Search PubMed⌕ Search

Biomedical subjects

F Jackson

Publications and source records attributed to F Jackson.

At least 91 records · Page 5Linked to original sources
PubMed1986

Computer assisted tomography of the apophyseal changes in patients with ankylosing spondylitis.

We have examined the appearances by computed tomography of the apophyseal joints in 28 patients with ankylosing spondylitis (AS), as well as in 10 patients with noninflammatory lumbar disease. The number of changes noted in the apophyseal joints in each patient correlated significantly with the degree of restriction of spinal flexion seen (p = 0.002), but did not correlate with the clinical duration of disease (p greater than 0.2). No specific abnormalities were seen in patients with AS that were not also noted in the non-AS subjects.

Adult↗
PubMed1986

Transfer of immunity to Ostertagia circumcincta and IgA memory between identical sheep by lymphocytes collected from gastric lymph.

Sheep rendered immune to Ostertagia circumcincta were challenged with 50,000 larvae and lymphocytes were collected from the gastric lymph up to eight days after challenge. The cells were transferred intravenously to genetically identical worm-free sheep which, together with controls, were challenged with 50,000 larvae and killed nine days later. Cells obtained during the donors lymphoblast response to challenge transferred partial immunity, measured either as stunting or loss of worms. Significantly less immunity was transferred by cells collected either before or after this response. Thus the responding cells can mediate protective immunity to O circumcincta. On the other hand the donor sheep remained immune to their challenge infection despite being depleted of these functional cells, showing that their presence was not essential for immunity to be maintained. Comparison of the immunoglobulin A (IgA) concentrations in the gastric lymph of recipient and control sheep showed that a local IgA response had also been transferred. Enumeration of mucosal mast cells suggested that a mastocytosis had been transferred to the two recipients which were most immune to challenge.

Animals↗
PubMed1985

Independent co-release of acetylcholine and somatostatin from cardiac vagal neurones in toad.

Vagal postganglionic neurones in toad (Bufo marinus) cause cardio-inhibition by releasing both acetylcholine and somatostatin. In isolated, electrically paced, toad atria, intracardiac neurones were stimulated by short bursts of high-voltage pulses applied during the atrial refractory period. Treatment with hemicholinium-3 (5 X 10(-4) M) for 5 h eliminated most of the acetylcholine-mediated cardio-inhibition but did not inhibit somatostatin-mediated transmission. It is concluded that somatostatin release does not depend on the simultaneous release of acetylcholine.

Acetylcholine↗
PubMed1985

Age immunity to Ostertagia circumcincta: comparison of the local immune responses of 4 1/2- and 10-month-old lambs.

In 2 experiments, the local immune response to infection with 50,000 O. circumcincta was monitored in 4 1/2-month-old previously infected lambs by following changes in the composition of gastric lymph. The previously infected lambs were partially resistant to the challenge in that they harboured a greater proportion of early fourth stage parasites and that the developing larvae recovered from them were distinctly shorter than those present in controls. They also exhibited a secondary local immune response in the gastric lymph consisting of increases in the output of lymphoblasts and IgA cells which peaked 3 to 5 days after challenge, followed by increases in lymph IgA and IgA anti-larval antibody on days 6 and 7. The size of the total IgA response in a sheep was highly correlated with the degree of stunting of its larvae, suggesting that IgA antibody can reduce the growth of developing Ostertagia. When compared with the results of 2 identically designed experiments carried out previously in 10-month-old sheep, the younger lambs were measurably less resistant to challenge and most aspects of the magnitude of the local immune response were significantly depressed, although the timing of the response was similar. It is suggested that this poorly developed ability to mount a secondary mucosal immune response may explain the relative failure of the younger lamb to develop resistance to gastro-intestinal nematodes.

Aging↗
PubMed1985

Effect of experimental Ostertagia circumcincta infection on the performance of grazing lambs.

Groups of 10 three-and-a-half-month-old Suffolkcross lambs were infected daily, five times a week, for 12 weeks with either zero, 500, 1500, 3000 or 5000 larvae of Ostertagia circumcincta and grazed together on a series of 'clean' paddocks. All the lambs were moved at seven to 10 day intervals to a fresh paddock to prevent autoinfection and were killed after 14 weeks. Another group was killed at the outset as a control for carcase analysis. Mean O circumcincta populations were 34 (grazing control) and 1224, 473, 1092 and 4331 for the groups receiving 500, 1500, 3000 and 5000 larvae per day respectively. The percentage of fourth stage larvae increased with increasing larval intake. Extensive abomasal damage with mucosal hypertrophy and depletion of parietal cells occurred in the lambs receiving 3000 and 5000 O circumcincta larvae per day. Intakes of 1500 larvae per day and above depressed growth rate by 24 to 37 per cent, reduced the deposition of protein in the carcase by 34 to 52 per cent and lowered calcium/phosphorus deposition by 23 to 48 per cent. Plasma pepsinogen concentrations were consistently elevated in lambs receiving 3000 or 5000 larvae per day and may be a useful aid to recognising abomasal damage sufficient to affect productivity.

