccination. A modified-live pseudorabies virus (PR) vaccine was administered to piglets at 28 d of age and response measured as log2 serum neutralization titers at 56 d. An inactivated B. bronchiseptica bacterin was administered at 28, 42 and 112 d. Antibody levels were measured relative to positive and negative controls at 28, 56 and 119 d by using an enzyme-linked immunosorbent assay. The results of this study showed that ranking by breed of sire and breed of dam did not differ for general combining ability, and no evidence of significant heterosis for any immune responses was observed. Higher immune response at 56 d to B. bronchiseptica vaccine was associated with lower weaning weight (r = -.09, P less than .01). Correlations of days to 100 kg with 56-d and 119-d B. bronchiseptica antibody levels were .15 (P less than .01) and .12 (P less than .01). The relationship between humoral immune response to PR vaccine and growth traits was similar to that observed for B. bronchiseptica vaccine. Immune response to both antigens was not associated with backfat thickness.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1987

Genetic control of immune response to pseudorabies and atrophic rhinitis vaccines: II. Comparison of additive direct and maternal genetic effects.

Data from 52 litters farrowed in two seasons of a cross-fostering experiment were analyzed to estimate variances and covariances for additive direct and maternal genetic effects on immune response to pseudorabies virus and B. bronchiseptica vaccine. Twenty purebred boars and 44 sows of the Duroc, Landrace and Yorkshire breeds were used. Immune response was measured after vaccine challenge. A modified-live pseudorabies (PR) vaccine was administered to piglets at 28 d of age; response was measured by log2 serum neutralization titers at 56 d. An inactivated B. bronchiseptica bacterin was administered at 28, 42 and 112 d. Antibody levels were measured relative to positive and negative controls at 28, 56 and 119 d by using an enzyme-linked immunosorbent assay (ELISA). Results from this study for heritability were .18 +/- .09 for PR titer and .15 +/- .07 and .52 +/- .15 for 56- and 119-d ELISA values, respectively. The variability due to nurse environment (maternal genetic variance and common environmental variance) as a percentage of phenotypic variance was 11.1% for PR titers and 29.6 and 8.8% for 56- and 119-d ELISA values, respectively. The heritabilities estimated in this study indicate that, if improved immune response to vaccines is desired, selection may be useful. However, the importance of maternal environment would make early selections less accurate than selections based on immune response measured later in life.

Animals↗
PubMed1987

Relationship between Mycoplasma hyosynoviae infection and front limb weakness in Duroc swine.

A relationship between degree of Mycoplasma hyosynoviae infection and front limb soundness was examined in 254 Duroc swine. These pigs represented 3 lines of pigs (structurally sound, control, and unsound) from a population divergently selected for 4 generations for front limb soundness. Analysis of sera collected every 4 weeks between 6 and 26 weeks of age yielded complement-fixing antibody titers that were believed to be indicative of the degree of natural infection with M hyosynoviae. Analysis of several variables defined by using titer values failed to reveal significant differences among the 3 selected lines, but trends indicated higher mean and peak titer values for pigs from the unsound line. Correlations between titer variables and front limb soundness variables within genetic groups were low and not significantly different from zero. Correlations between all titer variables were calculated; the correlation between mean titer and peak titer was 0.81 (P less than 0.01), and between mean titer and age at detection of first titer, was -0.56 (P less than 0.01). Pooled heritability estimates were 0.51 +/- 0.28 for mean titer and 0.28 +/- 0.25 for peak titer.

Animals↗
PubMed1985

Breed differences in return to estrus after PGF2 alpha-induced abortions in swine.

Fifty-seven Duroc, 41 Landrace and 38 Yorkshire purebred sows in d 10 to 53 of pregnancy were aborted to synchronize estrus by using prostaglandin F2 alpha (PGF2 alpha). Breed differences in time between injection of two 10-mg doses of PGF2 alpha and return to estrus were observed in these three breeds of pregnant sows during two breeding seasons. Duroc sows returned to estrus .9 d faster (P less than .01) than Yorkshire and 1.3 d faster (P less than .01) than Landrace sows. Seasonal differences were also observed. The mean days from injection to estrus were 1.8 d fewer (P less than .01) for the spring season than in the fall season. All sows expressed estrus 5 to 11 d after injection. Normal gestation, parturition and piglet survival were observed in the sows after the treatment. Genetic differences in response to induced abortion and return to estrus could have implications in planned breeding and farrowing systems.

Abortifacient Agents↗
PubMed1985

Effects of L-dopa supplementation on concentrations of brain catechols, dopamine receptor binding and the incidence of pale, soft and exudative meat in stress-susceptible pigs.

