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PubMed1986

Familial dysalbuminaemic hyperthyroxinaemia: studies of albumin binding and implications for hormone action.

The abnormal intermediate-affinity T4 binding to albumin which is characteristic of familial dysalbuminaemic hyperthyroxinaemia (FDH) is dependent on buffer, temperature, and ionic composition. Scatchard analysis of T4-binding to isolated albumin preparations from FDH subjects showed that half the circulating albumin showed the higher-affinity T4 binding site, assuming one site per molecule. Using dextran-charcoal separation at 4 degrees C the T4 affinity (Kd) of purified albumin from FDH subjects was 7.5 nmol/l in phosphate and 17 nmol/l in Tris-Cl- buffer. T4 binding to FDH albumin was inhibited by a range of substances in the order: 8-anilino-1-naphthalene sulphonic acid greater than merthiolate greater than propylthiouracil greater than methyl-thiouracil greater than carbimazole greater than salicylate greater than barbitone. Binding of T4 was competitively inhibited by low concentrations of dithiothreitol (DTT). The effect of DTT 0.1-0.5 nmol/l was reversed by removal of DTT by dialysis. Competition with a range of iodothyronines indicated that the 3', 5'-iodine atoms are most important for binding to this site. Serum binding of salicylate, frusemide, fenclofenac and barbituric acid, and a range of steroid hormones was similar in FDH and normal sera. Serum levels of sex hormone binding globulin (SHBG), were not significantly different from sex-matched controls. Nuclear [125I]-T3 binding sites in circulating lymphocytes from two FDH subjects showed affinities (Kd) of 59 and 79 pmol/l (normal 67 +/- 7 pmol/l, n = 6). These findings suggest that the highly specific binding anomaly of FDH is due to a disulphide-dependent structural change in albumin.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Protein Disorders↗

PubMed1989

[Induction of lipid peroxidation and change of fatty acid composition in rats fed methylmercury].

Four groups of rats, with 5 animals in each, were fed a diet to which 1, 2, 4 or 8 ppm of methylmercury (MeHg) were added while another group of 5 rats was fed a diet containing no MeHg as a control. Moreover, each rat was daily supplied the same volume of these diets. During the experimental period of 40 days, body weights of the rats were daily checked individually. On day 40, expired air of the rats was collected to analyse for ethane and pentane production, and then the rats were sacrificed to obtain the liver, kidneys, brain and plasma. Thio-barbituric acid (TBA)-reactants in the selective organs and plasma were measured to investigate the effects of MeHg on lipid peroxidation. Further, gas-chromatographic analyses of fatty acids were carried out on the samples of the selective organs and plasma to examine the effects of MeHg on lipid metabolism. Results obtained were as follows: 1. The fifth day after the experiment started, the growth rates of the groups fed a diet containing MeHg (the MeHg groups) were higher than those of the control group. Moreover, the growth rates tended to increase with increases of MeHg concentrations in food from days 25 to 32 of the experimental period. Furthermore, the weights of the kidneys increased with increases in MeHg concentrations in food. 2. The amounts of expired ethane and pentane did not increase proportionally with increases in MeHg concentrations in food but those of expired ethane and pentane were higher in the MeHg groups than in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

gamma-Aminobutyric acid antagonism produced by an organophosphate-containing combustion product.

Results from [35S]t-butylbicyclophosphorothionate (TBPS) binding and gamma-aminobutyric acid (GABA)-dependent 36Cl- uptake indicated that the pyrolysis product of liquid trimethylol propane (TMP) containing organic phosphates interacts with the GABA/benzodiazepine receptor chloride ionophore complex (GBRC) producing a receptor-mediated reduction in 36Cl- flux. The pyrolysate-ligand interaction was competitive and directly proportional to the trimethylol propane phosphate (TMPP) content of the combustion product. TBPS displacement demonstrated that TMPP had less affinity than did TBPS and picrotoxin, but greater affinity than GABA, racemic dimethylbutyl barbituric acid (DMBB), clonazepam, and phenobarbital for their respective recognition sites. Addition of exogenous GABA was a necessary condition for demonstrating clonazepam-induced ligand displacement, thus being indicative of an allosteric interaction. The same rank order held for altering GABA-dependent 36Cl- uptake with the caveat of inhibitors vs enhancers, and noting that pentobarbital was less potent than DMBB. Concentration-dependent ligand displacement by GBRC agonists and antagonists quantitatively correlated with alterations in GABA-dependent 36Cl- uptake. The median convulsant dose (CD50) of pyrolysate TMPP was higher than that of synthetic TMPP. The presence of combustion by-products altering the dispositional kinetics of the former is felt to be the reason for this difference. Under our experimental conditions, phenobarbital was the most effective antidote for pyrolysate (TMPP) toxicity. The inhalant convulsant, flurothyl, was found not to displace [35S]TBPS binding, not to affect GABA-dependent 36Cl- uptake, and not to respond to the anticonvulsants in a manner consistent with a strict GABAA receptor phenomenon.

