Volitional ethanol consumption affects overall serotonin metabolism in Syrian golden hamsters (Mesocricetus auratus).

Methods were established for the determination of serotonin (5-HT)(1) metabolites 5-hydroxyindole-3-acetic acid (5-HIAA) and 5-hydroxytryptophol (5-HTOL) in the urine of Syrian golden hamsters (Mesocricetus auratus) and used to study the effect of volitional ethanol consumption on overall 5-HT metabolism in this ethanol-preferring rodent. The basal levels of 5-HIAA and 5-HTOL in 24-h urine of ethanol-naive hamsters were 300 +/- 101 and 4.96 +/- 1. 06 nmol (n = 8), respectively. Given free choice between water and a 15% ethanol solution, these hamsters chose to consume increasing amounts of ethanol. The increase was accompanied by a concomitant decrease in urine 5-HIAA and increase in urine 5-HTOL, indicating that volitional ethanol intake diverted part of the 5-HT metabolic flux from an oxidative into a reductive pathway. In a separate experiment, the amounts of ethanol consumed by and blood ethanol concentrations attained in ethanol-drinking golden hamsters were determined at 5 different time intervals between 6 PM and 7 AM when most feeding activities occurred. Except in the first hour after lights were turned off, ethanol was consumed at a relatively even pace throughout the night (2-3 g/kg/3 h) and blood ethanol levels were maintained at the low mM range which rarely exceeded 2 mM. These results suggest that the biochemical pathway that catalyzes 5-HT metabolism is extremely sensitive to ethanol and can play an important role in mediating the reported clinically beneficial action of a low concentration of ethanol during alcohol detoxification.

Variations in response of four lines of ring-necked pheasants to infection with marble spleen disease virus.

This study evaluated the response and susceptibility of four lines of ring-necked pheasants to infection with marble spleen disease (MSD) virus. Fifteen birds of the following lines were used: the standard ring-necked gamebird, the highly inbred jumbo white, the Sichuan, and the first-generation cross of the Sichuan and the standard gamebird. Baseline immune responses were assessed at 6 weeks of age by lymphoblastogenesis assays. All birds were orally challenged at 7 weeks of age with cell -culture-propagated MSD virus. Eight birds of each group were necropsied at 6-7 days post-inoculation (PI), and gross splenic lesions were recorded. Appropriate tissue sections were collected, fixed in 10% buffered formalin, and routinely processed for microscopic evaluation. The remaining birds were bled weekly from week 2 through week 8 Pl. Serum was tested for antibodies to MSD virus using a commercial enzyme-linked immunosorbent assay kit. Results of the lymphoblastogenesis assays and the gross and microscopic lesion incidences indicated that variations did exist between several lines evaluated. The jumbo white pheasant had significantly higher lymphoblastogenesis stimulation index and was more resistant to developing gross and histologic lesions than was the standard ring-necked gamebird.

Potentiation of the bioavailability of daidzin by an extract of Radix puerariae.

The dose effect of pure daidzin on the suppression of ethanol intake in Syrian golden hamsters was compared with that of crude daidzin contained in a methanol extract of Radix puerariae (RP). EC50 values estimated from the graded dose-response curves for pure daidzin and RP extract daidzin are 23 and 2.3 mg per hamster per day, respectively. Apparently the antidipsotropic activity of the RP extract cannot be accounted for solely by its daidzin content (22 mg/g). In addition to daidzin, six other isoflavones were identified in the RP extract and quantified--namely, puerarin (160 mg per g of extract), genistin (3.7 mg/g), daidzein (2.6 mg/g), daidzein-4',7-diglucoside (1.2 mg/g), genistein (0.2 mg/g), and formononetin (0.16 mg/g). None of these, administered either alone or combined, contributes in any significant way to the antidipsotropic activity of the extract. Plasma daidzin concentration-time curves determined in hamsters administered various doses of pure daidzin or RP extract by i.p.injection indicate that the crude extract daidzin has approximately 10 times greater bioavailability than the pure compound. Reconstruction of the dose-response effects for pure and crude daidzin using bioavailable daidzin rather than administered dose gives a single curve. Synthetic daidzin added to the RP extract acquires the bioavailability of the endogenous daidzin that exists naturally in the extract. These results show that (i) daidzin is the major active principle in methanol extracts of RP, and (ii) additional constituents in the methanol extract of RP assist uptake of daidzin in golden hamsters.