The purpose of this research was to determine if chronic dietary L-DOPA supplementation will alter differentially the brain catechol concentrations, dopamine receptor binding (KD and Bmax) and the incidence of pale, soft and exudative (PSE) meat in stress-susceptible (SS) and stress-resistant (SR) pigs. Stress-susceptible and SR pigs were assigned randomly to these four groups: SS pigs as controls, SR pigs as controls, SS pigs with L-DOPA supplementation and SR pigs with L-DOPA supplementation. The experiment began when pigs weighed 23 kg and terminated when pigs weighed 95 kg. Anatomical brain structures removed at slaughter included hypothalamus, thalamus, cortex, cerebellum, olfactory bulb, caudate nucleus, putamen and substantia nigra. Concentrations of norepinephrine and dopamine were greater in the hypothalami of SS than of SR control pigs. The L-DOPA supplementation eliminated the strain differences of brain catecholamine concentrations. Pigs fed L-DOPA had greater concentrations of dihydroxyphenylacetic acid in six of the eight brain regions analyzed than the controls. Dopamine receptor binding (Bmax and KD) of spiroperidol was similar in all four groups of pigs. Pale, soft and exudative pork developed to the same extent in SS pigs with or without L-DOPA treatment. The results suggest that L-DOPA supplementation eliminates strain differences in brain catecholamine concentrations but does not alter PSE meat development or striatal dopamine receptor binding.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1984

Age- and genotype-dependent differences in catecholamine concentrations in the porcine caudate nucleus.

Catecholamine concentrations of the caudate nucleus were determined by radioenzymatic assay in stress-susceptible and stress-resistant pigs at five different ages. Dopamine concentrations increased with age up to the time of puberty and declined thereafter in both genotypes of pigs. Generally, epinephrine concentrations increased with increasing age in both genotypes of pigs. Norepinephrine concentrations remained relatively constant for all ages of pigs except the oldest pigs. For most age groups, dopamine concentrations were lower in pigs of stress-susceptible genotype than in stress-resistant genotype.

Aging↗
PubMed1984

Breed and swine lymphocyte antigen haplotype differences in agglutination titers following vaccination with B. bronchiseptica.

Genetic differences in immune response to B. bronchiseptica after vaccination with a commercial B. bronchiseptica bacterin were investigated in 1,069 8-wk-old pigs. These pigs were from 65 litters born in the spring and 66 litters born in the fall of 1982 and were purebreds from the Chester White (n = 128), Duroc (n = 281), Hampshire (n = 143), Landrace (n = 309) and Yorkshire (n = 208) breeds. Each litter was raised separately. Individual pigs were vaccinated im at 4 and 6 wk of age with 2 ml of B. bronchiseptica bacterin. At 8 wk of age, 8 ml of blood were collected from each animal and serum prepared to determine agglutinating antibody titers against B. bronchiseptica bacterin by a bacterial agglutination method. In addition, lymphocytes were separated from 1 ml of heparinized blood and used to determine Swine Lymphocyte Antigen (SLA) haplotypes by using cytotoxic antibodies against the SLA complex. Antisera for 3 SLA haplotypes were made available by the National Institutes of Health. Results indicated that breed of pig (P less than .01) and dam of pig (P less than .01) affected the immune response of the pig after B. bronchiseptica vaccination. Higher immune response was also associated (P less than .05) with one of the SLA haplotypes tested. Heritability estimates for immune response following vaccination were .10 +/- .12 (half-sib) and .42 +/- .19 (full-sib). Results suggest that the relationship of the SLA complex to immune response in the pig and nonadditive genetic and maternal effects on immune response should be further investigated.

Agglutination Tests↗
PubMed1984

Genetic differences in serum-neutralization titers of pigs after vaccination with pseudorabies modified live-virus vaccine.

Four-week-old pigs of the Chester White, Duroc, Hampshire, Landrace, and Yorkshire breeds (n = 518) were vaccinated with a pseudorabies modified live-virus vaccine to determine whether genetic differences existed for immune response after vaccination. All pigs and their dams (sows) were tested before vaccination to determine preimmunization antibody titers, using a microtitration serum-neutralization (SN) test. The SN test results of sows were negative, as were preimmunization tests of the pigs. At 4 weeks after pigs were vaccinated, additional blood samples were collected from the pigs, and end-point SN titers were determined, using a 2-fold dilution scheme. Small, but statistically significant, breed differences existed for antibody response, with Yorkshire and Chester White pigs having the highest response, and Duroc and Landrace pigs, the lowest. Differences among sire progeny groups were small, but there were significant differences among dams. Genetic differences as seen by differences among breeds indicates that the efficacy of vaccines may vary from breed to breed and that vaccine trials should not neglect this potential source of variation.

Animals↗
PubMed1983

Genetic variability at the pig SLA complex in U.S. breeds of pigs.

Lymphocytes from 90 mature pigs and 548 growing pigs from 65 litters were screened with cytotoxic antibodies against swine lymphocyte antigens. Pigs included in the survey were from the Chester White, Duroc, Hampshire, Landrace and Yorkshire breeds. Significant differences between breeds were found in the frequency of the three haplotypes tested. Such differences may provide the genetic variability needed to determine associations between disease susceptibility and the pig's major histocompatibility gene complex.

Animals↗
PubMed1981

Blood lactate kinetics in normal and stress-susceptible pigs.

