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Biomedical subjects

P B Hamilton

Publications and source records attributed to P B Hamilton.

At least 55 records · Page 3Linked to original sources
PubMed1987

Metabolism of lutein diester during aflatoxicosis in young chickens.

Young chickens were fed from hatching until 3 wk of age with a white corn-soy diet amended with lutein diester to supply 25 micrograms lutein/g diet and with varying amounts of aflatoxin (0, 1, 2, 4, and 8 micrograms/g diet). The lutein diester was added as a stabilized, microencapsulated extract of marigold (Tagetes erecta) petals. Aflatoxin had no significant effect on the partial conversion of lutein diester to lutein monoester and lutein that occurs in the jejunum of normal chickens. The concentration of lutein in the jejunal mucosa was increased slightly by intermediate levels of aflatoxin and depressed by higher levels. Aflatoxin depressed lutein (the dominant form) in serum by up to 40%. Aflatoxin enhanced the lutein accumulation in the liver as the monoester (four-fold) and diester (12-fold). Only minor effects of aflatoxin on the carotenoid content of the toe webs were noted in birds fed lutein diester. These results imply that the main effects of aflatoxin on the utilization of lutein diester are to impair the absorption of lutein, which is an intestinal product of dietary lutein diester, and to sequester lutein as lutein monoester and lutein diester in the liver.

Animals↗
PubMed1986

Evidence for differential absorption of zeacarotene, cryptoxanthin, and lutein in young broiler chickens.

The intestinal tracts of young chicks, fed a yellow corn-soy-based diet from hatching until 3-weeks-old, were excised and divided into five segments equal in length. The contents of the segments were removed and analyzed for content of zeacarotene, cryptoxanthin (monohydroxycarotenoid), and lutein (dihydroxycarotenoid) by high pressure liquid chromatography. Cryptoxanthin, which is poorly absorbed by young chickens, served as a nonabsorbed reference material. The ratios of zeacarotene to cryptoxanthin were not reduced significantly (P less than .05) from that in the ingested feed until the ileal region was reached. The ratios of lutein to cryptoxanthin were reduced significantly (P less than .05) in the duodenal and upper jejunal region. The finding of different sites of absorption for zeacarotene and lutein, combined with the poor absorption of cryptoxanthin, suggests the existence in chickens of regulatory mechanisms for carotenoids.

Animals↗
PubMed1986

Lutein as a model dihydroxycarotenoid for the study of pigmentation in chickens.

A model for the study of pigmentation in young chickens is described in which a white corn-soy based diet supplemented with varying amounts of free lutein (0, 5, 10, 20, 40, and 80 micrograms/g diet) was fed from hatching until 3 weeks of age. The carotenoid content of tissues dissected from chicks of the various groups was measured by high pressure liquid chromatography. In intestinal contents, three forms of lutein were found, with lutein monoester greater than free lutein greater than lutein diester. In the serum, free lutein (96%) and lutein monoester (4%) were found. In the liver, free lutein (80%), monoester (20%), and traces of diester were found. In the integument (toe web), diester greater than monoester approximately equal to free alcohol were found. In each tissue, the concentrations were directly proportional to the dietary concentration of free lutein. The simplest explanation of the data appears to be that part of the free lutein in the diet is esterified during its passage down the intestinal tract and, regardless of its status when absorbed, it is transported in the body as the free alcohol. When it enters depot sites such as the integument, lutein is deposited mainly as esters, presumably as the result of local enzymatic activity.

Animals↗
PubMed1986

Canthaxanthin as a model for the study of utilization of oxycarotenoids by chickens.

A white corn-soy diet amended with varying levels (0, 5, 10, 20, 40, and 80 ppm) of canthaxanthin, a red diketocarotenoid available by chemical synthesis, and fed to young broiler chickens for 3 weeks has the attributes of a useful experimental model for the study of absorption, transport, and deposition of oxycarotenoids. On high pressure liquid chromatography of extracts of the diet and tissues of the birds, canthaxanthin predominated over the background level of nonspecific carotenoids. The concentrations of canthaxanthin found in the contents of the jejunum and large intestine and in the serum, liver, and toe web were directly proportional to the dietary concentration. Departure from such linear relationships would signal loci of action for factors affecting pigmentation. Analysis of toe webs, an integumentary depot site for carotenoids, revealed that the concentrations of canthaxanthin and two other compounds, one more polar and the other less polar than canthaxanthin, were proportional to the dietary concentration of canthaxanthin. Saponification converted the less polar compound to the more polar compound. The behavior of these compounds in response to dietary canthaxanthin, to chromatography, and to saponification can be explained by assuming that canthaxanthin, a diketocarotenoid, was partly reduced to a ketohydroxy carotenoid (hydroxyechinenone) whose hydroxyl group is acylated to form an ester. These products represent new metabolic reactions in poultry.