Abomasum↗
PubMed1985

Effect of Ostertagia ostertagi on lamb performance and cross resistance to O circumcincta.

Fifteen worm-free lambs (two-and-a-half to three months or four to four-and-a-half months old) were infected with 3500 or 4000 Ostertagia ostertagi larvae on five days each week for six weeks, and their performance compared to that of controls. Eleven lambs were killed after eight weeks and four were challenged with O circumcincta to determine whether any cross resistance had developed. A feature of the O ostertagi infection was the considerable variation in response. Overall liveweight gain was lowered by 24 per cent in the two-and-a-half to three-month-old infected lambs, mainly due to reductions of 27 to 40 per cent in four of the seven lambs. There was no consistent effect in the older lambs. The worm populations consisted mainly of early fourth stage larvae and developing worms, but a small percentage reached sexual maturity and these produced a low faecal egg count (1 to 63 eggs per gram). Numerous intraluminal refractive crystals were present in the gut of both adult worms and developing stages, possibly reflecting degenerative changes. Hypertrophy of the abomasal mucosa with patchy loss of differentiation was a feature of the infection, and in four lambs serum pepsinogen concentrations were elevated. Exposure to O ostertagi did confer some protection against challenge with O circumcincta in that worm counts were reduced to about 60 per cent of those in controls, although no increase was observed in the numbers of arrested larvae. The successful passage of O ostertagi through young lambs could be important in mixed or alternate grazing systems by providing a reservoir of infection for the alternate host.

Animals↗
PubMed1984

When to spay.

Explore the source record for details and available documents.

Animals↗
PubMed1984

Manifestations of resistance to ovine ostertagiasis associated with immunological responses in the gastric lymph.

Groups of previously infected and worm-free sheep were serially killed up to 10 days after challenge with 50 000 Ostertagia circumcincta larvae. Two similar groups of sheep were killed 10 days after challenge with 1000 larvae. The previously infected sheep were resistant to the smaller challenge dose in that fewer, stunted worms were recovered from them than from controls. However, this resistance was not as marked as that observed in the previously infected sheep which received the large challenge, because proportionally fewer worms were recovered after the 50000 dose and the great majority of these were arrested at the early fourth stage. The gastric lymph ducts of 6 previously infected sheep were cannulated successfully and a marked local immune response was detected in 3 sheep which were challenged with 50 000 larvae. No response was detected in 3 cannulated sheep challenged with 1000 larvae. In the lymph of the 50 000 dose group, a temporary increase in pepsinogen activity suggested that a hypersensitivity reaction related to the presence of large numbers of mucosal mast cells began between 24 and 48 h after challenge. This was followed by marked increases in the cellular and IgA content of lymph, which reached peaks on days 3 and 6, respectively. It is suggested that the response detected in the gastric lymph reflected aspects of a local immune reaction in the abomasal mucosa and that this reaction accounted for the enhanced degree of resistance to the larger challenge dose.

Animals↗
PubMed1984

Comparison of saline incubation and pepsin digestion as methods for recovering Ostertagia circumcincta larvae from the abomasum of sheep.

Incubation in saline at 37 degrees C was compared with pepsin digestion as a quantitative method for recovering larval stages of Ostertagia circumcincta from the abomasal mucosa of sheep. Experiments showed that the techniques were of roughly similar efficiency even when the larvae were arrested but that the saline method was preferable because worm searching was easier and quicker.

Abomasum↗
PubMed1984

Further observations on faecal egg output in lambs dosed continuously with Ostertagia circumcincta.

The relationship between size of intake of infective larvae of Ostertagia circumcincta and faecal egg output by lambs was examined in two experiments in four-month-old Suffolk cross lambs dosed five times per week for 10 weeks. The first experiment compared two strains, Weybridge and Moredun, at two levels, 400 and 4000 per dose. The second experiment compared two levels, 40 and 400 per dose, of Moredun larvae. The group mean output of worm eggs was almost unaffected by the 10-fold reduction in intake from 4000 to 400. The further reduction from 400 to 40 reduced egg output by a factor of 2.5.

