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Biomedical subjects

P B Hamilton

Publications and source records attributed to P B Hamilton.

At least 109 records · Page 6Linked to original sources
PubMed1976

A computerized system for storage and statistical analysis of clinical amino acid data.

We have developed a system of computer programs to expedite analyses of amino acid data obtained in a clinical environment. The system contains a program for building and maintaining libraries of chromatogram data, and a program for retrieval of data on the basis of any of its associated biographical characteristics. Several programs have been written that work with data drawn from the libraries. They provide for easy presentation, manipulation, or statistical analysis of the data. Included are comparison of population means and variances and intra-population correlation analyses. A minicomputer that has 12K of core storage is adequate for use with the system.

Amino Acids↗
PubMed1976

Effect of broad and narrow spectrum fluorescent light on blood constituents.

Riboflavin in whole blood, G-6-PD activity in erythrocytes and amino acids in plasma of infants irradiated by broad and narrow spectrum blue fluorescent light were determined. Riboflavin was reduced by both types of light. Loss of G-6-PD activity during phototherapy with subsequent hemolysis was observed in some infants under each type of light source, both in vivo and in vitro. This phenomenon may be related to the indirect effect of riboflavin reduction and not to a direct effect upon the enzyme. The reduction of the plasma concentration of some amino acids observed under broad spectrum irradiation but not under pure blue light may not be of significance, but is of concern. These data indicate that all fluorescent light sources in current use for phototherapy produce biologic effects of importance beside the primary purpose of the treatment to reduce hyperbilirubinemia. It is apparent from the results of these studies that phototherapy light penetrates more deeply than the superficial skin to exert photochemical effects.

Amino Acids↗
PubMed1975

Egg production, shell thickness, and other physiological parameters of laying hens affected by T-2 toxin.

T-2 toxin has been reported to cause severe oral lesions and neural disturbances in young broiler chickens. T-2 toxin, when added at a level of 20 mug per g of feed, caused oral lesions but no abnormal neural disturbances in young broiler chickens. T-2 toxin, when added at a level of 20 mug per g of feed, caused oral lesions but no abnormal neural symptoms in laying hens. T-2 toxin had no effect on either hemoglobin, hematocrit values, erythrocyte count, plasma glucose, prothrombin times, or the sizes of the liver, spleen, pancreas, and heart. Lipid content of the liver was not altered. Feed consumption, however, was reduced, as were the total plasma protein and lipid concentrations and the total leukocyte count. Most important economically was the lowered egg production and a thinner egg shell. The timing and severity of the symptoms suggest that T-2 toxin causes primary oral lesions that reduce feed consumption with a consequent reduction in serum proteins and lipids, which culminate in decreased egg production. The leucopenia and thinner egg shell may be independent systemic effects of T-2 toxin in laying hens.

Animals↗
PubMed1975

Nephrotoxicity of dietary ochratoxin A in broiler chickens.

Graded doses of pure ochratoxin A (0,0.5,1.0,2.0,4.0, and 8.0 mug of toxin per g of feed) were incorporated into a commercial diet which was fed to chicks from 1 day to 3 weeks of age, at which time the experiments were terminated. Growth was inhibited at 2.0 4,0, and 8.0 mug/g, whereas the kidneys were enlarged at doses of 1.0 mug/g and above. Renal function as measured by clearance of phenol red was decreased 15 and 31% by doses of 4.0 and 8.0 mug/g, respectively. Uric acid was increased 38 and 48% over the control values by doses of 4.0 and 8.0 mug/g, respectively. The plasma electrolytes Na, Cl,Ca, and K were measured; however, only K was significantly ( P smaller than 0.05) altered, showing a decrease at doses of 4.0 and 8.0 mug/g. The percentage dry weight of the kidneys decreased significantly at dose levels of 4.0 and 8.0 mug/g, indicative of edema. Histological examination of kidney sections gave the impression of edema and some tubular necrosis. Pathological changes were observed at all dose levels. These data demonstrate that ochratoxin A is a severe nephrotoxin in young broiler chickens.

Animal Feed↗
PubMed1975

Liver lipid content of twenty varieties of laying hens from three confinement systems.

