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Biomedical subjects

R M Hamilton

Publications and source records attributed to R M Hamilton.

At least 55 records · Page 3Linked to original sources
PubMed1984

Feeding trials with vomitoxin (deoxynivalenol)-contaminated wheat: effects on swine, poultry, and dairy cattle.

Nutritional and toxicologic feeding trials with 3 species of farm animals demonstrated that decreased feed consumption and reduced weight gains in pigs are the main effects of ingestion of a diet with low vomitoxin (deoxynivalenol; DON) content, eg, 2 mg of DON/kg of feed, ie, 2 ppm. The feeding trials indicated that swine can ingest up to 2 mg of DON/kg of feed without serious adverse effects. Poultry can tolerate at least 5 mg of DON/kg feed. In fact, at concentrations up to 5 mg of DON/kg feed, some beneficial effects on poultry were observed. In dairy cattle, feed consumption decreased slightly when a wheat-oats diet containing 6 mg of DON/kg was fed at the rate of 1% of body weight/day, with hay offered ad libitum. In surveys of Canadian grains carried out during the past 3 years, the DON content (maximum of 8.5 mg/kg) in eastern Canadian wheats probably was not high enough to account for reports of feed refusal, vomiting, and reproductive problems in livestock operations. This conclusion is based partly on the fact that even at the highest concentrations of DON found in wheat, formulated diets comprise, at maximum, about 70% to 80% wheat. Consequently, the actual DON content of diets fed to farm animals would be much lower.

Animal Feed↗
PubMed1984

The hemi-monobloc.

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Activator Appliances↗
PubMed1983

Liver lipid levels in White Leghorn hens fed diets that contained wheat contaminated by deoxynivalenol (vomitoxin).

Three genotypes of White Leghorn hens were fed diets containing either clean wheat (less than .02 ppm deoxynivalenol in diet) or deoxynivalenol (vomitoxin) contaminated wheat (.35 or .70 ppm deoxynivalenol in diet) for 86 or 135 days. Lipid analyses indicated that the percent total lipid and the triglyceride content of livers from birds receiving the vomitoxin contaminated diets were significantly higher than for birds receiving the clean diet. However, the livers of birds receiving the .35 ppm diet had the highest percent total lipid and triglycerides. Livers from control birds contained 11.5% total lipid with 420 mg triglyceride per liver; livers from the .35 ppm birds had 16.7% total lipid, 785 mg triglyceride; livers from the .70 ppm birds had 13.4% total lipid, 548 mg triglyceride. Liver phospholipid content did not appear to be affected by the deoxynivalenol content of the diet. Both genotype and level of vomitoxin in the diet significantly affected liver cholesterol levels.

Animals↗
PubMed1983

Survey of vomitoxin contamination of 1980 Ontario white winter wheat crop: results of survey and feeding trials.

During the harvesting of the 1980 Ontario white winter wheat crop, producers noticed pink discoloration on kernels; this was attributed to Fusarium mold. Grain elevator and boatload samples were analyzed for mycotoxin contamination. Vomitoxin levels up to 8 ppm were detected in samples from southwestern Ontario. Other suspected mycotoxins were either nondetectable or present in trace amounts. Fusarium-contaminated wheat and clean wheat were added to swine and poultry diets for feeding trials. Feed refusal and decreased weight gains were observed in pigs fed diets containing 0.3 and 0.7 ppm vomitoxin, but there was no vomiting or other ill effects. Adult roosters and laying hens fed diets containing vomitoxin levels similar to those of the pig diets did not show any overt toxicological effects. Chemical analysis of suspected field cases of vomitoxin-contaminated feed did not reveal high vomitoxin levels.

Animal Feed↗
PubMed1981

Relationships between levels of essential fatty acids and zinc in plasma of cystic fibrosis patients.

Possible relationships between zinc and essential fatty acid metabolism have been assessed using plasma samples obtained from 39 cystic fibrosis patients. The fatty acid composition of plasma phospholipids was analyzed by capillary gas liquid chromatography and zinc levels were measured by atomic absorption spectrometry. Computer analyses revealed positive correlations between zinc levels and (a) arachidonic acid (p less than 0.001), (b) the arachidonate/linoleate ratio (p less than 0.02), and (c) eicosatrienoic acid (n-6) (p less than 0.001). These observations suggest that conversion of linoleate to arachidonate may be modulated by zinc.

Adolescent↗
PubMed1981

Replacement of riboflavin by an analogue in the blue-light photoreceptor of Phycomyces.

Under suitable conditions, roseoflavin [7-methyl-8-dimethylamino-10-(1'-D-ribityl)isoalloxazine] replaces riboflavin to about 80% in the photoreceptor of Phycomyces. The substitute-bearing photoreceptor functions with an efficiency of about 0.1% of that of the normal receptor. The substitution is proven by (i) a decrease of the effective light flux by a factor of 4.7, expressed as a corresponding increase in threshold, and (ii) an increase of the effectiveness of 529-nm light relative to 380-nm light. It has also been shown that roseoflavin is taken up by the mycelium, translocated to the sporangiophore, and effectively phosphorylated by the riboflavin kinase of Phycomyces.

