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Biomedical subjects

A C Hammond

Publications and source records attributed to A C Hammond.

66 records · Page 4Linked to original sources
PubMed1984

Site of 3-methylindole and indole absorption in steers after ruminal administration of L-tryptophan.

To determine the site of 3-methylindole (3MI) and indole absorption in cattle after ruminal administration of L-tryptophan (TRP), 4 Holstein steers were given 0.4 g of TRP/kg of body weight directly into the rumen through ruminal cannulas. Chromium EDTA and ruthenium phenanthroline were added to feedings of orchard grass hay twice a day for measurement of fluid and particulate flow to the duodenum, respectively. Passage of 3MI and indole (products of ruminal fermentation of TRP) to the duodenum was determined by the products of digesta flow rate and concentration in duodenal contents. Ruminal fluid, duodenal contents, and jugular blood were sampled at postdosing hours (PDH) 0, 6, 12, 18, 24, 36, and 72 for analysis of 3MI, indole, and digesta flow markers. Ruminal, duodenal, and jugular plasma concentrations of 3MI and indole peaked at PDH 12 to 24 at 152.4 and 25.9; 15.5 and 1.0; and 8.7 and 2.2 mg/L, respectively. Most 3MI and indole reaching the duodenum were associated with the particulate phase of the digesta. On a molar basis, total passage of 3MI to the duodenum during 72 hours amounted to 1.0% of the TRP dose for 3MI and 0.1% of the TRP dose for indole. Absorption of 3MI and indole in these steers was almost entirely proximal to the duodenum.

Animals↗
PubMed1983

Net absorption of 3-methylindole and indole in cattle after oral administration of L-tryptophan.

The time course and quantity of 3-methylindole (3MI) and indole absorbed after oral administration of L-tryptophan (TRP) was determined in 2 steers. The relationship between the appearance of 3MI and indole in the rumen and blood plasma to absorption of 3MI and indole was also studied. Two Hereford X Angus steers with portal vein, mesenteric vein, and femoral (steer 1) or iliac (steer 2) artery catheters were used. Absorption rates from the portal drained viscera (net absorption) of 3MI and indole were determined by the product of portal and arterial concentration difference and blood flow. Blood flow was determined by primed continuous infusion of p-aminohippuric acid into a mesenteric vein. Three absorption measurements 30 minutes apart were taken at midpoint times of 0, 12, 24, 36, and 48 hours after oral administration of 0.4 g of TRP/kg of body weight. Steer 1 was dosed twice resulting in a total of 45 absorption measurements. Net absorption of 3MI and indole peaked at an average of 1.05 and 0.81 g/hr, respectively. By 48 hours, 29.2% and 15.3% of the TRP dose were accounted for by 3MI and indole absorption, respectively. Closed system in vitro incubations of TRP with ruminal fluid from the same 2 steers resulted in a TRP to 3MI conversion of 23.2% and a TRP to indole conversion of 10.7%. Net absorption of 3MI and indole closely followed and was correlated with concentration of 3MI and indole in ruminal fluid and blood plasma.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗
PubMed1980

Indole toxicity in cattle.

Indole and 3-methylindole (3MI) are ruminal metabolites of L-tryptophan (TRP) and have similar physical and chemical properties. 3-Methylindole causes acute bovine pulmonary emphysema (ABPE). The effects of indole when administered orally to cows were determined. Four mature Holstein cows were given increasing doses of 0.05, 0.1 and 0.2 g indole per kg body-weight orally at two-week intervals. The animals were killed one week after the last dose. Plasma indole concentrations peaked three house after administration at 4.5, 8.8 and 19.8 microgram per ml after the 0.05, 0.1 and 0.2 doses, respectively. Detectable concentrations of indole (more than 0.02 microgram per ml) persisted in the plasma from three to 25 hours after dosing. Packed cell volume was decreased (P less than 0.01) at 48 and 72 hours after the 0.2 g per kg dose and at 72 hours after the 0.1 g per kg dose. Plasma haemoglobin was increased (P less than 0.05) at 48 hours after the 0.2 and 0.1 g per kg doses. By 72 hours after the 0.2 g per kg dose, all cows had mild diarrhoea and haemolysis and two of the cows had haemoglobinuria. At necropsy, microscopic lesions of haemoglobinuric nephrosis were seen in all four cows. No lesions of ABPE were found in any of the animals.

