Ethanol interaction with propoxyphene and norpropoxyphene metabolism in isolated rat hepatocytes

Suspensions of isolated rat hepatocytes (approximately 7.5 X 10(5) cells/ml) metabolized added propoxyphene and norpropoxyphene rapidly. At 2 microM, the metabolism of both drugs obeyed first-order elimination kinetics. Increasing propoxyphene concentrations (1, 2, 4 and 8 microM) gradually increased the medium concentrations of norpropoxyphene. The total propoxyphene metabolism was the same at 4 and 8 microM. The effect of ethanol (10 and 60 mM) on propoxyphene (2 microM) and norpropoxyphene (2 microM) metabolism in suspensions of isolated rat hepatocytes was studied. The half-lives of propoxyphene were 7.1 +/- 5.5 min in absence and 6.7 +/- 2.8 min in presence of 10 mM ethanol, but increased to 10.7 +/- 5.8 min in presence of 60 mM ethanol (p less than 0.05). The half-lives of added norpropoxyphene increased from 17.9 +/- 4.1 min to 26.0 +/- 7.3 min at 10 mM ethanol (p less than 0.05) and 29.3 +/- 5.9 min at 60 mM ethanol (p less than 0.05). Ethanol (60 mM) reduced the elimination rate constant of propoxyphene and norpropoxyphene by 31 +/- 25% and 38 +/- 15%, respectively.

[Prognostic significance of ventricular echo beats induced during programmed ventricular stimulation (author's transl)]

To determine the incidence and prognostic significance of the repetitive ventricular response, the present retrospective study was done in 123 patients (75 male, 48 female, mean age +/- S.D. 49 +/- 14 years) with a variety of cardiac rhythm disorders. Programmed right ventricular stimulation was done at a basic pacing rate of 120 b.p.m. using one (S2) and two (S2,S3) premature stimuli. The data were analysed as to the presence ro absence of a repetitive ventricular response and the outcome of the patients ((1) sudden death less than or equal to 1 h or documented ventricular fibrilllation without myocardial infaction without myocardial infarction; (2) survivors or patients dying from non-cardiac or non-suddenly). A repetitive ventricular response was observed in 45/123 patients (36.6%) after one and in 51/120 patients (42.5%) after two premature stimuli. It occurred in 9/9 patients with ventricular fibrilation and in 20/23 patients (87%) with ventricular tachycardia. Mean follow-up period was 84 +/- 37.1 weeks (+/- S.D.). Five patients were lost to follow-up. 17/123 patients were classified as sudden death patients, the remaining patients were regarded as surviving (or dying non-suddenly). After one premature stimulus, a repetitive ventricular response was observed in 34.9% of survivors and in 47.1% of non-survivors (n.s.). After two premature stimuli, the incidence of a repetitive ventricular response increased from 36.8% in survivors to 70.6% in non-survivors (p less than 0.005). 12/106 of patients (11.3%) surviving and 10/17 patients (58.8%) non-surviving had more than three ventricular echo beats (p less than 0.005). All patients non-surviving who demonstrated a repetitive ventricular response has intraventricular reentry. Depending on the regidity of the criteria used (i.e. number of echo beats), the sensitivity of the test ranged between 47 to 88%, whereas the specificity ranged between 44 to 94%. The number of false-positives was high (43 to 80%); however, the number of false-negatives was low (4 to 8%). Concluding, this retrospective study has shown a correlation between sudden death and the incidence and number of repetitive ventricular response (depending on the number of premature stimuli) and the type of reentrant beats (bundle branch reentry or intraventricular reentry).

Treatment of dopamine-dependent shock with triiodothyronine

At the present time dopamine is the most frequently used treatment in patients with septic shock. The effects of dopamine are mediated by alpha-, beta- and dopaminergic receptors. It has been suggested that these receptors are controlled by triiodothyronine (T3). In acute septic shock circulating T3-concentrations are decreased. We have, therefore, treated in a preliminary study 11 such patients with T2-replacement by continuous infusion of T3 (100-200 micrograms/24h). Dopamine dependence was terminated. In all patients there was an increase of arterial blood pressure (BP) within 24 hrs (systolic BP rose by 34 +/- 4.2 mmHg, diastolic BP by 14.0 +/- 8.2 mmHg, resulting in an increase of the mean BP by 25 +/- 6.1 (SEM mmHg). The pulse rate was not influenced suggesting an effect on minute volume. A hypothesis is offered which explains the T3-effects as a result of its decarboxylation to a dopaminergic iodothyronine which is disturbed during the "low T3-syndrome".