Animals↗

PubMed1966

Production and stabilization of cells of Bacillus popilliae and Bacillus lentimorbus.

Bacillus popilliae and B. lentimorbus grew most rapidly and to the greatest extent in aerated cultures at 30 to 32 C with oxygen absorption rates of 1 mmole of O(2) per min per liter, or above. The control of pH also increased the maximal populations attained. Media were developed which consistently produced cell populations of about 10(9) within 24 to 48 hr in aerated cultures of these two species. The acetic acid produced in highly aerated cultures was shown not to be responsible for the rapid loss of cell viability in stationary phase cultures. However, H(2)O(2) was very lethal to cells of B. popilliae, and this species is known to have the capacity to produce it. Stationary-phase cells were partially stabilized by reducing the availability of oxygen after 24 hr of incubation on a shaker, and the addition of low levels of glucose further stabilized the cells. The most stable cells were those produced in a medium in which 4% Trypticase (BBL) and 0.1% barbituric acid were incorporated. A high percentage of these cells contained refractile bodies visible under a phase microscope. Although these bodies were not heat-resistant and lacked other characteristics of endospores, cells in cultures containing them had reasonably high viability for extended periods, as compared with those in control cultures.

Acetates↗

PubMed1991

Barbiturates in severe head injuries?

Possible mechanisms for the therapeutic effects of barbituric acid derivatives in severe head injuries have been discussed for half a century. In the following, a survey of the literature, and a discussion of three controlled clinical studies available until now is presented. A proven effect in terms of a beneficial long-term outcome for all injured patients has not been established. On the other hand there might be a subgroup of patients with an intact CO2 reactivity of the brain vessels who may profit from barbiturates administered after head trauma.

Barbiturates↗

PubMed1994

Deaths among drug addicts in Denmark in 1987-1991.

In the period 1987-1991 a total of 739 fatalities among drug addicts was investigated at the three University Institutes of Forensic Medicine in Denmark. The annual number rose from 130-140 in the first 4 years to 192 in 1991, and 80% were males. The mean and median age for both males and females increased by 1 year in the period. The main drug of abuse was heroin, in most cases supplemented by various other drugs, and in almost all cases taken intravenously. In about one-third of the cases each year there was information of abuse of alcohol in addition. In the poisoning cases, the main drug of poisoning was morphine/heroin, constituting 35-55% of the cases each year. As regards methadone-poisoning cases, the number increased significantly in 1991 compared to the first 4 years. Furthermore, the number and proportion of addicts dying while in methadone treatment increased during the 5-year period. In about half of the methadone poisoning cases, there was information of methadone treatment at the time of death. The other half obviously obtained the methadone completely illegally. Ketobemidone was the third most frequent drug of poisoning, while propoxyphene and barbituric acid only were found in a very few cases each. The results are compared to those from an earlier investigation concerning drug deaths in Denmark in 1968-1986. The importance of registering drug deaths is emphasized.

Adolescent↗

PubMed1976

Life-span investigations for carcinogenicity of some immune-stimulating, immunodepressive and neurotropic substances in Sprague-Dawley-rats.

In a long-term trial in a total of 858 Sprague-Dawley-rats of both sexes the possible carcinogenicity of 12 substances was investigated. Complete Freunds' adjuvant which is among the immune-stimulating substances was found to decrease significantly the lifetime of the animals; whereas an increase in tumor incidences was not observed. Bacille Calmette-Guérin (BCG), human albumin, and vitamin-A-acid were neither carcinogenic, nor had they an influence on the survival times. Rabbit-antirat lymphocytic serum which is a well-known immunodepressive agent caused a significant decrease in survival times, it was not found to be carcinogenic. The known carcinogenic properties of cyclophosphamide were verified. The applied dose of this compound significantly reduced the mean survival times of the animals. Hydrocortisone and amethopterin were found to have no carcinogenic effects. Atropine, pilocarpine, nicotine, and phenyl-ethyl-barbituric acid (phenobarbital) which are known to have neurotropic effects were tested. Nicotine and phenobarbital were found to diminish the mean survival times. None of these neurotropic substances was found to be carcinogenic.

Animals↗

PubMed1975

The metabolism of pyrimidines by proteolytic clostridia.