Animals↗
PubMed1986

Absorption, transport, and deposition in chickens of lutein diester, a carotenoid extracted from marigold (Tagetes erecta) petals.

Young broiler chickens were fed from hatching until 3 weeks of age with a white corn-soy diet amended with varying amounts of lutein diester to supply 0, 5, 10, 20, 40, and 80 micrograms free lutein/g diet. The lutein diester was added as a stabilized, microencapsulated extract of marigold (Tagetes erecta) petals. The concentrations of lutein diester, lutein monoester, and lutein in the contents of the jejunum and large intestine and in serum, liver, and toe web from these birds were measured by high pressure liquid chromatography. The contents of the jejunum and large intestine contained a mixture of lutein diester, lutein monoester, and lutein. The serum contained lutein (approximately 90%), lutein monoester (approximately 10%), and traces of lutein diester. The liver contained the three carotenoid classes in ratios reflecting the serum ratios. The ratios in toe web, an integumentary depot site, were reversed with lutein diester much greater than lutein monoester greater than lutein. The concentrations of each class in each tissue bore a linear relationship to the concentration of lutein diester in the diet. A simple explanation for these data is that the dietary lutein diester was hydrolyzed mainly to lutein, which was absorbed through the intestinal wall into the blood stream where it was transported to the liver, a storage site, and to the integumentary sites where it is esterified to lutein diester which is the main depot form.

Animals↗
PubMed1986

3'-Oxolutein, a metabolite of lutein in chickens.

3'-Oxolutein (3-hydroxy-3'-oxo-beta,epsilon-carotene) was isolated using high performance liquid chromatography (HPLC) from the tissues and egg yolks of chicken fed a diet high in lutein and free of detectable 3'-oxolutein. It was identified by HPLC retention time, absorption spectrum identical to lutein and its esters, disappearance under alkaline conditions without giving rise to lutein, formation of an alkali labile palmitate, formation of a 2,4-dinitrophenylhydrazone, and reduction to lutein from which the dipalmitate was prepared. In each instance the isolated compound behaved identically with authentic 3'-oxolutein prepared by nickel peroxide oxidation of lutein. The order of ratios of lutein to 3'-oxolutein in the various tissues from laboratory and field birds was, in general, intestinal contents greater than intestinal mucosa greater than serum greater than liver approximately toe web approximately egg yolk greater than bile. This order was consistent with the hypothesis that lutein was oxidized to 3'-oxolutein in the liver, which, at least in part, was excreted via the bile into the intestinal lumen where it was diluted with dietary lutein. The remainder of the 3'-oxolutein formed in the liver presumably went into the serum where it was transported to depot sites. The ratio of lutein to 3'-oxolutein in the toe webs of broilers varied with their diet and pigmentation status. Amounts of 3'-oxolutein were found in quail and turkey egg yolks. This previously unreported lutein oxidative capability of liver extends the previously known metabolic acylation and deacylation reactions in poultry.

Animals↗
PubMed1985

Production of zearalenone, T-2 toxin, and deoxynivalenol by Fusarium spp. isolated from plant materials grown in North Carolina.

Fusarium spp. isolated from plant materials grown in the hot, humid climate of North Carolina were tested for production of mycotoxins. Isolates of F. acuminatum, F. graminearum, F. moniliforme, F. oxysporum, and F. solani produced zearalenone while isolates of F. equiseti and F. graminearum produced T-2 toxin and deoxynivalenol, respectively. This is the first report of zearalenone production by F. solani. The toxins were identified by capillary gas chromatography-mass spectrometry. These findings suggest that there are toxigenic strains of Fusarium indigenous to the warmer regions of the USA and that fasariotoxicoses of animals in this region are not necessarily the result of importing toxic grains from the cooler, upper midwestern USA.

Animal Feed↗
PubMed1985

Aflatoxin effects in white Leghorn chickens selected for response to sheep erythrocyte antigen. 1. Body weight, feed conversion, and temperature responses.

Chickens from lines selectively bred for high and low antibody response to sheep red blood cell antigen and reciprocal crosses between them were fed diets containing 0, 1, 2, 3, and 6 micrograms of total aflatoxin/g diet from 2 to 42 days of age. Low-line birds, although larger, did not differ from the high-line birds in feed consumption, feed conversion, surface, or cloacal temperatures. Differences between crosses and parental lines varied according to the particular trait. Responses to dietary aflatoxin were similar regardless of population. Aflatoxin depressed body weight, feed consumption, and feed conversion at 14 days and subsequent ages with the effect on body weight and feed consumption occurring at lower levels than that noted for feed conversion. Although aflatoxin did not alter cloacal temperatures, there were progressive decreases in surface temperatures at 2 micrograms/g and higher.