Average liver lipid values were determined for 20 varieties of 71-week old laying hens managed in 3 confinement systems of the 1972-73 North Carolina Random Sample Laying Test. There were highly significant differences in liver lipid atrributable to variety, to confinement system, and a significant variety X system interaction. Four varieties had consistently high and five had consistently low liver lipid values in all 3 confinement systems. Varietymeans ranged from 25.8 to 49.0% liver lipid on a dry weight basis. Hens confined 2/cage had slight but significantly higher liver lipid than hens 7/cage or in floor pens. Liver lipid was positively correlated with body weight in hens 2/cage and in floor pens. There were no significant correlations of liver lipid with egg production or mortality. A frequency distribution of individual liver lipid values revealed a continuous distribution from 15.4 to 65.4with a pronounced skew to the right of the mean of 38.2%. Neither a fatty liver syndrome nor liver hemorrhage syndrome was reported for any of the flocks during the laying year. The normal range of liver lipid values for hens 71 weeks of age appears to be between 25 and 49 g. of lipid per 100 g. of dry liver weight.

Animals↗
PubMed1975

Investigation and standardization of prothrombin times in chickens.

This investigation was undertaken to standardize the determination of the one-stage prothrombin time for use with chickens. Homologous thromboplastin was essential and the most active thromboplastin was obtained from chickens four-weeks old or younger. Acetone-dried brain powder could be stored for at least 4 months at -15 degrees C. without loss of activity. Extraction of brain powder with 0.025 M CaCl2 at 42 degrees C. gave better thromboplastic activity than the standard extraction with physiological saline at room temperature. Thromboplastin solutions could be stored in ice water for only 6 hours without loss of activity. Citrate concentration had to be increased from the usual 0.10 M to 0.18 M to prevent premature clotting of plasma. Plasma donor age had no effect on the prothrombin times. Freezing and thawing as well as storage of plasma in the frozen state increased the prothrombin times. Using the best conditions, the mean prothrombin time for 1200 birds determined over a 6-month period was 9.4 sec. with an individual range of 7.18-11.4 sec. This represents a significantly lower prothrombin time with lower variability than that reported in the literature.

Age Factors↗
PubMed1975

Altered feathering of chicks caused by T-2 toxin.

Dietary T-2 toxin (0, 1, 2, 4, 8, and 16 mug./g.) was fed to 4 groups of 10 chickens at each treatment level from hatching until 3 weeks of age. Growth inhibitory levels (4, 8, and 16 mug./g.) caused abnormal feathering which appeared dose related. The chickens were sparsely covered with short feathers protruding at odd angles in comparison to controls. There were few feathers on the base of the neck, on the anterior dorsal surface of the wing, and on the side and back adjacent to the tail. Feather tips frequently were constricted and bent downward while the quill could have a reverse curve. A literature survey suggests that T-2 toxin may cause this effect through a nutritional imbalance.

Animals↗
PubMed1975

Interaction of aflatoxicosis with heat stress.

An earlier study reported an increased resistance of chickens to an acute lethal heating episode (43 degrees C. and 45% relative humidity) during aflatoxicosis. This varies from other stresses investigated which interact with aflatoxicosis to make chickens more sensitive to the stress factor. The effects of graded doses of dietary aflatoxin (0, 0.625, 2.5, 5.0, and 10.0 mug./g.) on the body temperature, on body fat, on the serum glucose, and on the effect of varying the severity of the heat stress were measured. Both serum glucose and total body fat were decreased significantly (P less than 0.05) by doses of 2.5 mug./g. and above. Cloacal temperature was decreased slightly but significantly (P less than 0.05) in chickens fed 5 or 10 mug./g. for 12 days or longer. The mean survival time of birds exposed to a heat stress of 40 degrees C. and 45% relative humidity did not vary with the dose of aflatoxin while a milder stress of 37 degrees C. and 45% relative humidity caused chickens fed aflatoxin at 2.5 mug./g. or above to show decreased survival times (P less than 0.05) in comparison to the controls. These data can be rationalized by assuming that the lessened burden of body fat during aflatoxicosis accounts for the increased survival time in a severe (43 degrees C. and 45% relative humidity) heat stress but that other parameters related to physiological stress play a dominant role during a less severe but more prolonged heating episode. It seems likely that the hypoglycemia, hypothermia, and lessened body fat also account for the previously reported increased sensitivity to a lethal cold exposure during aflatoxicosis.

Adipose Tissue↗
PubMed1975

Decreased plasma carotenoids during ochratoxicosis.

Two field cases of underpigmented broilers were reported; investigation revealed the presence of ochratoxin but not aflatoxin. A laboratory experiment revealed that dietary ochratoxin A at levels of 4.0 and 8.0 mug./g. lowered significantly (P less than 0.05) the concentration of plasma carotenoids which are an accepted indicator of carcass pigmentation.

Animals↗
PubMed1975

Interaction of aflatoxin and paratyphoid infections in broiler chickens.