In vitro rates of lactate metabolism were determined in stress-susceptible (SS) and stress-resistant (SR) pigs. Three SR and three SS pigs were given 20 muCi of [U-14C] L-lactate by a single injection method and resting blood lactate kinetics were measured. Seventeen blood samples were taken during the 60 min after injection. Lactate was separated from the deproteinized plasma by silicic acid column chromatography, and specific radioactivity was determined. Kinetic characteristics were calculated from plots of specific activity versus time. Pigs met steady-state requirements during the sampling period. There were no differences in kinetic characteristics of resting SS and SR pigs. Later, a second isotope injection was given after 5 min of electrical stress. Lactate pool sizes increased similarly in both types of pigs after stress; however, SS pigs had greater plasma lactate concentrations after stress. It is concluded that SS and SR pigs respond differently to stress but have similar capacities to metabolize lactate while resting.

Animals↗
PubMed1980

Halothane sensitivity and linkage of genes for H red blood cell antigens, phosphohexose isomerase (PHI) and 6-phosphogluconate dehydrogenase (6-PGD) variants in pigs.

Data from matings appropriate to test linkage in pigs of genes for halothane sensitivity (HAL), H red cell antigens, phosphohexose isomerase (PHI) and 6-phosphogluconate dehydrogenase (6-PGD) red cell isoenzyme variants were consistent with a gene order of Phi-Hal-H-Pgd. There was no unequivocal evidence for a Hal locus separate from Phi, although the phenotype of one pig not tested for halothane sensitivity suggested recombination between Hal and Phi. Breeding tests confirmed that in two cases there had been recombination between Hal and H. Offspring of one of these recombinant types provided evidence for a locus for a gene for inhibition of expression of A and O separate from the locus for H.

Animals↗
PubMed1980

Influence of caffeine on blood creatine phosphokinase levels in swine.

Eight stress-susceptible and eight normal pigs weighing 35 to 50 kg were studied to determine if caffeine administration would trigger the stress syndrome and affect blood CPK levels. The pigs were littermates of Yorkshire descent. One gram of caffeine (dissolved in 10 ml of saline-sodium benzoate solution) was infused into the pigs through a jugular catheter at a rate of 1.0 ml/min. Blood samples were collected through the catheter before caffeine administration and at specific intervals up to 8 hr after the caffeine administration for the determination of blood creatine phosphokinase levels. The pigs were sacrificed approximately 48 hr after caffeine administration, and M. longissimus pH and reflectance values were obtained 45 min and 24 hr postmortem. Caffeine administration stimulated the development of the signs associated with the porcine stress syndrome in seven of the eight pigs genetically classified as stress-susceptible, and only one control pig exhibited an early sign of the stress syndrome, muscle tremors. Blood CPK levels did not differ significantly between the normal and stress-susceptible groups until visual signs of the stress syndrome were no longer observed (approximately 45 min after caffeine administration). Stress-susceptible pigs had significantly higher blood CPK levels than controls 45 min after the initial caffeine administration. Physical stress received by the pigs during transport and the stress from being held in a new environment resulted in a greater elevation of blood CPK than did the stress administered through the caffeine infusion.

Animals↗
PubMed1976

H blood types in pigs as predictors of stress susceptibility.

At least two genotypes in the H system of blood groups in pigs are responsible for blood types associated with the porcine stress syndrome (PSS), and at least three genotypes are responsible for blood types associated with freedom from PSS. Two blood types, each of which apparently may result from more than one genotype, are associated with PSS in some pigs and not in others.

ABO Blood-Group System↗
PubMed1976

Gluconeogenesis from lactate in liver of stress-susceptible and stress-resistant pigs.

In vitro rates of lactate conversion to glucose and oxidation to CO2 were determined in livers of stress-susceptible (SS) and stress-resistant (SR) pigs because we hypothesized that livers of SS pigs had a lower capacity than livers of SR pigs to remove lactate from blood. Stress-susceptibility was determined by reaction to halothane at 7 weeks of age. At approximately 9 weeks of age, pigs were assigned to one of three experimental diets. Pigs weighing 95 kg were slaughtered immediately after stress, and liver samples were obtained. Incorporation of lactate into glucose in liver of SS pigs was 38% of that in SR pigs. Addition of either vitamin C or vitamins C and E plus magnesium oxide and collagen extract to a corn-soy diet did not alter lactate conversion to glucose, but depressed lactate oxidation to CO2. No differences were detected in either activities of lactate dehydrogenase, HAD-malate dehydrogenase, phosphoenolpyruvate carboxykinase, fructose-1,6-diphosphatase, and glucose-6-phosphatase or concentration of glycogen in livers of SS and SR pigs. Our data indicate that livers of SS pigs possess a lower capacity to incorporate lactate into glucose and to oxidize lactate to CO2; maximal activities of enzymes measured in this study are not the cause of these differences. Reduced capacity of lactate metabolism in livers of SS pigs seems a part of the etiology of the porcine stress syndrome.

Animals↗