Aflatoxins↗
PubMed1985

Aflatoxin effects in white Leghorn chickens selected for response to sheep erythrocyte antigen. 2. Serological and organ characteristics.

Aflatoxin was fed to chickens from lines selected for high and low antibody response to sheep erythrocyte (SRBC) antigen and reciprocal crosses between the two lines. Differences were found among populations for liver, bursa, and thymus weight and antibody production to SRBC but not for spleen weight or heterophil: lymphocyte ratios. Dietary aflatoxin depressed absolute and relative weights of bursae and thymi and absolute weights of livers and spleens. Relative to body weight, however, liver and spleen weights increased. There was a large decrease in liver metabolism and a dramatic increase in heterophil: lymphocyte ratios when 5700 ppb of aflatoxin was fed, but no alteration in antibody production to SRBC antigen was detected. Population by response to aflatoxin interactions were not significant for any of the traits measured except bursa and spleen weights, suggesting a general response to this mycotoxin among lines of chickens known to be immunologically different.

Aflatoxins↗
PubMed1984

Simultaneous occurrence of deoxynivalenol, zearalenone, and aflatoxin in 1982 scabby wheat from the midwestern United States.

Thirty-three samples of wheat of the 1982 crop year from Kansas and Nebraska were analyzed for deoxynivalenol, T-2 toxin, zearalenone, and aflatoxin. Deoxynivalenol was identified in 31 of 33 samples, zearalenone was identified in 3 of 33 samples, and aflatoxin B1 was identified in 23 of 31 samples. One 1982 wheat sample from Illinois and one from Texas were also contaminated with deoxynivalenol at 1,200 and 600 ng/g, respectively. None of the samples contained detectable T-2 toxin. The mean concentration of deoxynivalenol was 1,782 +/- 262 ng/g, and the concentrations of aflatoxin B1 ranged from 0.8 to 17.0 ng/g, with a mean of 3.37 +/- 0.7. Zearalenone concentrations of the three positive samples were 35, 90, and 115 ng/g. However, density segregation of two other samples which tested negative yielded light fractions, comprising less than 2% of the samples, contaminated at 230 and 254 ng of zearalenone per g; calculated zearalenone concentrations for these two samples were below the limit of detection of the method. The high frequency of aflatoxin B1 and deoxynivalenol in wheat from the 1982 crop is unprecedented, as is the simultaneous contamination of some samples with deoxynivalenol, zearalenone, and aflatoxin B1.

Aflatoxins↗
PubMed1984

Correlation of aflatoxin contamination with zinc content of chicken feed.

Feed samples from chicken houses in five commercial chicken operations were analyzed for Zn, Mn, Fe, Cu, Cd, and aflatoxin content. Mean aflatoxin content of these samples was 14 ppb (14 ng/g) as opposed to 1.2 ppb in samples taken when the feed was made. Aflatoxin content of the feed samples correlated (r = 0.325) significantly (P < 0.05) with Zn content but not with Mn, Fe, or Cu, all of which correlated significantly with Zn. Zn content of unamended feed (<20 ppm [20 mug/g]) is normally supplemented with a mineral premix containing Zn, Mn, Fe, and Cu to meet the nutrient requirements of chickens (40 ppm of Zn). The mean zinc concentration of the feed samples (117 ppm) was about threefold greater than the nutrient requirement and ranged from 58 to 162 ppm in individual samples. These field survey results parallel earlier reports of augmented production of aflatoxin in monocultures of aflatoxigenic fungi in corn and other ingredients supplemented with Zn. These results suggest that stricter control of Zn levels during manufacture could reduce aflatoxin contamination of feed consumed by chickens.

Journal Article↗
PubMed1984

Method for detecting production of zearalenone, zearalenol, T-2 toxin, and deoxynivalenol by Fusarium isolates.

Three methods for detecting toxigenic fusaria in culture were compared by using known producers of zearalenone, zearalenol, T-2 toxin, and deoxynivalenol. Moist, autoclaved rice cultures of known toxigenic isolates grown in 20-ml tubes yielded oily extracts containing compounds which interfered with qualitative and quantitative analysis for the mycotoxins. Vermiculite moistened with nutrient broth in 20-ml tubes yielded a much cleaner extract. Growing the fungi on a liquid medium required a shorter incubation period, but yields of T-2 toxin and deoxynivalenol were low and variable, and the method required greater space in the incubator. Screening of the extracts by thin-layer chromatography with colorimetric spray reagents to detect the presence of these toxins permitted reduction in the number of extracts quantified by the more lengthy gas-liquid chromatographic method. Culturing in nutrient broth on vermiculite in tubes coupled to a qualitative screen before quantitation proved to be a convenient, inexpensive, and relatively rapid method that enabled reliable screening of a large number of Fusarium isolates for toxin production as compared with prior methods.

