PubMed Health⌕ Search

Biomedical subjects

R Halliday

Publications and source records attributed to R Halliday.

34 records · Page 2Linked to original sources
PubMed1978

Variation in immunoglobulin transfer from ewes to lambs.

The IgG1 concentrations in two-day-old lambs were significantly correlated with litter size, date of lambing, length of gestation and age of the dam. When these and other effects were allowed for significant breed differences were found, the concentrations being relatively high in Finnish Landrace, Welsh Mountain and Soay lambs, and relatively low in Border Leicester, Oxford Down and Southdown lambs. The concentrations in crossbred lambs were related to those in the parent breeds. The effects of the various factors on the yields of colostrum and total IgG1 by ewes were similar to their effects on the lamb serum concentrations. The yields were highly correlated with milk production. The heritabilities for IgG1 concentration in lambs and for total IgG1 production by ewes were estimated at 0.10 and 0.45, respectively.

Animals↗
PubMed1978

Immunoglobulin concentrations in Scottish Blackface lambs on a hill farm.

The serum immunoglobulin concentration in one- to 11-day-old Scottish Blackface lambs born outdoors on a hill farm were very similar to those in Scottish Blackface lambs born indoors on an experimental lowland farm. The concentrations were significantly higher in single lambs than in twins, and in lambs which survived for six months than in lambs which died, and showed significant annual variations which could not be related to the weather. They were significantly correlated with the ages of the dams, the lambs' gains in weight to weaning, but not with the weights or ratios of weights of the lambs and ewes after lambing, nor with the birth-coat types of sexes of the lambs. There were wide variations in the capacities of the abomasums at birth.

Animals↗
PubMed1978

The role of colostrum antibodies and the significance of antigenic competition in young lambs.

Young lambs were fed with a small amount of pooled colostrum and injected at either 1, 3, 6 or 12 weeks after birth with the antigen hen egg albumin (Ea). Five days before the Ea injection the experimental group were given a large dose of pooled vaccines (competing antigens). Blood samples were collected at regular intervals after the Ea injection. The results showed marked antigenic competition of Ea at both 6--and 12--weeks of age but the results were partially confounded by the presence of unexpected passive antibodies to Ea in the pooled fed. The experiment was repeated with a separate group of conventionally reared lambs given the same competing antigens but using human serum albumin (HSA) as the suppressed antigen. In this experiment the results differed since antibody concentrations and avidities to HSA were similar in 1, 6 and 12-week-old animals and there was no evidence for antigenic competition. The data presented illustrate the difficulties both of measuring immune responses in young ruminants and also of interpreting such results.

Animals↗
PubMed1976

Variations in immunoglobulin concentrations in Finnish x Dorset Horn lambs.

The serum immunoglobulin concentrations in two-day-old Finnish x Dorset Horn lambs, which were born and nursed indoors, were high and unrelated to littersize, except when young ewes had large litters, or when ewes lambed twice in a year. The results contrast sharply with those from Merino and Blackface lambs, examined previously, whose mean concentrations were much lower, and generally fell substantially with increasing litter-size. The superiority of the Finnish x Dorset Horn sheep in this respect is attributed to the ability of the lambs to suck particularly vigorously, shortly after birth, especially when large litters are compared, and to a higher rate of colostrum production by the ewes. The correlations between the immunoglobulin concentrations in the lambs and their growth and survival were significant but slight.

Age Factors↗
PubMed1976

Passive immunity in the lamb. Effects of a second feed of colostrum on antibody absorption from the first feed.

Lambs were taken from their mothers before sucking and fed pooled colostrum (30 g/kg body weight), containing added antibody to egg albumin, 1 h after birth. At 4 h after feeding there was a two-fold range in immunoglobulin (IgG) concentration and a sixteen-fold range in anti-egg albumin activity in their sera. The coefficient of correlation between the IgG and antibody concentrations was significant but low (r = 0.445, P less than 0.02). When a second feed of colostrum without added antibody was given 6 h after the first, both the IgG and the antibody concentrations increased significantly, indicating that there had been increased absorption from the first feed, rather than absorption from the second. The increases in IgG had a significant negative correlation with the IgG concentrations before the second feed (r = 0.760, P less than 0.001). Sera from control lambs fed only untreated colostrum gave only trace, probably non-specific, antibody reactions. The results suggest that single feeds of colostrum are generally inefficient, and that the passive immune status of young lambs may be improved and made more uniform by subsequent feeds, even though these may be themselves deficient in IgG.

Animals↗
PubMedDate not supplied

The effects of mild diastolic hypertension on the results of tests of cognitive function in adults 22 to 59 years of age.

OBJECTIVE: To test the hypothesis that mild diastolic hypertension (90 to 104 mm Hg) may induce asymptomatic impairment of cognitive function. DESIGN: Cross-sectional. SETTING: Community participants recruited to a university-based ambulatory care center. PARTICIPANTS: Three hundred twelve men and women with untreated essential hypertension and 47 normotensive subjects, 22 to 59 years of age. MEASUREMENTS AND MAIN RESULTS: Cognitive function tests measured reaction time to and accuracy in interpreting predetermined visual stimuli, the ability to acquire, reproduce, and change a set of arbitrary stimulus-response associations, and memory and learning of verbal information. These tests were selected to detect subtle differences in performances as opposed to differentiating neurologically normal persons from brain-damaged persons. After controlling for age, gender, and education, results showed that there was no significant difference between the normotensive and hypertensive subjects in two measures of reaction time to and four measures of accuracy in interpreting predetermined visual stimuli, in the measure of arbitrary stimulus-response associations, or in seven memory and learning variables. Although confidence intervals for the differences between means were wide, clinically significant differences were not likely to be present. Younger age was associated with faster reaction times, fewer errors, and better performance on memory and learning tasks, independent of diastolic blood pressure. CONCLUSIONS: The few detectable effects of untreated mild hypertension on cognitive function reported in the literature may be due to chance and are of questionable clinical significance.

Adult↗