Daidzin suppresses ethanol consumption by Syrian golden hamsters without blocking acetaldehyde metabolism.

Daidzin is a potent, selective, and reversible inhibitor of human mitochondrial aldehyde dehydrogenase (ALDH) that suppresses free-choice ethanol intake by Syrian golden hamsters. Other ALDH inhibitors, such as disulfiram (Antabuse) and calcium citrate carbimide (Temposil), have also been shown to suppress ethanol intake of laboratory animals and are thought to act by inhibiting the metabolism of acetaldehyde produced from ingested ethanol. To determine whether or not daidzin inhibits acetaldehyde metabolism in vivo, plasma acetaldehyde in daidzin-treated hamsters was measured after the administration of a test dose of ethanol. Daidzin treatment (150 mg/kg per day i.p. for 6 days) significantly suppresses (> 70%) hamster ethanol intake but does not affect overall acetaldehyde metabolism. In contrast, after administration of the same ethanol dose, plasma acetaldehyde concentration in disulfiram-treated hamsters reaches 0.9 mM, 70 times higher than that of the control. In vitro, daidzin suppresses hamster liver mitochondria-catalyzed acetaldehyde oxidation very potently with an IC50 value of 0.4 microM, which is substantially lower than the daidzin concentration (70 microM) found in the liver mitochondria of daidzin-treated hamsters. These results indicate that (i) the action of daidzin differs from that proposed for the classic, broad-acting ALDH inhibitors (e.g., disulfiram), and (ii) the daidzin-sensitive mitochondrial ALDH is not the one and only enzyme that is essential for acetaldehyde metabolism in golden hamsters.

Rabbit liver class III alcohol dehydrogenase: a cathodic isoform with formaldehyde dehydrogenase activity.

Electrophoresis of rabbit liver homogenate on starch gel followed by activity staining revealed multiple forms of alcohol dehydrogenase (ADH) which, based on their electrophoretic mobilities, had been tentatively labeled as class "I," class "II," and class "III" ADHs. The class II enzyme has now been purified to homogeneity by ion exchange and affinity chromatography and, except for an isoelectric point of 7.7, closely resembles human class III ADH. It is a homodimer of molecular weight near 80,000 with a similar amino acid composition and comparable kinetic parameters for the oxidation of primary alcohols. Like the rat, human, and Escherichia coli class III ADHs, the rabbit enzyme is a glutathione-dependent formaldehyde dehydrogenase, and catalyzes the oxidation of S-hydroxymethylglutathione and the hemithiolacetal of 8-thiooctanoic acid. Ethanol up to 3 M does not saturate the enzyme, whereas longer chain primary alcohols exhibit Michaelis-Menten kinetics.

Elicited imitation: its effectiveness for speech and language screening.

The authors explored the clinical usefulness of a brief sentence-repetition screening task (SRST), by screening 382 kindergarten children and performing follow-up tests on a stratified sample of 78. Results indicate that an elicited-imitation task can predict the combined outcome of receptive and expressive language problems, as well as articulation problems. Replication, cross-validation and assessment of children with selective receptive impairments are recommended. Nevertheless, the present study demonstrates that the use of sentence-repetition screening tasks could be a very efficient strategy for screening for both language and articulation problems in kindergarten children.

An ion-selective microelectrode for bile salts.

The development of a prototype ion-selective microelectrode for bile salts is described. The microelectrodes demonstrated Nernstian response (59 +/- 10 mV dec-1) with sodium deoxycholate in Tris (0.2 M, pH 9.0, 15-30 degrees C), HEPES (0.13 M, pH 7.5), and bicarbonate buffers (0.1 M, pH 7.5) (25 +/- 0.1 degrees C) were stable for several days, and the responses were highly reproducible. The microelectrodes were selective for bile salts over the physiologically important inorganic anions, bicarbonate and chloride. The response to sodium cholate (42 mV dec-1) was consistently lower than the ideal response (59 mV dec-1). This ion-selective microelectrode may show promise as a useful tool for the determination of intracellular bile salt activity.