Biomedical subjects

P C Allen

Publications and source records attributed to P C Allen.

At least 37 records · Page 2Linked to original sources

PubMed1997

Assessment of recombinant bovine somatotropin as an immunomodulator during avian coccidiosis: immunization with living oocysts.

Coccidiosis, a disease of great economic importance to the poultry industry, is generally controlled prophylactically by additions of anticoccidial drugs to the feed. However, increasing development of drug-resistant coccidia species has stimulated searches for alternative control methods, one of which is vaccination. As part of this effort, recombinant bovine growth hormone (rbST) was tested as a possible immune stimulator in combination with live oocyst vaccination. At a dose of 0.045 mg per chick, given by s.c. injection at 1 d of age, rbST did not improve immunity developed by immunization with 500 or 2,500 oocysts of Eimeria maxima as judged by weight gain and lesion scores. At a single dose of 0.09 mg per chick given at 1 d of age in combination with IMMUCOX, rbST provided some protection against challenge infection with Eimeria tenella but not Eimeria acervulina as judged by reduction in lesion scores. Treatment with 0.09 mg rbST per chick alone at 1 and 3 d of age was protective against challenge with E. tenella but not E. acervulina or E. maxima as judged by reduction in lesion scores. These results strongly indicate that rbST can act as an immune modulator in chickens infected with coccidia, and provide a basis for further investigations of its use as a vaccine adjuvant.

Adjuvants, Immunologic↗

PubMed1997

Effects of components of Artemisia annua on coccidia infections in chickens.

Four experiments were run to test the anticoccidial activity of dried Artemisia annua leaves and several of their chemical constituents for possible use as prophylactic feed additives. When fed over a period of 3 wk at a level of 5%, a dried leaf supplement of A. annua provided significant protection against lesions due to Eimeria tenella but not Eimeria acervulina or Eimeria maxima. When fed over a period of 5 wk at a level of 1% to chicks undergoing immunization with a live vaccine, it provided significant protection in partially immunized chicks against E. acervulina and E. tenella lesions from a dual species challenge infection. It also afforded lower mean lesion scores in challenged chicks immunized over a period of 5 wk. Artemisinin, an antimalarial component of A. annua, was present at a level of 0.034% in the dried leaf preparation. A 5% supplement thus afforded about 17 ppm artemisin. When the pure compound was fed at that level for a period of 3 wk, it protected weight gains and significantly reduced lesion scores attributable to E. tenella but not E. acervulina. Other components of A. annua, camphor and 1,8-cineole, at 119 ppm also protected weight gains, and reduced E. tenella lesion scores. Camphor reduced E. acervulina lesions. Artemisinin fed for 4 wk at levels of 2, 8.5, and 17 ppm significantly reduced oocyst output from separate E. acervulina and E. tenella infections and a dual species infection. Pure artemisinin thus appears to be effective against at least two coccidia species when used as a feed additive, and its activity may depend, in part, on the length of time it is administered before a challenge infection.

Analysis of Variance↗

PubMed1997

The effect of inhibitors of inducible nitric oxide synthase on chronic colitis in the rhesus monkey.

GI inflammation is associated with an increase in nitric oxide production and expression of the inducible isoform of nitric oxide synthase (iNOS). Using a spontaneous model of chronic colonic inflammation in rhesus monkeys, which shares morphological and clinical features with ulcerative colitis, we assessed the therapeutic benefit of administration of iNOS inhibitors. Sixteen colitic rhesus monkeys underwent an endoscopy procedure before commencement of the trial, and biopsies from three sites of the colon and plasma were collected. Monkeys were randomly assigned to three treatment groups and were administered by oral bolus 60 mg/kg/day L-N 6-(1-Iminoethyl) lysine, 60 mg/kg/day aminoguanidine or a placebo (0.9% NaCl) twice daily. Monkeys were sacrificed after 10 days, coIonic tissue from multiple sites was dissected and processed for histological and biochemical analysis. In rhesus colitis, diarrhea was characterized by a significant increase in fecal water content and daily fecal output. iNOS was localized immunohistochemically in plasma cells and neutrophils in the colonic mucosa and lamina propria, paralleled by enhanced iNOS gene expression determined by reverse-transcriptase polymerase chain reaction. Only L-N 6-(1-iminoethyl) lysine administration resulted in a significant reduction in systemic nitric oxide production, and neither of the iNOS inhibitors significantly reduced the histological inflammatory score nor ameliorated diarrheal symptoms. From these findings, we conclude that in this chronic, spontaneous model of colonic inflammation, administering iNOS inhibitors with this treatment regimen did not provide any major therapeutic benefit.

