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Biomedical subjects

H E Amos

Publications and source records attributed to H E Amos.

18 recordsLinked to original sources
PubMed1991

Effects of dietary fiber and feeding frequency on ruminal fermentation, digesta water-holding capacity, and fractional turnover of contents.

To determine the effects of different sources of fiber and feeding frequency on digesta water-holding capacity (WHC; g H2O/g DM) and ruminal liquid contents, four ruminally fistulated Jersey steers were fed a 60:40 roughage-concentrate diet at 1.5 times NEm. Diets contained either sorghum silage (SS) or a 67:33 mixture of SS and soyhulls (SH) as roughage and were fed either once or 12 times daily, in a 2 x 2 factorial experiment with 15-d periods. Ruminal fluid was sampled at 2, 4, 6, 8, 10, 12, 16, 20, and 24 h after a dose of Co-EDTA on d 10 and analyzed for Co, VFA, ammonia, buffering capacity, and osmolality. Ruminal WHC, NDF, ADF, lignin, and starch were measured in samples obtained by ruminal evacuation at 3, 6, 12, and 24 h after feeding on d 11, 12, 14, and 15, respectively. Substitution of SH for SS decreased ruminal pH .32 units and dilution rate by 26.8% but increased total VFA by 10.9%, osmolality by 13.6%, and the fractional turnover rate (FTR) of ADF by 22.5% (P less than .05). Frequent feeding resulted in 4.7, 21.9, and 74.4% increases in total VFA and FTR of ruminal DM and starch (P less than .05), respectively. Interactions (P less than .05) were observed between dietary fiber source and feeding frequency for ruminal fluid molar percentage acetate to propionate ratio (A/P), liquid volume (evacuated), and WHC (kilograms). Substituting SH for SS decreased ruminal WHC (kilograms), liquid volume, and A/P only in steers fed once daily. Ruminal WHC (kilograms) was correlated positively with ruminal liquid volume but negatively with DM FTR. The dynamics of digesta WHC (kilograms) associated with dietary fiber source and feeding frequency suggest that it may influence the contribution of water and salivary secretions to ruminal liquid contents.

Animal Feed↗
PubMed1991

Protein and fiber digestion by steers grazing winter annuals and supplemented with ruminal escape protein.

Six abomasally cannulated Hereford steers (12 mo of age, 300 +/- 10 kg) grazing annual ryegrass (Lolium multiflorum Lam.) paddocks were used in a replicated 3 x 3 Latin square design to determine effects of ruminal escape protein (EP) supplementation on forage intake, fiber digestion, and protein flow to the intestine. Steers were fed one of three isoenergetic supplements: high ruminal escape protein (HEP), low ruminal escape protein (LEP), or corn, which supplied an estimated .25, .125, or 0 kg of EP/d in addition to EP supplied by corn. Fish meal (FM) and distiller's dried grains with solubles (DDGS) were sources of EP; FM provided 66.7% and DDGS provided 33.3% of estimated EP. Steers were adjusted to each supplement for 7 d before a 4-d collection period. Both total and forage DMI responded quadratically (P less than .03 and P less than .07, respectively) to EP supplementation. Total tract DM digestion tended (P less than .13) to increase linearly with EP supplementation. Abomasal total CP flow increased linearly (P less than .10) as supplemental EP increased. Crude protein flow in steers receiving HEP, LEP, and corn was 1,137, 1,027, and 844 g/d, respectively. Likewise, abomasal nonammonia N (NAN) tended to be greater (P less than .15, linear) for steers receiving HEP. Nonammonia N flows were 1,044, 955, and 771 g/d for steers receiving HEP, LEP, and corn, respectively. Abomasal ammonia flow did not differ (P less than .20) among treatments, nor did reticuloruminal fiber digestion (P less than .20). These data indicate that EP can increase postruminal protein flow and will not negatively affect fiber digestion in steers grazing annual ryegrass pastures.

Animal Feed↗
PubMed1991

Ruminal escape protein supplementation and zeranol implantation effects on performance of steers grazing winter annuals.

