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Biomedical subjects

E B Nelson

Publications and source records attributed to E B Nelson.

At least 55 records · Page 3Linked to original sources
PubMed1986

Paracetamol absorption from a feeding jejunostomy.

Disposition of paracetamol oral elixir was determined in two male patients after administration via feeding jejunostomy and compared with four male controls who received the same dose by mouth. Area under the plasma concentration-time curve, elimination half-life, and time to maximum concentration were similar in both groups after 650 mg paracetamol elixir. The absolute amounts and ratio of paracetamol glucuronide to sulphate, the major urinary metabolites after therapeutic paracetamol doses, were similar after jejunal administration as compared to oral administration. Paracetamol is absorbed and biotransformed in a similar manner after either jejunal or oral administration. Therefore, it may be administered effectively via jejunostomy tube in patients who require this route of administration.

Acetaminophen↗
PubMed1980

Effectiveness of methyrapone in the treatment of acetaminophen toxicity in mice.

Metyrapone tartrate, 400 mg/kg i.p. raised the LD50 for acetaminophen from 340 mg/kg i.p. to 540 mg/kg i.p. in fasting male Swiss white mice. The minimum protective dose of metyrapone was 200 mg/kg. Metyrapone was effective in preventing death when given up to 2 h after acetaminophen administration. The LD50 for metyrapone tartrate was 760 mg/kg i.p. Metyrapone decreased or prevented acetaminophen induced hepatic damage measured either by histology or plasma glutamate pyruvate transaminase activity. Metyrapone tartrate, 400 mg/kg i.p., inhibited the severe liver glutathione depletion seen with acetaminophen alone. It is proposed that metyrapone protects mice from acetaminophen induced liver toxicity and death by inhibiting the oxidation of acetaminophen to a toxic intermediate.

Acetaminophen↗
PubMed1980

Aspirin absorption from a feeding jejunostomy.

In a 67-year-old man who had a feeding jejunostomy because of dysphagia paralytica, the absorption of aspirin was measured in terms of serum salicylate concentration. A 975-mg dose of aspirin was given as a slurry in water directly into the feeding tube. Peak serum levels of salicylate were well correlated with those in previous studies of aspirin absorption by the oral route in a geriatric population. However, unexpectedly, the half-life of the drug in this patient was twice as long (7.5 hours) as that found in six previous studies (3.7 hours) of elderly patients given similar doses.

Aged↗
PubMed1980

The pharmacology and toxicology of meta-substituted acetanilide I: acute toxicity of 3-hydroxyacetanilide in mice.

Toxicity of meta or 3-hydroxyacetanilide was evaluated in mice. The LD50 was 1025 mg/kg when given intraperitoneally (i.p.). The drug in doses greater than 400 mg/kg i.p. caused significant sedation. 3-Hydroxyacetanilide, 900 mg/kg i.p., did not cause hepatic necrosis evaluated by either histology or changes in plasma glutamate pyruvate transaminase activity. Acetaminophen (4-hydroxyacetanilide, paracetamol) caused significant liver glutathione depletion two hours after dosing. In contrast, liver glutathione was only slightly decreased by 600 mg/kg i.p. of 3-hydroxyacetanilide at 2 or 4 hours after the dose. It is suggested that the meta-substituted acetanilide derivatives might be safer analgesics and antipyretics than acetaminophen.

Acetaminophen↗
PubMed1975

Steroid hydroxylations by human adrenal cortex microsomes 1, 2.

Microsomes were prepared from human adrenals obtained at the time of cadaveric renal transplantation. Microsomes were assayed for cytochrome P-450 concentrations (mean =0.63 nmol/mg protein) and NADPH-cytochrome c reductase activity (mean 65 nmol times min-1 times mg-1 protein). Rates of steroid hydroxylation were measured. In man, the rate of 21-hydroxylation of 17-hydroxyprogesterone was approximately three times the rate of 21-hydroxylation of progesterone. The rate of 17-hydroxylation of progesterone was approximately three times the rate of 21-hydroxylation of progesterone. Substrate binding to microsomes showed a type I spectrum with progesterone and 17-hydroxy-progesterone. Both substrates bound all spectrally identifiable sites. Antibody prepared against procine NADPH-cytochrome c reductase inhibited concomitantly human reductase, 21-hydroxylation of progesterone and 17-hydroxyprogesterone, and 17-hydroxylation of progesterone. These results were compared to previous studies with beef adrenal microsomes. No specific evidence was obtained to suggest multiple forms of 21-hydroxylase in human adrenal microsomes. It appears as though the human adrenal microsomal cytochrome P-450 electron transport chain is immunologically similar to those studied previously--beef adrenal, and rat and human liver.

Adrenal Cortex↗
PubMed1970

Glycolate pathway in green algae.

By three criteria, the glycolate pathway of metabolism is present in unicellular green algae. Exogenous glycolate-1-(14)C was assimilated and metabolized to glycine-1-(14)C and serine-1-(14)C. During photosynthetic (14)CO(2) fixation the distributions of (14)C in glycolate and glycine were similar enough to suggest a product-precursor relationship. Five enzymes associated with the glycolate pathway were present in algae grown on air. These were P-glycolate phosphatase, glycolate dehydrogenase (glycolate:dichloroindophenol oxidoreductase), l-glutamate:glyoxylate aminotransferase, serine hydroxymethylase, and glycerate dehydrogenase. Properties of glycerate dehydrogenase and the aminotransferase were similar to those from leaf peroxisomes. The specific activity of glycolate dehydrogenase and serine hydroxymethylase in algae was 1/5 to 1/10 that of the other enzymes, and both these enzymes appear ratelimiting for the glycolate pathway.Labeling patterns for products of the glycolate pathway during (14)CO(2) fixation are not the same as those obtained with higher plants. In higher plants glycolate, glycine, and serine are uniformly labeled at shortest time periods. In algae, serine was predominately carboxyl-labeled, similarly to 3-phosphoglycerate. This result, plus the lower specific activity of serine hydroxymethylase, indicates that the glycine-serine interconversin in algae is slower than in plants. Initially (2 to 4 seconds) glycolate and glycine were more C-2 labeled. They rapidly became uniformly labeled, with glycine becoming uniformly labeled first. In the presence of isonicotinylhydrazide, labeled glycolate and glycine accumulated, and only a trace of serine-(14)C was detected. Then glycolate and glycine were initially carboxyl-labeled, and glycolate became uniformly labeled almost immediately and before glycine. These results suggest rapid metabolism of glycolate and glycine, in addition to the glycolate pathway.

Journal Article↗
PubMed1969

Glycolate stimulation of oxygen evolution during photosynthesis.

Glycolate and glyoxylate stimulated 100% to 300% the rate of oxygen evolution by Scenedesmus in the light in the absence of added carbon dioxide. This stimulation occurred either aerobically or anaerobically, and was sensitive to CMU. Aerobic dark respiration was stimulated 25% to 100% by glycolate. This phenomenon was best demonstrated with synchronized Scenedesmus at the stage of cell division. For glycolate stimulation of oxygen evolution, a dark preincubation of 1 minute or less was necessary. In comparative test with other compounds of metabolism and photosynthesis, the stimulation of oxygen evolution was greatest by glycolate and glyoxylate. In a proposed scheme glyoxylate serves as a terminal hydrogen acceptor from NADPH produced by photosynthesis, and it thereby stimulates oxygen evolution when carbon dioxide is not available. Transformation of glycolate to glyoxylate in these cells would have to occur in the absence of oxygen.

Eukaryota↗