There was a significant (P less than 0.05) interaction resulting in increased mortality in chickens fed aflatoxin and infected with Salmonella worthington, S. thompson, S. derby, or S. typhimurium var. copenhagen which cause paratyphoid. There was no interaction on body weight or spleen weight; however, there wan an interaction with all four Salmonella species resulting in enlarged livers from which Salmonella could be isolated with increased frequency. Aflatoxin caused a decrease in total serum proteins but a dramatic increase in anti-Salmonella agglutinins in infected birds. These results suggest that aflatoxin impairs some component of the immune system other than that forming humoral antibodies and perhaps other than the reticuloendothelial system which have been reported previously to be impaired during aflatoxicosis in the chicken.

Aflatoxins↗
PubMed1975

The interaction of ochratoxin A with some environmental extremes.

Presently, ochratoxin is the most potent mycotoxin studied in chickens. The possibility that ochratoxin can interact with environmental extremes was investigated by incorporating pure ochratoxin A (0, 0.5, 1.0, 2.0, 4.0, and 8.0 mug./g. feed) into the diet of 4 replicates of 10 birds from hatching until 3 weeks of age. There was a significant (P less than 0.05) decrease in the mean survival times of birds exposed to 4 degrees C. and 90% relative humidity at dose levels of 4.0 and 8.0 mug./g. However, birds exposed to 43 degrees C. and 45% relative humidity had a significantly (P less than 0.05) prolonged mean survival time at 8.0 mug./g. Birds given drinking water containing 2% NaCl had a significant (P less than 0.05) decrease in mean survival time at 8.0 mug./g. These data suggest that ochratoxin like aflatoxin can interact with other agents to produce syndromes not attributable to each alone.

Animals↗
PubMed1975

Candida species and crop mycosis in broiler chickens.

A mycological survey of the crops of approximately 100 healthy birds from each of 6 grow-out operations revealed that the incidence of Candida in the crops ranged from 17.4 to 51.5% with a mean value of 32.3%. The population of Candida in the crops of birds found positive was of low magnitude in the majority of the chickens examined. Of the 573 birds examined in this study less than 1% exhibited visible lesions attributable to Candida. C. albicans comprised 95% of the isolates while C. ravautii, C. salmonicola, C. gulliermondi, C. papapsilosis, C. catenulata and C. brumptii comprised the remainder. The incidence and number of Candida in the crop was related apparently to management practices on the farm. The crops from four field outbreaks of crop mycosis were also studied. Three of the four cases of crop mycosis were characterized by multiple strains of C. albicans in the crop. In one case, C. parapsilosis also was isolated from the crop.

Animals↗
PubMed1975

Interaction of T-2 toxin with Salmonella infections of chickens.

A significant (P less than 0.05) interaction resulting in increased mortality occurred in chickens fed T-2 toxin (16 mug./g. of diet) and infected with either Salmonella worthington, S. thompson, S. derby, or S. typhimurium var. copenhagen, all species that cause paratyphoid. No interaction on growth rate or relative size of the bursa of Fabricus occurred, although T-2 toxin alone caused a significant (P less than 0.05) regression of that organ. The spleen size relative to the body weight was decreased (P less than 0.05) by T-2 toxin and increased (P less than 0.05) by the Salmonella infections. Interactions were observed on spleen size between the toxin and S. thompson (P less than 0.05) and S. derby (P less than 0.10). Total serum proteins were not affected by T-2 toxin or Salmonella infections. Agglutinins were formed in response to the infections, but the titers were unaltered by T-2 toxin.

Animals↗
PubMed1975

The anemia caused by aflatoxin.

The effects of graded doses of dietary aflatoxin (0, 0.625, 1.25, 2.5, 5.0, and 10.0 mug./g.) on hemoglobin, packed blood cell volume, erythrocyte count, leucocyte counts, bone marrow lipid, and bone marrow nucleic acids of chickens were measured. The hemoglobin, packed cell volume, and erythrocyte count were reduced significantly (P less than 0.05) to about the same extent by any given dose. Microscopic examination of stained smears of the bone marrow revealed a hyperplastic response including the granulocytic elements. Chemical analyses of the marrow revealed a decreased lipid content and an increased content of ribonucleic acid and deoxyribonucleic acid. Total leucocytes were increased about three fold by aflatoxin (10 mug./g). Differential leucocyte counts revealed that the heterophils were increased while the eosinophils were unaffected and the basophils, lymphocytes, and monocytes were decreased. The increase in nucleic acids of the marrow and in circulating leucocytes occurred with doses which inhibit growth rate. These data suggest that aflatoxin causes a hemolytic anemia in chickens, that aflatoxin, by itself, is not involved in the hemorrhagic anemia syndrome of chickens, and that aflatoxin does not cause in chickens a general inhibition of ribonucleic acid and protein synthesis as assumed from studies on rats.

Aflatoxins↗