Fifty-four crossbred steers (275 kg) were assigned randomly to one of three isoenergetic but not isonitrogenous ruminal escape protein (EP) supplements: high ruminal escape protein (HEP), low ruminal escape protein (LEP), or corn. The supplements contained corn, distillers' dried grains with solubles (DDGS), and fish meal. Supplements were fed at approximately 1.5 kg/d; the HEP and LEP supplements provided .25 and .12 kg more EP per day than corn, respectively. These supplements also supplied .20 and .10 kg more CP per day than corn. Fish meal and DDGS provided 66.7 and 33.3% of the supplemental EP, respectively. One-half of the steers in each supplement treatment were implanted once with 36 mg of zeranol. Steers grazed wheat (Triticum aestivum L.)-annual ryegrass (Lolium multiflorum Lam.) pastures for 73 d (March 1 to May 12). Daily gains (kg/d) increased linearly (P less than .07) as EP increased (HEP, 1.61; LEP, 1.54; corn, 1.47); responses were apparent only during the later periods as forage quality declined. Zeranol implants increased (P less than .02) ADG (kg/d) by 9.7% (1.58 vs 1.44). After grazing, all cattle were fed a finishing ration for 76 d. Pre-feedlot EP level produced a negative linear (P less than .04) response on feedlot ADG (kg/d) (HEP, 1.44; LEP, 1.50; corn, 1.59). Zeranol implantation during the grazing phase did not affect (P greater than .2) performance during the feedlot phase or carcass characteristics other than increased ribeye area (P less than .08). Compensatory feedlot performance negated all weight gain advantages elicited by EP supplementation during the grazing period.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1991

Dietary fat, protein degradability, and calving season: effects on nutrient use and performance of early lactation cows.

Twelve multiparous Holstein cows calving in fall and 12 calving in summer were blocked into four groups and used in a 2 x 2 x 2 factorial to determine the effects of season of calving, dietary fat, and protein degradability on milk production and efficiency of NEL utilization in a 16-wk study. Blocks were assigned randomly to one of four dietary treatment combinations: 1) control concentrate plus soybean meal (high degradability protein supplement); 2) control concentrate plus a mixture of heated soybean meal and corn gluten meal (low degradability protein supplement); 3) a blend of the control concentrate and a concentrate containing 12.1% fat to provide 1 kg d-1 fat, plus soybean meal; and 4) concentrate as in diet 3 plus heated soybean meal and corn gluten meal. Nutrient intake, milk yield and composition, BW changes, and daily ambient temperature were monitored. Intake of DM appeared to be related to NDF intake but was not affected by fat, protein degradability, or calving season. Intake of NEL was increased by feeding fat. Digestabilities of DM and CP were increased and fiber was decreased by feeding fat. Percentage and yields of milk fat, SNF, and protein and 4% FCM production were higher in cows calving in fall. Milk fat percentage was low in all cows in the study. Efficiency of energy utilization for milk production was decreased in cows fed fat and calving in the summer and by low protein degradability during wk 5 to 8 of lactation. At high concentrate intake, calving season had more effect on milk production than level of fat or protein degradability.

Animal Feed↗
PubMed1979

Immunological aspects of practolol toxicity.

It is unfortunate that there is conflicting immunological data relating to the practolol syndrome. It has not been established if "practolol patients" have some altered T cell function. The work of Behan et al. (1976) strongly supports this interpretation but other groups have not come to the same conclusion. The role of the antibody specific for a practolol metabolite needs to be determined. In practice this is going to be very difficult to do; the drug is no longer used and patients, for obvious reaons, are unwilling to take part in clinical experiments. It is likely that the nature of the metabolite will eventiually be defined and it would be a significant step forward if it could be shown that the antigenic determinant was not formed by other structurally related beta-blocking drugs. Meanwhile the stimulus to further research must be to produce an animal model system, but, for various political and economic reasons, support for such a research effort is difficult to justify.

Animals↗
PubMed1979

The distribution of 2,4-dinitrophenyl groups in lymphoid tissue of guinea-pigs following skin painting with 2,4-dinitrochlorobenzene.