Journal Article↗
PubMed1978

Dietary fiber and cholesterol metabolism in rabbits and rats.

Rabbits fed semipurified diets have elevated plasma cholesterol levels, and they oxidize [26-14C]cholesterol to expired 14CO2 more slowly than rabbits on a natural ingredient diet. Addition of several different types of fibrous material to a semipurified diet failed to prevent the hypercholesterolemic response. Rats on semipurified diets also oxidized [26-14C]cholesterol more slowly and tended to have somewhat higher plasma cholesterol levels than rats on commercial feed. Cholesterol oxidation was not stimulated by addition of fibrous materials to the semipurified diet, but rats fed a semipurified diet containing raw potato starch oxidized cholesterol at a rate comparable to that of rats on commercial diet. Raw potato starch was poorly digested by the rats. Cooked potato starch was well digested and failed to stimulate the rate of oxidation of cholesterol. A semipurified diet containing raw potato starch did not produce a hypercholesterolemic response in rabbits, even though the raw starch was well digested.

Animal Feed↗
PubMed1978

Intravenous cannulation of hens for long-term infusion.

Intravenous cannulation was performed on the brachial vein of the hen. The cannulation system consisted of a jacket that fitted around the body of the hen. An external sheath passed through the top of the cage, over a small pulley and was counter-weighted with lead. A subcutaneous polyethylene sheath was extended from the wing near the site of cannulation to the mid-point of the back between the wings and into the external sheath. Once the polyethylene cannula was inserted into and attached to the brachial vein, the free end was passed through the subcutaneous sheath, into and through the external sheath, and attached to a syringe or pump. No special post-cannulation care was necessary. The hens were housed in wire cages and received feed and water ad libitum. Twenty-four hens were continuously or intermittently infused for up to 73 days after cannulation.

Animals↗
PubMed1977

Plasma cholesterol levels in suckling and weaned kittens, puppies, and guinea pigs.

Plasma cholesterol levels in kittens and puppies were low at birth, rose during the suckling period, and then decreased at about the time of weaning. The increase during the suckling period was much greater in puppies than in kittens. No significant differences in plasma cholesterol levels were observed in puppies fed two different types of diet, horse meat or dog chow, after weaning. Guinea pigs had lower plasma cholesterols than either kittens or puppies. The level was highest on the first day after birth, decreased during the next 3 wk, and then remained fairly constant after the animals were weaned.

Aging↗
PubMed1977

The effect of dietary phosphorus level and strain of bird on the apparent metabolizable energy content of a laying hen diet.

An experiment was made in which laying hen diets containing four different levels of dicalcium were each fed to two replicate groups of 10 strains of S.C.W.L. hens. The apparent metabolizable energy (A.M.E.) values of the diets were measured. There was a small but significant (P less than 0.01) linear increase in the dietary A.M.E. value associated with decreasing levels of phosphorus. The A.M.E. values did not differ between strains of birds (P greater than 0.05) and there was no phosphorus level x strain interaction (P greater than 0.05).

Animal Feed↗
PubMed1976

Ion binding by X-537A. Equilibrium and rate of complexation of Co(2+) in methanol.

The reaction of X-537A (XH) with Co(2+) in methanol to form the complex CoX(+) has been studied fluorometrically to determine the equilibrium constant as a function of temperature. The effect of complexation on the proton NMR spectrum of the X-537A was studied to determine the kinetics of complex formation. Comparing the data for the reaction XM(+) leads to X(-) + M(2+) in methanol at 25 degrees for several M(2+) we find that the equilibrium constants increase in the order CoX(+) less than MnX(+) and span only a factor of 5 while the rate constants increase in the order NiX(+) less than CoX(+) less than MnX(+) and span a factor of more than 100.

Anti-Bacterial Agents↗
PubMed1976

Effects of diet on catabolism and excretion of (26-14C)cholesterol in rats.

The catabolism and excretion of [26-14C]cholesterol was studied in rats on semisynthetic and commercial diets low in fat or containing 15% butter or corn oil. Rats on the low fat commercial diet oxidized the labeled cholesterol to 14CO2 at more than twice the rate of those on the semisynthetic diet. Fecal excretion of labeled lipid was also somewhat higher with the commercial diet. The added fats had little effect on rate of oxidation of cholesterol but dietary corn oil stimulated fecal excretion of labeled lipid. The rate of loss of labeled cholesterol through oxidation and excretion showed a positive correlation with cholesterol biosynthesis, as measured previously by acetate incorporation into cholesterol in rats on the same kinds of diet. A simple method for efficient trapping and counting of 14CO2 was developed, which facilitated measurement of low levels of 14CO2 in expired air. Estimation of bile acid production from the rate of oxidation of [26-14C]cholesterol to expired 14CO2 and the specific activity of plasma cholesterol gave somewhat higher values than those obtained by other methods. Possible reasons for this difference are discussed.

Animals↗