Administration, Oral↗

PubMed1996

Diets high in n-3 fatty acids reduce cecal lesion scores in chickens infected with Eimeria tenella.

Four experiments were run in which diets incorporating various levels of n-3 fatty acids (n-3FA) from fish (menhaden) oil or flax seed were tested for their abilities to reduce the severity of Eimeria tenella infections in young broiler chicks. The diets were fed from 1 d of age through 3 wk of age. Chickens were infected at 2 wk of age. Diets consisting of broiler starter ration supplemented with 2.5 to 10% fish oil, 10% flax seed oil, or 10% linseed oil significantly decreased cecal lesions and maintained weight gains as compared to unsupplemented diets. Light micrographs of ceca from chickens that consumed high n-3FA diets showed reduced parasite invasion and development. Short-term feeding of diets high in n-3FA to young chicks may be a practical method for reducing production losses from cecal coccidiosis.

Animals↗

PubMed1996

Association of lowered plasma carotenoids with protection against cecal coccidiosis by diets high in n-3 fatty acids.

A series of four experiments was run to assess the effectiveness of diets containing high amounts of n-3 fatty acids in reducing the pathological effects of cecal coccidiosis in chickens caused by Eimeria tenella. To determine whether the dietary effects were related to development of oxidative stress, plasma samples were analyzed for tocopherols and carotenoids. Plasma vitamin E (alpha-tocopherol) values were not consistent between experiments. Total plasma carotenoids, however, were significantly decreased by 2.5 to 20% diet supplementation with fish oil in several experiments. These decreases coincided with significant reductions in lesion scores. Under the experimental conditions, total plasma carotenoid concentrations may serve as a sensitive indicator for oxidative stress, which may be a factor in reducing cecal lesions in E. tenella infections.

Animals↗

PubMed1995

Comparison of 16S rRNA sequences of segmented filamentous bacteria isolated from mice, rats, and chickens and proposal of "Candidatus Arthromitus".

Segmented filamentous bacteria (SFB) are nonpathogenic bacteria that are commonly found attached to the intestinal walls of many animals. Until now, these bacteria have not been cultured in vitro. Recently, a 16S rRNA sequence analysis revealed that SFB isolated from mice represent a distinct subline within the Clostridium subphylum of the gram-positive bacteria. Since SFB isolated from mice, rats, and chickens are known to be host specific, we investigated the phylogenetic relationships among SFB obtained from these three hosts. Total DNAs from the intestinal floras of chickens and rats were used as templates for PCR amplification of 16S rRNA genes. PCR products were cloned and screened by a dot blot hybridization procedure to identify homologous sequences that cross-reacted with mouse SFB-specific oligonucleotide probes. A phylogenetic analysis of these 16S ribosomal DNA sequences revealed that SFB isolated from these three hosts form a natural group, which is peripherally related to the genus Clostridium sensu stricto (group I Clostridium). The SFB obtained from chickens, rats, and mice had closely related, albeit different, 16S rRNA gene sequences. The observed levels of 16S rRNA sequence divergence, ca. 1.5 to 3%, together with host specificity, suggest that SFB isolated from mice, rats, and chickens represent different species and that coevolution of the SFB and their hosts occurred. "Candidatus Arthromitus" is proposed as the provisional generic name for this group of organisms.

Animals↗

PubMed1993

Effects of formaldehyde fumigation of housing on carotenoid pigmentation in three breeds of chickens.

Three breeds of chickens (two broiler breeds, A and B, and one layer breed, C) were raised from 1 day to 3 wk of age in either standard housing or housing additionally fumigated with formaldehyde. Groups of chicks from each breed in both housings received either regular poultry starter ration or this ration supplemented with marigold meal. At 3 wk of age, chicks of all three breeds had higher (111, 113, and 115%) mean body weights when raised in fumigated housing. There was no significant effect of supplemental carotenoids on body weight. Chicks of all three breeds raised in fumigated housing had significantly higher plasma carotenoid concentrations when fed either regular or supplemented feed, and, with the exception of Breed A on regular feed, also had significantly increased skin carotenoid values. No significant differences among breeds in plasma or skin carotenoid values were seen in chicks fed regular ration. However, significant differences were seen among groups of chicks fed supplemental carotenoids. The layer breed, C, had the highest percentage increase in carotenoid pigmentation when fed the carotenoid-supplemented diet in fumigated housing.