Culture Media↗
PubMed1984

Bioconversion of alpha-[14C]zearalenol and beta-[14C]zearalenol into [14C]zearalenone by Fusarium roseum 'Gibbosum'.

Cultures of Fusarium roseium 'Gibbosum' on rice were treated with [14C]zearalenone, alpha[14C]zearalenol, or beta-[14C]zearalenol to determine whether a precursor-product relationship exists among these closely related fungal metabolites. Culture extracts were purified by silica gel column chromatography and fractionated by high-pressure liquid chromatography, and the level of radioactivity was determined. Within 7 days, the beta-[14C]zearalenol was converted to zearalenone, and no residual beta-[14C]zearalenol was detectable. Most of the alpha-[14C]zearalenol added was also converted into zearalenone with 14 days. In cultures treated with [14C]zearalenone, no radioactivity was noted in any other components.

Carbon Radioisotopes↗
PubMed1984

Feed refusal during ochratoxicosis in turkeys.

Previous observations of feed refusal associated with apparent field outbreaks of ochratoxicosis in turkeys but not in chickens suggested that these species differed in response to ochratoxin or that different factors were involved in the field outbreaks. The recent development of laboratory models for the study of feed refusal syndromes in poultry permitted an evaluation of the problem. Pure ochratoxin A reduced the consumption of feed by young turkeys. Refusal of graded concentrations of ochratoxin A in feed was not detected in young chickens. These results, which suggested that feed refusal is a symptom of ochratoxicosis in turkeys but not in chickens, provide additional evidence that the aforementioned outbreaks were caused by ochratoxin and that ochratoxicosis is an emerging problem in the poultry industry.

Animals↗
PubMed1983

Models of feed refusal syndrome in poultry.

Research on feed refusal syndrome(s), an important problem in the poultry industry, has been hindered by a lack of sensitive and quantitative laboratory models. Suitable models were developed using five groups of 30-week-old male chickens per treatment. Feed or water, depending on which was to be measured, was withdrawn overnight. Then consumption of treated water or feed was measured over a 6-hr period of rehydration or refeeding. In aqueous solutions NaCl, H2SO4, and Na2CO3 reduced liquid consumption in a dose-related manner. Ammonia caused a similar refusal when added to feed. Consumption of feed and water was not influenced by pH over the ranges likely to occur as a result of fungal activity. Consumption of feed on a wet weight, but not dry weight, basis was influenced by the moisture content of feed. A culture filtrate of Fusarium roseum NRRL 1181 containing diacetoxyscirpenol, a trichothecene mycotoxin, reduced consumption of feed by about 77% when added to feed and reduced liquid consumption by about 92% when substituted for drinking water. Thus, the models for consumption of liquids and solids appear to have the attributes necessary for quantitative investigation into the relationships of mycotoxins to feed refusal syndromes.

Ammonia↗
PubMed1983

Mold inhibitory activity of an N-oxime ether.

A N-oxime ether (CG-97967), representative of a new class of mold inhibitors that have promising in vitro activity, was tested for activity in unaltered corn meal. Using inhibition of the production of respiratory CO2 as the criterion of antifungal activity, the N-oxime ether was equal or superior to propionic acid in three batches of corn meal. Further testing against pure cultures of fungi, yeast, and bacteria revealed that the experimental compound was unstable and was inactivated by heating, which caused an oxidative decarboxylation. These results suggest that use of the N-oxime ether would be inappropriate in pelleted poultry feed.

Animal Feed↗
PubMed1983

Survey of molds and mycotoxins for their ability to cause feed refusal in chickens.

The cause of feed refusal by poultry is an important problem that has not been established. T-2 toxin, a culture filtrate of Fusarium roseum NRRL 1181 containing a high concentration of diacetoxyscirpenol, and a filtrate of Penicillium citrinum containing an unknown factor produced refusal activity in week-old chickens. Citrinin stimulated water consumption while aflatoxin did not affect feed consumption. Detection of refusal activity was more sensitive when the refusal factor was presented in the drinking water than in the feed. The experimental model used here was sensitive, and, with appropriate controls, would appear suitable for the isolation and study of new factors capable of causing feed refusal in poultry.

Aflatoxins↗