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Biomedical subjects

J R Carlson

Publications and source records attributed to J R Carlson.

At least 145 records · Page 8Linked to original sources
PubMed1981

Production of Skatole and para-Cresol by a Rumen Lactobacillus sp.

The objective of this study was to examine the substrate specificity of several ruminal strains of a Lactobacillus sp. which previously was shown to produce skatole (3-methylindole) by the decarboxylation of indoleacetic acid. A total of 13 compounds were tested for decarboxylase activity. The Lactobacillus strains produced p-cresol (4-methylphenol) by the decarboxylation of p-hydroxyphenylacetic acid, but did not produce either o-cresol or m-cresol from the corresponding hydroxyphenylacetic acid isomers. These strains also decarboxylated 5-hydroxyindoleacetic acid to 5-hydroxyskatole and 3,4-dihydroxyphenylacetic acid to methylcatechol. Skatole and p-cresol were produced in a 0.5:1 ratio, when indoleacetic acid and p-hydroxyphenylacetic acid were combined in equimolar concentrations. Competition studies with indoleacetic acid and p-hydroxyphenylacetic acid suggested that two different decarboxylating enzymes are involved in the production of skatole and p-cresol by these strains. This is the first demonstration of both skatole production and p-cresol production by a single bacterium.

Journal Article↗
PubMed1981

Selenomonas sputigena septicemia.

Selenomonas sputigena is a curved motile anaerobic gram-negative rod that is a part of the normal upper respiratory tract of man. We present a case of speticemia associated with this organism and believe it to be the first such report describing systemic disease.

Bacteria↗
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

A method for controlling body wall turgor during electrophysiological recording from central neurons in ecdysing insects.

A method for obtaining intracellular recordings from central neurons of insects during the performance of ecdysial behaviors is described. Body wall turgor must be restored to high levels in order to provide the CNS with appropriate sensory feedback required for the generation of motor output. This is accomplished by installing the insect in a decompression chamber so that an opening in the animal's ventral surface communicates with the atmosphere. Reduction of chamber pressure causes expansion of the insect's body wall. It is suggested that adaptations of this technique to invertebrates with hydrostatic skeletons is possible and would permit electrophysiological studies of behaviors which normally require high blood pressures for their performance.

Animals↗
PubMed1980

Tissue and subcellular distribution and excretion of 3-[14C]methylindole in rabbits after intratracheal infusion.

The tissue and subcellular distribution and urinary excretion pattern of radioactivity in rabbits after intratracheal administration of a 14C-labeled pulmonary toxin, 3-methylindole (3MI), was studied. Approximately 40% of the administered radioactivity appeared in the urine within 1 h but none of the radioactivity in the urine was 3MI. The lung had a higher concentration of radioactivity than the liver. Other tissues with significant radioactivity were bile, fat, kidney, and plasma. Liver had the highest total content of radioactivity due to the size of the organ. More than 80% of the total radioactivity per gram of tissue was concentrated in the nuclear and microsomal fractions of lung whereas the soluble cell fraction of liver and kidney contained approximately 60% of the radioactivity. The mitochondrial fraction in lung, liver, and kidney was consistently low in radioactivity. The lung contained significantly more residual radioactivity 4 h after dosing compared with other tissues and the elevated radioactivity persisted for 3 days. The study indicated that [14C]3MI is rapidly absorbed from the lung tissue and metabolized by the animal before being excreted in the urine. The accumulation of radioactivity in lung microsomes may be related to the metabolism of 3MI.

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↗
PubMed1980

Ultrastructural pulmonary changes induced by intravenously administered 3-methylindole in goats.

