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Biomedical subjects

C C Norton

Publications and source records attributed to C C Norton.

At least 19 recordsLinked to original sources
PubMed1995

Ultrastructural observations on the third-generation merozoites of Eimeria tenella in chicks.

The fine structure of the third-generation merozoites of Eimeria tenella is described from caecal enterocytes of chicks 120 h after experimental infections. The merozoites conformed to the general eimerian pattern except that they were bounded by two unit membranes. Young gamonts also conformed to the general eimerian pattern, and were limited by an outer unit membrane and an interrupted inner membrane. Enterocytes invaded by third-generation merozoites showed a loss of microvilli and large blebs that protruded into the caecal lumen. These blebs appeared to contain only cytoplasm and not any cell organelles.

Animals↗
PubMed1994

Variations in oocyst output associated with Cryptosporidium baileyi infections in chickens.

Groups of birds, aged 2, 16 and 30 days, were experimentally infected with 400, 20,000 or 1,000,000 oocysts of Cryptosporidium baileyi. The faecal oocyst output for each group was determined by collection of faeces on Days 0, 5, 7 and 13-21 post-infection (p.i.). The duration of patency of infection, as determined by oocyst excretion, declined more rapidly in the older age groups but persisted longer in birds challenged with the lower oocyst numbers.

Age Factors↗
PubMed1993

Immunisation of lambs against coccidiosis.

Two groups of twin lambs, kept with their dams at pasture, were given 10,000 oocysts of Eimeria crandallis and 10,000 oocysts of E ovinoidalis either at birth only, or on four occasions at weekly intervals. A further group received 1000 oocysts of each species three times a week in a 'trickle infection' from birth to 21 days of age. All these lambs, together with a susceptible control group were challenged with 100,000 oocysts of each species at 28 days of age. A fifth group received no inoculations throughout. Bodyweight, faecal consistency and oocyst output were monitored up to nine weeks of age. There was no clinical response to any of the immunising inoculations and no change in the faecal consistency, but the group infected at birth grew significantly faster than the uninfected controls. The pattern of oocyst output showed that only E crandallis developed fully in the newborn animal, but both species multiplied in seven-day-old lambs. The challenge infection produced 80 per cent mortality in the susceptible control group and 20 per cent mortality in the group which had received only one immunising dose at birth. The other immunised groups were well protected and gained more weight than the unchallenged controls. At nine weeks of age, the weight gain of the lambs which had received the 'trickle infection' was significantly higher than that of all the other groups.

Animals↗
PubMed1993

Ultrastructural observations on caecal epithelial cells invaded by first-generation merozoites of Eimeria tenella in vivo.

Transmission electron microscopy was used to study the effects of invasion of caecal epithelial cells by first-generation merozoites of Eimeria tenella. At 53 h post-infection, merozoites were found within mature meronts and in enterocytes of the crypt epithelium. Following merozoite invasion, the terminal web of microfilaments of the invaded cell was disrupted and cell extensions were present on the enterocyte surface. There was a marked morphological alteration of the host cell resulting in loss of microvilli and extensive bulging of cytoplasm into the crypt lumen. Multiple invasion of enterocytes and invasion of goblet cells were observed. Large numbers of mast cells infiltrated the mucosa, identified by the metachromatic staining of their granules, and were found within the lamina propria, epithelium and lumen. Merozoites were found within mast cells and lymphocytes within the lumen.

Animals↗
PubMed1991

Ultrastructural studies of the effects of the ionophore lasalocid on Eimeria tenella in chickens.

The ultrastructural development of Eimeria tenella was studied in experimentally infected chicks fed 90 ppm lasalocid, an ionophorous anticoccidial antibiotic. Drug treatment was timed to target-specific endogenous stages. At 6 h after infection, many sporozoites within the epithelium showed degradation as a result of drug action. Only a few intact sporozoites were seen. The drug caused outer-membrane blistering, large surface swellings and enlarged mitochondria in both first- and second-generation merozoites. No effect on the gamonts was discerned.

Animals↗
PubMed1991

Comparison of resistance level and circulating IgG response in chickens experimentally inoculated with a multiple or single immunizing doses of Eimeria acervulina.

Two immunizing methods (Trickle or single immunizing doses) against E. acervulina were tested in chickens. The effects of immunization and challenge upon growth, oocyst output and circulating antibodies response (IgG) were compared. Neither immunization method produced pathogenic effects, similar numbers of oocysts were produced, and the levels of IgG in serum were similar and low in each case. After the challenge, immunized birds showed a high level of resistance but susceptible controls produced very large number of oocysts and showed a marked reduction in the growth. Birds immunized by a trickle infection produced oocysts on two days only and the total number of oocysts per bird was very low, whereas those immunized by a single infection produced oocysts over a period of nine days and the total number of oocysts was higher. Susceptible and birds immunized by a single inoculation showed similar IgG concentration and these were statistically higher than birds immunized by a trickle infection. In susceptible birds the kinetic of IgG was delayed about 4 days.