Animals↗
PubMed1980

Prevention of tryptophan-induced acute bovine pulmonary oedema and emphysema (fog fever).

The pathogenesis of acute bovine pulmonary oedema and emphysema (ABPE) is related to the ruminal formation of 3-methylindole (3MI) from L-tryptophan (TRP), a naturally occurring amino acid and constituent of forage. The objectives of the present study were to determine whether monensin and lasalocid, both polyether antibiotics, were effective in reducing ruminal conversion of TRP to 3MI in vivo and to confirm that reduction in ruminal conversion of TRP to 3MI prevented tryptophan induced ABPE. Sixteen mature Hereford cows were assigned to one of four groups and given TRP to induce ABPE. Group 1 was given 100 mg monensin orally twice daily starting one day before and ending four days after TRP dosing. Group 2 was given 200 mg monensin once daily and group 3 was given 100 mg lasalocid twice daily. Group 4, the control, was given only TRP without further treatment. All control cows developed clinical signs of respiratory disease and lesions of ABPE; one control cow died of ABPE. Mean ruminal 3MI concentrations in control cows reached a peak of 36.4 micrograms per ml. Clinical signs of pulmonary disease appeared in two cows treated with lasalocid and one died. Mean ruminal 3MI in these animals peaked at 38.8 micrograms per ml. No clinical signs of respiratory disease were observed in any of the monensin treated cows and at necropsy there were no pulmonary lesions of ABPE. Mean ruminal 3MI concentrations in monensin treated cows did not exceed 8.9 micrograms per ml. In all groups plasma 3MI concentrations generally reflected ruminal 3MI concentrations but at lower concentrations. The results of this experiment demonstrate that reduction in ruminal 3MI formation by monensin prevents tryptophan induced ABPE.

Animals↗
PubMed1980

Inhibition of ruminal degradation of L-tryptophan to 3-methylindole, in vitro.

Available evidence supports the view that acute bovine pulmonary edema and emphysema (ABPE) is related to ruminal production of 3-methylindole (3MI) from L-tryptophan (TRP). Ruminal production of 3MI is a two-step process involving the conversion of TRP to indoleacetic acid (IAA) followed by decarboxylation of IAA and 3MI. Reduction in ruminal 2MI production by the inhibition of either of these processes may prevent the onset of ABPE. A closed-system, in vitro ruminal fermentation technique was used to screen 27 compounds for their ability to reduce the conversion of TRP to 3MI. Several compounds tended to reduce 3MI production at both 25 and 5 micrograms/ml. Desoxysalinomycin, X-206, chloral hydrate, nigericin, lasalocid, monensin, narasin and salinomycin all reduced 3MI production by more than 80% at 5 micrograms/ml without reducing total VFA production. All of these compounds, except chloral hydrate, are polyether antibiotics. At least part of the inhibition due to monensin and narasin occurs at the level of TRP conversion to IAA.

Animals↗
PubMed1978

Monensin and the prevention of tryptophan-induced acute bovine pulmonary edema and emphysema.

3-Methylindole, a ruminal fermentation product of tryptophan, induces acute pulmonary edema and emphysema in cattle, and 3-methylindole is present in the ruminal fluid and blood of cows with a natually occurring form of this disease. Monensin, a polyether antibiotic and widely used feed additive for beef cattle, prevented tryptophan-induced acute bovine pulmonary edema and emphysema. Monensin acted by reducing the ruminal conversion of L-tryptophan to 3-methylindole both in vitro and in vivo. Lasalocid, also a polyether antibiotic, showed similar effects in vitro. These results provide a promising approach to prevention of this major respiratory disease of cattle.

Animals↗