Animal Feed↗

PubMed1993

Effect of atherogenic diet on chicken plasma lipids and lipoproteins.

Adult male White Leghorn chickens were used in an experimental model system to study atherogenesis, and the effects of an atherogenic diet on plasma lipoprotein composition including carotenoids were determined. This model also included treatment with diazepam, a drug known to reduce formation of atherogenic plaques. After 6 wk consumption of a high-cholesterol, high-triglyceride diet, chickens had mean total plasma cholesterol, triglyceride, and carotenoid concentrations that were significantly increased over those from chicks that consumed the standard diet. Diazepam treatment had no significant effect on whole plasma concentrations of these lipids. Total body weight gain was unaffected by diet, but liver weight expressed as percentage of body weight was significantly increased in chickens that consumed the atherogenic diet. High density lipoprotein (HDL) and low density lipoprotein (LDL) fractions were isolated from plasma samples by ultracentrifugation. The atherogenic diet increased the carotenoid, cholesterol, and protein content of the LDL fractions but not the HDL fractions.

Animals↗

PubMed1992

Effect of coccidiosis on the distribution of dietary lutein in the chick.

A series of experiments was run to determine whether the distribution of dietary carotenoids in chick plasma and tissue was dependent upon a saturable carrier, and to observe how infection with Eimeria acervulina affected this distribution. Broiler (Hubbard x Hubbard) and Sex Sal (Rhode Island Red x White Rock) chicks were fed a white corn and soybean meal-based diet supplemented with varying levels of a commercial lutein concentrate. Plasma, small intestine, and liver were analyzed for lutein. In the first experiment, mean plasma values in control broiler chicks increased linearly from 0 to 200 ppm supplementation. Mean plasma values of infected chicks were decreased an average of 71% as compared with controls, and reached a plateau between 100 and 200 ppm dietary lutein. In the second experiment, plasma, small intestinal, and liver lutein levels in broiler chicks reached a plateau between 200 and 500 ppm. In the third experiment, plasma and liver values in Sex Sal chicks leveled off between 250 and 500 ppm whereas levels in the small intestine increased linearly. Infection of the Sex Sal chicks at 3 wk of age with E. acervulina caused plasma lutein levels to be reduced about 88%, small intestinal levels 76%, and liver levels 72%. Supplementation with 500 ppm resulted in higher proportions of lutein in tissues. Infection with E. acervulina shifted the ratios to even higher proportions in the tissues at all supplementation levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Long segmented filamentous organisms in broiler chicks: possible relationship to reduced serum carotenoids.

Over the past several years, broiler-flocks at the author's laboratory have exhibited low serum carotenoid levels. This phenomenon has not been related to exceptionally low carotenoids in the feed or to known protozoan or viral infections. However, long segmented filamentous organisms (LSFO) have been identified in the pale chicks. An inverse correlation between LSFO counts and serum carotenoid levels was not observed, but prevention of LSFO infection consistently resulted in higher carotenoid values. Young chicks were very susceptible to naturally acquired LSFO infection, but the organisms decreased in number with time and became very difficult to find by the time the chicks were 7 wk old. Segments of LSFO containing endospores were detected in mucosal smears. This observation, along with the extreme ease of natural infection, suggests that LSFO are transmitted by dust-borne spores. Transmission can be prevented by fumigation of housing with formaldehyde vapors.

Animals↗

PubMed1992

Comparative study of long, segmented, filamentous organisms in chickens and mice.

No transmission of long, segmented, filamentous organisms (LSFO) from a laboratory mouse strain (Mus musculus) to a domestic broiler chicken strain (Gallus domesticus) occurred by oral dosing with mouse mucosal and fecal preparations, even in hydrocortisone-treated chicks. Transmission of chicken LSFO to laboratory mice was attempted, but the results were confounded by the mice having been already infected with LSFO. However, the morphologic characteristics of the LSFO in the dosed mice suggested that transmission of chick LSFO did not occur. Mouse LSFO, as detected in carbol thionin-stained mucosal smears, are generally wider, longer, and have slightly different morphologic characteristics than chicken LSFO. The results of these studies suggest that the LSFO in mice and chickens may be two distinct species.

Animals↗

PubMed1990

Effect of dietary cholesterol on the lipoprotein profile and binding of radioiodinated lipoproteins to hepatic membranes in the cockerel (Gallus domesticus).