Animals↗
PubMed1989

Observations on the endogenous stages of Eimeria crandallis in domestic lambs (Ovis aries).

Lambs reared coccidia-free were inoculated orally with various numbers of sporulated oocysts of E. crandallis and were killed between 1 and 22 days after inoculation; tissues were examined histologically. Sporozoites were seen 1, 2 and 3 days after inoculation (DAI) in crypt epithelial cells in the mid-jejunum. Infected cells migrated into the lamina propria where the parasite within them developed into a first-generation meront containing about 250,000 merozoites at 10 DAI. A second generation of meronts was seen at 10-12 DAI, each containing up to about 10 merozoites, situated mainly at the bases of crypts in the jejunum and ileum but also in the caecum. From 11 DAI pro-gamonts were seen which were enveloped by the host cell nucleus and which divided in synchrony with the host cell for an undetermined number of generations. Mature gamonts began to develop from them by 16 DAI. Oocyst output began at 16 DAI and rose to a peak at about 22 DAI. Up to 10(8) oocysts were produced per oocyst inoculated. They showed wide variation in size and colour.

Animals↗
PubMed1987

Ultrastructural studies of the effects of amprolium and dinitolmide on Eimeria acervulina macrogametes.

Medication of chicks with 125 ppm amprolium or dinitolmide adversely affected oocyst sporulation of Eimeria acervulina (Weybridge strain). Dinitolmide delayed oocyst production and no oocyst wall formation was seen up to 168 h post infection. Both drugs caused large numbers of abnormally small wall-forming bodies to be produced in the macrogametes. In amprolium-fed chicks, abnormal oocyst wall formation was seen. It was concluded that the main drug action was against wall forming bodies of type 2.

Amprolium↗
PubMed1986

Coccidia of the domestic goat Capra hircus, with notes on Eimeria ovinoidalis and E. bakuensis (syn. E. ovina) from the sheep Ovis aries.

Eimerian oocysts were found in 98% of 422 faeces samples from goats in SE England. It was found that 74% of the samples contained thousands or tens of thousands of oocysts/g. Kids less than 1 year old had higher oocyst counts than yearling or adult goats. Nine species of Eimeria were identified, and 65% of the samples contained 3-5 species. The most prevalent species were E. arloingi (94%), E. hirci (69%), E. christenseni (64%) and E. caprina (55%). E. ninakohlyakimovae (48%), E. alijevi (42%) and E. apsheronica (23%) were common, and E. jolchijevi (8%) and E. caprovina (4%) were comparatively rare. Developmental stages of E. caprina destroyed the crypt epithelium in the mucosa of the large intestine, causing severe haemorrhagic enteritis similar to that produced by E. ninakohlyakimovae. The literature on Eimeria species in sheep and goats is reviewed and, on the grounds of priority, E. bakuensis is the correct name for E. ovina in sheep.

Animals↗
PubMed1986

Avian coccidiosis: the administration of encapsulated oocysts.

Oocysts of fowl coccidia, suspended in a 12% aqueous solution of alginic acid, were dropped into 5% calcium chloride solution to form beads. Following ingestion by chicks, excystation of sporozoites was not affected. Oocyst viability was best when beads were air-dried to 33% of their original weight and stored in airtight containers at 4 degrees C. Infectivity was fully maintained for 8 weeks. Trickle infection, using beads administered orally to 2- or 3-week-old chickens, or mixed daily in food of chicks from 1-day-old, established a high level of immunity. This method of oocyst administration offers some practical advantages for the conduct of immunity and chemotherapy experiments.

Alginates↗
PubMed1985

Morphological effects of arprinocid on developmental stages of Eimeria tenella and E. brunetti.

Medication of chicks with 70 p.p.m. arprinocid in the food, starting 2 days prior to inoculation with Eimeria tenella, resulted in decreased oocyst production and oocyst sporulation. The main morphological alteration seen during the development of the second-generation schizont was a reduction in the number of second-generation merozoites due to incomplete merogony, resulting in large masses of vacuolated residual cytoplasm. In places around the developing macrogamete the integrity of the parasitophorous vacuole was lost by either the host cell limiting membrane making contact with the parasite pellicle, or the disruption of one or both of these surfaces apparently brought about by the intervention of the host cell mitochondria. Thirty p.p.m. arprinocid reduced sporulation of the oocysts of E. brunetti and caused enlargement of the perinuclear space in the late merozoites and swelling of the endoplasmic reticulum around wall-forming bodies II.

Adenine↗