[Treatment of dopamine-dependent shock with triiodothyronine: prelimary results (author's transl)]

Triiodothyronine (T3) was administered to 11 patients in septic shock. In all there occurred an increase in arterial blood pressure within 24 hours, the rise in systolic pressure being 34 +/- 4.2 mm Hg, of diastolic 14 +/- 8.2 mm Hg, corresponding to a rise in mean arterial pressure of 25 +/- 6.1 mm Hg. Haemodynamic studies in four patients suggest that the action of T3 is mediated via beta-sympathomimetic channels.

Storage of blood samples containing alcohol

The storage of blood alcohol samples was studied. The samples were analysed and then frozen and kept at -20 degrees for 6 months before reanalysis. The results from this reanalysis did not deviate to any significant extent from those originally obtained. The process of freezing and thawing the same samples before analysis was repeated three times without any significant difference from the results with the fresh blood samples.

Choline acetyltransferase induction in cultured neurons: dissociated spinal cord cells are dependent on muscle cells, organotypic explants are not

The dependence of the induction of choline acetyltransferase (CAT) on the type of tissue culture, monolayer or piece explants, of spinal cord (SC) and muscle (M) was studied. CAT activities of dissociated SC cells were low but were increased by M monolayers. In piece explants of SC, high CAT activities were achieved independently of muscle cells (chick, mouse). It is therefore likely that in tntact SC tissue factors other than the trophic influence of muscle are able to induce cholinergic maturation. M piece explants on SC monolayers did not induce CAT in, and their outgrowth was inhibited by, SC monolayers.

The metabolism of biphenyl. V. Phenolic metabolites in some marine organisms

The phenolic metabolites of biphenyl in the crustacean Cirolana borealis LILJEBORG (ISOPODA), the gastropod Buccinum undatum L and the ophiuroid Ophiocomina nigra ABILDGAARD have been analysed qualitatively and semi-quantitatively as trimethylsilyl (TMS) ethers by combined gas chromatography/mass spectrometry and gas chromatography, respectively. The findings demonstrate the in vivo metabolic capacity of these organisms to convert biphenyl into its hydroxylated derivatives. Thus, 2-hydroxybiphenyl is the most prominent metabolite detected in all these experiments, which also showed that minor amounts of the 4-hydroxy and 4,4'-dihydroxy metabolites are formed. Metabolites of biphenyl origin are found both in the sea water from the aquaria and in the tissue of the respective marine organisms. The experiments, moreover, indicate a slow metabolism of biphenyl in C. borealis, B. undatum and O. nigra, between which no qualitative metabolic differences are found.

The metabolism of biphenyl. IV. Phenolic metabolites in the guinea pig and the rabbit

The phenolic metabolites of biphenyl in guinea pigs and rabbits were qualitatively and quantitatively analysed as trimethylsilyl (TMS) ethers by combined gas chromatography/mass spectrometry and gas chromatography, respectively. The parent compound was hydroxylated to monohydroxylated biphenyls and minor amounts of dihydroxylated derivatives, and the main route of body clearance appeared to be by the urine in both species. Thus, in the urine of guinea pigs 32.9% of the dose was detected 96 hrs after dosing, while the major part (29.5%) was eliminated during the first day as conjugates. The main metabolite was 4-hydroxybiphenyl (25.5%). During the first 24 hrs faecal recovery was 20.3% of the dose, and most of this (14.3%) consisted of biphenyl itself. Biliary excretion of the metabolites of biphenyl origin amounted to 3.3% of the dose during the first day, and 4-hydroxybiphenyl was the major metabolite. In the urine of rabbits 49.1% of the dose was recovered 96 hrs after dosing, and most of this (25.4 and 15.9%, respectively) was eliminated during the first two days as conjugates. The major metabolite was 4-hydroxybiphenyl (35.3%). On the first day faecal recovery was 1.6%, of which 1.4% was detected as biphenyl itself. Less than 1% of the dose was found in the 7 hrs rabbit bile, and exclusively as 4-hydroxybiphenyl. The experiments thus show that both qualitative and quantitative differences in the metabolism of biphenyl exist between the guinea pig and the rabbit even though 4-hydroxybiphenyl was the most prominent metabolite of biphenyl in both species.

The question of histidine content in c-type cytochromes

Reports that histidine may not occur in heme peptides derived from c-type cytochromes isolated from chloroplasts of Euglena gracilis and Porphyra sp. have not been substantiated in the present investigation, in which the amino acid composition and a partial sequence were determined for a heme peptide derived from the c-type cytochromes of a strain of Euglena closely related to that used in the previous studies. It is concluded that no evidence exists to challenge the generalization that histidine is always present vicinal to the hemebinding site in c-type cytochromes.