1. Cockerels fed a cholesterol-supplemented diet experienced a marked elevation of lipoprotein particles of density less than or equal to 1.006 g/ml (VLDL) and a diminution of lipoprotein particles of density 1.02-1.05 g/ml (LDL). 2. Unlike VLDL of some cholesterol-fed animals, cholesterol-fed cockerel VLDL did not display beta-mobility on agarose gel electrophoresis. 3. [125I]LDL and [125I]HDL binding to cockerel liver membranes was not affected by cholesterol feeding. 4. Different lipoprotein types appear to bind to a common site on cockerel liver membranes. 5. The results suggest that liver cells of cockerels may not possess LDL binding sites that are analogous to those of mammalian species.

Animals↗

PubMed1990

Effect of feed deprivation on hepatic membrane and lipoprotein fluidity and binding of lipoproteins to hepatic membranes in the chick (Gallus domesticus).

1. Male chicks were deprived of feed for 48 hr to study the effect of metabolic stress on hepatic membrane and lipoprotein fluidity and binding of radioiodinated lipoproteins to hepatic membranes. 2. Plasma levels of low density lipoprotein (LDL) and high density lipoprotein (HDL) were markedly and slightly elevated, respectively. 3. There was a reduction in lipoprotein and hepatic membrane fluidity. 4. Binding of [125I]LDL, but not [125I]HDL, to hepatic membranes was decreased. 5. It is suggested that a reduction in the fluidity of LDL and/or hepatic membranes impedes LDL catabolism in vivo.

Animals↗

PubMed1988

The effect of Eimeria acervulina infection on plasma lipids and lipoproteins in young broiler chicks.

In young broiler chicks inoculated with 2 x 10(6) sporulated oocysts of Eimeria acervulina per bird, total plasma lipids were significantly depressed compared with controls in the first week after inoculation. The lowest level observed was at 5 days post-inoculation (d.p.i.), at which time the chick host is known to experience malabsorption in the chick host (Ruff and Wilkins, 1980). Analysis of plasma components of infected chicks at 4 and 7 d.p.i. showed that triglycerides, total cholesterol, free fatty acids, pigments and total protein were significantly decreased compared with controls. At 7 d.p.i., reduction of total cholesterol reflected mainly reduction in high density lipoprotein (HDL) cholesterol. However, the ratio of HDL cholesterol/total plasma cholesterol was not significantly different from the control ratio. Density gradient ultracentrifugation of chick plasma separated lipoproteins into three main fractions: portomicrons plus very low density lipoproteins (PM + VLDL), low density lipoproteins (LDL) and HDL. These fractions were analyzed for lipid content. Infection with E. acervulina caused (1) significant reduction in the triglyceride and cholesterol contents of the PM + VLDL fraction at 3 and 5 d.p.i., (2) significant reduction of LDL cholesterol at 9 d.p.i. and LDL phospholipid at 5-9 d.p.i., and (3) significant reduction of HDL cholesterol at 3-9 d.p.i. and HDL phospholipid at 5-9 d.p.i. Starvation of uninfected chicks for 48 h caused significant reduction in plasma triglycerides and phospholipids, but an increase in total cholesterol. Density gradient ultracentrifugation showed that the changes in these components reflected mainly reduction of the lipids in the PM + VLDL fraction. The LDL fractions, however, appeared more intense than those of the controls and contained more cholesterol and phospholipids. These results suggest that changes at 3 and 5 d.p.i. in the plasma lipoprotein pattern of chicks infected with E. acervulina most closely resemble changes seen in chicks starved for 48 h as far as PM + VLDL fraction is concerned. However, changes seen from 7 to 9 d.p.i. involve the LDL and HDL fractions and may reflect alterations in lipid and/or lipoprotein synthesis in the liver and intestine.

Animals↗

PubMed1987

Effect of Eimeria acervulina infection on chick (Gallus domesticus) high density lipoprotein composition.

1. Plasma high density lipoprotein (HDL), the principal carotenoid carrier in broiler chicks, was analyzed at zero time and 3, 5 and 7 days after inoculation of chicks with the intestinal coccidial parasite, Eimeria acervulina. 2. Infection caused significant decreases in total HDL mass from 3 through 7 post-inoculation (PI), and decreases in relative percents of protein and carotenoids, and relative increases in phospholipid and cholesterol esters by 7 days PI. 3. Carotenoid content correlated best with protein content (principally apolipoprotein A-I) throughout the experiment. 4. Findings emphasize the importance of the small intestinal mucosa as a source of plasma HDL in the broiler chick, and suggest that apolipoprotein A-I is the binding site for HDL carotenoids.