Transmission electron microscopy was used to characterize early pulmonary lesions in goats after a 2-hour intravenous infusion of 0.04 g 3-methylindole (3MI) per kilogram body weight. Groups of 2 or 3 goats were euthanized at 0.5, 2, 4, 8, and 24 hours after the beginning of the infusion. Changes in lung ultrastructure were compared to noninfused and carrier-infused (propylene glycol) controls. By 0.5 hour, mitochondria and intracellular vesicles were swollen in capillary endothelial, alveolar, and nonciliated bronchiolar epithelial cells. Morphologic changes were most severe in the alveolar Type 1 and nonciliated bronchiolar epithelial cells. Interalveolar septums were swollen at 0.5 hour, and interstitial edema was severe at 2 hours. Denuded alveolar epithelial basement membranes were also observed at 2 hours, and some endothelial cells appeared dark and necrotic. Endothelial cells appeared normal after 2 hours. By 4 hours, the remaining intact alveolar Type 1 cells contained larger and more prominent clusters of smooth endoplasmic reticulum, compared with controls. Morphologic changes in alveolar Type 1 and nonciliated bronchiolar epithelial cells became progressively more severe during the 24-hour experiment. These findings demonstrate that 3MI induces a rapid cytotoxic effect primarily on alveolar Type 1 and nonciliated bronchiolar epithelial cells. Proliferation of smooth endoplasmic reticulum in these cells suggests involvement of the mixed function oxidase system in 3MI-induced pneumotoxicity.

Animals↗
PubMed1979

Modified coagglutination procedure for the serological grouping of streptococci.

Cowan I staphylococci coated with antisera to streptococcal groups A, B, C, D, F, and G were used as coagglutination reagents in a modified coagglutination procedure (MCAP). Streptococcal group antigens were extracted with a Streptomyces albus-lysozyme enzyme mixture for 30 min at 55 degrees C and centrifuged, and the supernatant was tested by slide coagglutination. Positive coagglutination reactions occurred within 30 s. The cell pellets from overnight broth cultures and colonies taken directly from sheep blood agar plates were tested and compared with the results of the Lancefield capillary precipitin method. Of the 102 strains of broth-grown cells tested, 100 were grouped by the MCAP and the Lancefield capillary precipitin method. The remaining two isolates were serologically identified only by the MCAP. Of the original 102 strains, 97 were tested by MCAP after extraction of five well-isolated colonies from a sheep blood agar plate. When this latter method was used, 95.9% of the strains were correctly identified. Nonspecific reactions were observed only while testing the MCAP with the direct plate assay. These cross-reactions were remedied promptly by either absorption or dilution of the antisera involved. The MCAP was found to be a rapid and reliable technique for the serological grouping of streptococci.

Agglutination Tests↗
PubMed1979

Role of mixed-function oxidase in 3-methylindole-induced acute pulmonary edema in goats.

The relationship between the pulmonary toxicity of 3- methylindole (3MI, skatole) and the mixed-function oxidase (MFO) system was investigated. Nine goats assigned to three groups were given a jugular infusion of [14C]3MI (0.02 to 0.03 g of 3MI/kg of body weight containing 0.5 muCi/kg of body weight) for 1.5 hours to induce acute pulmonary edema. Two groups of three goats each were treated with phenobarbital (PB) or piperonyl butoxide (BT) prior to 3MI infusion to induce or to inhibit the MFO system. Three goats were used as 3MI controls. During a 72-hour test period, blood was collected for determination of plasma 3MI concentration and radioactivity. Urine was collected and was fractionated by column chromatography. The severity of pulmonary lesions was evaluated by gross and microscopic examination. Pretreatment with BT prevented the onset of acute pulmonary edema. Goats pretreated with PB had more severe lung lesions than did 3MI controls. Plasma of goats pretreated with BT had a longer half-life (2.1 hours) of radioactivity, whereas plasma of goats pretreated with PB had a shorter half-life (1.0 hour) when compared with plasma of 3MI control goats (1.5 hours) given the same dosage of [14C]3MI (P less than 0.025). The plasma half-life of 3MI was longer (P less than 0.025) in BT-pretreated goats (0.45 hour) than that in PB-pretreated goats (0.26 hour). At 72 hours, 70% to 98% of the infused radioactivity had been excreted in the urine. The pattern of urinary metabolites of 3MI was altered in BT-pretreated goats compared with patterns in control and PB-pretreated goats. Results indicate that the MFO system is one of the pathways involved in the metabolism of 3MI and that pulmonary toxicosis results from metabolism of 3MI by this enzyme system.

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↗
PubMed1977

Ecdysis: neural orchestration of a complex behavioral performance.

Cricket ecdysis (molting) requires continuously changing output in hundreds of motoneurons over a period of several hours, and exhibits considerable plasticity. Despite this complexity, analysis of identified motor units reveals a highly organized three-layered infrastructure, and indicates that the "small system" paradigm currently applied to simple invertebrate motor programs can be extended to much more sophisticated behavioral performances.

Animals↗