Cellular localization of 2,4-dinitrophenyl (DNP) groups in the peripheral lymphoid system of guinea-pigs was studied at various times after painting the skin with 2,4-dinitrochlorobenzene (DNCB) by the immunofluorescent method using anti-DNP antibody. The cells taking up the stain (DNP cells) were shown to be mainly lymphocytes. At 1-6 h after painting the majority of DNP cells were found in the peripheral blood and the spleen but the maximum number was reached in the lymph node draining the site of DNCB application 12 h after painting. Injecting cyclophosphamide (CY) 3 days before painting with DNCB, heightened the number of DNP cells residing in the draining node. The animals treated with the tolerogen, 2,4-dinitrobenzene sulphonic acid sodium salt (DNBSO3Na), and then painted with DNCB, had fewer DNP cells than those animals which had simply been painted once with DNCB. The culture supernatants prepared from the draining nodes of both normal and tolerant animals partially blocked the anti-DNP antibody binding with DNP cells. It is suggested that the cells associated with DNP groups residing in the draining lymph node act as immunogens in the immunizing process of contact sensitivity.

Administration, Topical↗
PubMed1978

Possible role of antibody specific for a practolol metabolite in the pathogenesis of oculomucocutaneous syndrome.

The clinical distribution of an antibody to a metabolite of practolol was investigated, particularly in relation to the oculomucocutaneous syndrome. Serum samples were obtained from patients with and without a history of adverse reaction to practolol and two groups of control patients who had never taken the drug. Five patients also participated in a challenge study. The presence of the antibody was found to be related to practolol administration, and antibody activity could be increased by antigenic challenge. The role of this antibody in the pathogenesis of the oculomucocutaneous syndrome remains uncertain. The lesions may be the result of a hitherto unknown type of hypersensitivity response to practolol.

Antibodies↗
PubMed1977

Allergic drug reactions: an in vitro model using a mixed function oxidase complex to demonstrate antibodies with specificity for a practolol metabolite.

Reactive metabolite products of the drug practolol were generated in vitro using the rat liver mixed function oxidase complex. The metabolites were spontaneously coupled to a non-agglutinating rabbit antibody to human O red blood cells, so forming a metabolite-antibody reagent. This reagent was then used to passively sensitize human O red cells which subsequently acted as indicator cells for detecting anti-metabolite antibodies.

Animals↗
PubMed1975

Untoward effects associated with practolol: demonstration of antibody binding to epithelial tissue.

An antibody which sticks to the intercellular region of xenogenic epidermal tissue has been shown by indirect immunofluorescence to be present in the serum of patients with practolol-induced eye damage. These antibodies and those found in patients with pemphigus were compared for their ability to bind to isolated epidermal cells. Binding was achieved only with the pemphigus antibody, which suggests that it may have a different specificity from the antibody associated with practolol-induced eye damage.

Animals↗
PubMed1975

Methionine replacement value of N-acetylmethionine and homocysteinethiolactone hydrochloride for growing rats.

The ability of young growing rats to absorb DL-homocysteinethiolactone hydrochloride (HCTL-HCl) and N-acetyl-DL-methionine (NAM) and to use them for growth when fed a methionine-deficient diet was studied. In situ intestinal absorption studies demonstrated that both compounds are readily absorbed. Intestinal half-times were 24 minutes for NDTL-HCl and 44 minutes for NAM. Adding molar equivalents of 0.2 or 0.4% methionine to a 0.2% methionine basal diet fed ad libitum resulted in 28-day gains that were 83.2 and 91.1%, respectively, for NCTL-HCl and 94.6 and 99.8% for NAM of the average gain resulting when DL-methionine was added at equivalent levels. Feed efficiencies were also significantly (P smaller than 0.05) improved over rats fed the basal diet. Increasing the HCTL-HCl addition to 0.6% reduced feed intake and gain but not feed efficiency.

Acetates↗
PubMed1975

Contact sensitivity in vitro. II. The effect of beryllium preparations on the proliferative responses of specifically allergised lymphocytes and normal lymphocytes stimulated with PHA.

Beryllium in various physical forms was studied for its ability to induce increased 14C-thymidine incorporation by allergised guinea pig lymphocytes. No increase was observed. It was further shown that beryllium had an inhibitory effect on the response of normal lymphocytes to PHA and on the response of allergised lymphocytes to antigen. These results support the finding in other systems that beryllium can suppress DNA synthesis.

Animals↗