Animals↗
PubMed1984

Resistance to Haemonchus contortus transferred between genetically histocompatible sheep by immune lymphocytes.

The pattern of faecal egg counts after infection with 10,000 Haemonchus contortus larvae was similar within but not between, four pairs of monozygous twin sheep. Transfer of whole lymph or washed lymph cells from three immune donor sheep to their identical co-twin recipients reduced the susceptibility of the recipients to challenge with 10,000 larvae as measured by faecal egg counts. Cells from a nonimmune donor did not have this effect. In a final experiment, washed cells from an immune triplet sheep, which was actively responding to a repeated challenge infection, transferred a secondary local IgA response to a second recipient triplet and resulted in a marked reduction in worm count when compared with that of a third infectivity control triplet.

Animals↗
PubMed1983

False start.

Explore the source record for details and available documents.

Education, Nursing↗
PubMed1983

Studies on the local immune response of the lactating ewe infected with Ostertagia circumcincta.

Changes in the flow and composition of gastric lymph were monitored in groups of lactating and non-lactating ewes which were repeatedly infected with Ostertagia circumcincta. As judged by faecal egg counts and worm burdens the lactating group was more susceptible than the non-lactating controls to the challenge infection. Increased amounts of pepsinogen as well as larger numbers of eosinophils and neutrophils entering the gastric lymph indicated considerable abomasal damage and inflammation in the lactating ewes. However, measurement of the flow of lymphocytes as well as the amount of IgA and IgA antibody in the lymph did not indicate that these aspects of the local immune response were impaired during lactation; in fact the output of IgA-containing lymphocytes as well as IgA itself was usually raised in the lactating sheep. Lymph flow was increased and lymph globulin concentrations proportionally decreased in lactating ewes, irrespectively of whether they were infected with worms. It is suggested that these changes were caused by the increase in voluntary food intake which occurs during lactation.

Animals↗
PubMed1983

Local immunity and Ostertagia circumcincta: changes in the gastric lymph of sheep after a primary infection.

Some aspects of the kinetics of the primary local immune response to O. circumcincta were studied by monitoring the flow and composition of gastric lymph from 4 sheep for 3 weeks after infection with 50 000 larvae. A significant increase in the frequency of lymphoblasts in the lymph showed that all the sheep were responding immunologically to the parasites from day 8 onwards. However, considerable individual variation in degree and timing was evident in other aspects of the immune response; 2 animals responded with large increases in lymphocyte output which reached a peak on day 5 or day 10, whereas the main response in the other 2 sheep appeared to be inflammatory in nature, with large increases in lymph flow and eosinophil output which occurred during the third week of infection. No significant changes in the content of IgA or IgA anti-worm antibody were detected in the lymph, but pepsinogen concentrations were significantly raised from day 12 onwards.

Animals↗
PubMed1983

Local immunity and Ostertagia circumcincta: changes in the gastric lymph of immune sheep after a challenge infection.

Immunity to Ostertagia circumcincta was demonstrated in 5 previously infected sheep which were killed 10 days after challenge with 50 000 larvae. This immunity was expressed as a reduction in the number as well as the degree of development of the surviving parasites compared with those found in 6 control sheep. Gastric lymph was sampled from the immune group from 2 days before till 10 days after challenge and a secondary local immune response was detected. The main features of this response were a large increase in cell output in the lymph, especially in lymphoblasts and IgA-containing cells, which reached a peak on day 4 or 5, followed by a ten-fold increase in IgA immunoglobulin and IgA anti-worm antibody which reached a peak 7 or 8 days after challenge. The timing of these events suggested that the cellular, but not the IgA, response could have been involved in a putative mechanism which caused arrested development, although both components could have been implicated in mechanisms which may have caused expulsion of developing larvae.

Animals↗
PubMed1983

Immune exclusion, a mechanism of protection against the ovine nematode Haemonchus contortus.

The fate of exsheathed Haemonchus contortus larvae injected directly into the abomasal lumen was studied in groups of naive and hyperimmune sheep. Within 48 hours of challenge, more than 90 per cent of the larvae were lost from hyperimmune sheep. The larvae had a propensity to associate with the superficial mucus in both groups and, in naive sheep, approximately 50 per cent of the larvae entered glandular tissue within four hours of challenge. By contrast, although initially associated with the mucosal surface, larvae in immune sheep were excluded from the glandular tissues. It is postulated that the rapid loss of worms from the hyperimmune abomasum is a consequence of 'immune exclusion' and the possible mechanisms underlying this process are discussed.

Abomasum↗