Animals↗

PubMed1987

Physiological responses of chicken gut tissue to coccidial infection: comparative effects of Eimeria acervulina and Eimeria mitis on mucosal mass, carotenoid content, and brush border enzyme activity.

Broiler chicks, 3 to 4 wk of age, were inoculated with either Eimeria acervulina or E. mitis, and mucosal dry weights, brush border enzyme activities, and carotenoid contents as well as plasma carotenoid levels were measured at 3, 5, and 7 days postinoculation (PI). At 5 and 7 days PI mucosal dry weights, brush border enzyme activities, and carotenoid contents were significantly decreased at primary sites of infection (duodenum, E. acervulina; lower small intestine, E. mitis). In contrast, at sites remote from infection, mucosal dry weights and brush border enzyme activities were significantly increased above control values. However, mucosal carotenoid contents were significantly decreased. Between 5 and 7 days PI mucosal renewal as signalled by increases in dry weight was accompanied by increases in brush border enzyme activities. However, mucosal carotenoid contents were further decreased. High correlations were found between plasma carotenoid levels and total mucosal carotenoids in control and coccidia-infected chicks, but not in 48-h-starved chicks. Infection with coccidia increased this correlation, and the increase with E. acervulina infection was significant. These data indicate that hyperplastic and renewing mucosal tissue is defective in absorbing carotenoids, and further, that there is no direct relationship between mucosal carotenoid content and brush border enzyme activities. Apparently carotenoids are not mobilized from body depots during the first week of coccidial infections as they are during 48-h starvation.

Alkaline Phosphatase↗

PubMed1984

The effects of Eimeria acervulina infection on the metabolism of chick duodenal tissue.

Broiler chicks, 2--3 weeks old were infected with eimeria acervulina, and the metabolism and ultrastructure of the infected duodenal tissue were studied during the period 3--14 days after inoculation (DAI). Between 4 and 5 DAI duodenal rings showed an increase in C-1/C-6 ratios of CO2 evolved from glucose as well as decreases in the rates of oxidation of glucose and octanoic acid. Between 4--7 DAI mitochondria from infected epithelial layers had reduced rates of octanoic acid and alpha-ketoglutaric acid oxidation as compared to controls. Electron microscopic observations confirmed the biochemical findings. At 5--6 DAI mitochondria in many uninfected cells were progressively swollen and then vacuolated as the cristae appeared to break down. Mitochondria in cells which contained parasites did not show these changes.

Animals↗

PubMed1984

Changes in pancreatic hormones associated with coccidiosis.

Compared to controls, 2- to 3-week-old broiler chicks inoculated with Eimeria acervulina (2 X 10(6) sporulated oocysts/bird) had significantly lower mean plasma levels of pancreatic insulin (PI) and pancreatic glucagon (PG) between 4 and 6 days after inoculation (DAI). In further trials with E. acervulina infections, significant depressions in mean PG were seen at 7 DAI and appeared to be associated with a high inoculating dose. Mean plasma levels of glucagon-like immunoreactants (GLI) were significantly increased from 3 to 8 DAI. This increase was repeatedly demonstrable at 7 DAI and was dose dependent between doses of 2 X 10(3) and 2 X 10(5) sporulated oocysts/bird. Compared to controls, chicks inoculated with E. tenella (2 X 10(5) sporulated oocysts/bird) had significantly higher mean plasma levels of PI at 4, 7, and 8 DAI and a significantly lower value at 6 DAI. Mean plasma PG values were significantly lower at 5 and 6 DAI. Mean plasma levels of GLI did not differ significantly from controls throughout the experiment. Changes in the hormones measured in both infections showed no direct significant statistical relationship with changes in pancreas weight, body weight, blood glucose or liver glycogen. However, an inverse correlation was found between plasma GLI and plasma pigment levels with time after infection in E. acervulina infections. The coincidence of plasma GLI increase with increased oocyst dose and diminished plasma pigment in E. acervulina infections, and the fact that E. tenella infection did not elicit a significant increase in plasma GLI, suggests that elevated GLI is closely associated with mucosal damage in the upper small intestine caused by E. acervulina.

Animals↗