Uracil was used by growing cultures of Clostridium sporogenes, and by proteolytic strains of C. botulinum types A and B. Uracil was not used by C. bifermentans; C. botulinum, type B (non-proteolytic); C. botulinum, type F (non-proteolytic); C. botulinum, type E; C. butyricum; C. cochlearium; C. difficile; C. histolyticum; C. oedematiens, type A; C. paraputrificum; C. scatologenes; C. specticum; C. sordellii; C. sticklandii; C. tertium; C. tetani; C. tetanomorphum; C. welchii, types A, B, C, E and 4 untyped strains. The growth of C. sporogenes was not increased by uracil; it was reduced to dihydrouracil. Experiments with washed cells of C. sporogenes showed that the uracil-reducing system was inducible. Washed cell suspensions incubated under hydrogen with uracil, thymine, iso-barbituric acid, 5-amino uracil and cytosine consumed 1 mole H2/mole pyrimidine. The reduction product of cytosine was dihydrouracil indicating that it was deaminated before reduction. The reduction products of the remaining pyrimidines were the corresponding dihydro derivatives. Extracts of C. sporogenes reduced uracil in the presence of NADPH2 but not NADH2.

Barbiturates↗

PubMed1983

Diazepam, pentobarbital and D-etomidate produced increases in bicuculline seizure threshold; selective antagonism by RO15-1788, picrotoxin and (+/-)-DMBB.

The seizure threshold for different seizure components was measured after slow intravenous infusion of bicuculline in the rat. Clear differences were seen in the seizure threshold for tremor (TRE) and clonic-forepaw (CLOF) as compared to clonic-hindpaw (CLOH) and tonic-forepaw (TONF). Seizure threshold was measured after treatment with different doses of diazepam, pentobarbital, D-etomidate, picrotoxin, RO15-1788 and (+/-)-5-(1,3,-dimethylbutyl)-5-barbituric acid (DMBB). Direct and indirect antagonism between the agonists and antagonists was examined. The interactions between the drugs for TRE and CLOF resemble those described in in vitro receptor-binding assays using the GABA-benzodiazepine-chloride ionophore complex (GBCI). The interactions for CLOH and TONF do not show this resemblance, suggesting less involvement of GABA in these phenomena. Diazepam was selectively antagonized by RO15-1788. D-Etomidate and pentobarbital were directly antagonized by DMBB, suggesting shared activity at the barbiturate site. No evidence was found for an interaction between compounds acting at different sites within the GBCI.

Animals↗

PubMed1978

Effects of natural pyrimidines and of certain related compounds on the spontaneous activity of the mouse.

Uracil and perhaps other natural pyrimidines may effect the level of arousal of the mammalian brain since: 1) heterocyclic 6-membered rings, which resemble uracil, form part of the structure of many hypnotics; and 2) 6-azauracil (and its riboside) have shown to be hypnotic for several mammalian species, including man. The parenteral administration of uridine, 6-azauridine, cytidine or thymidine depressed the spontaneous activity of adult male C-57 mice. 6-Azauridine was much less potent than the other ribosides tested. Cytosine, barbituric acid, 2-thiobarbituric acid, 2,4-dihydroxypyridine and a variety of pyrimidine catabolites had no effect on activity. Thymine, uracil, 6-azauracil, barbital and phenobarbital increased activity at lower doses and decreased activity at higher ones. 6-Azauracil and uracil were about equally potent as stimulants of activity, but 6-azauracil had about twice the potency of uracil as a depressant of activity. Thymine, which was more active than uracil, had about 10% the potency of barbital, both as a stimulant and as a depressant of activity. For thymine and the two barbiturates the ED50 (for depression of activity) was of the same magnitude as the LD50, while the dose which caused 50% stimulation of activity was about an order of magnitude less than the LD50. These results suggest that the barbiturates might affect arousal by simulating the structure of thymine or uracil at some receptor.

Animals↗

PubMed1992

Disposition of heptabarbitone in the rat: identification of a new metabolite by tandem mass spectrometry.

The purpose of this study was to elucidate the structure of a metabolite of heptabarbitone, the occurrence of which was reported previously in a number of pharmacokinetic and pharmacodynamic modelling studies. By application of thermospray liquid chromatography (tandem) mass spectrometry, the identity of the metabolite was proposed to be 5-ethyl-5-(1',[3' or 6']-cycloheptadienyl)-barbituric acid. By measuring the ratios between the areas under the concentration time curves of the metabolite and heptabarbitone after administration of three different intravenous dosages of heptabarbitone, it was shown that the exposure to the metabolite is directly correlated with the exposure of heptabarbitone.

Animals↗

PubMed1982

A comparative study of the efficacy of four barbiturates as promoters of the development of gamma-glutamyltranspeptidase-positive foci in the liver of carcinogen treated rats.

The promoting action of four barbiturates, and their modulation of the promoting action of a choline-devoid (CD) diet was investigated by quantitating the gamma-glutamyltranspeptidase (GGT)-positive foci which developed in the liver of rats exposed to a single injection of diethylnitrosamine. Phenobarbital (PHB), pentobarbital (PTB) and amobarbital (AMB), exerted a promoting action, while barbituric acid (BA) had no effect. Addition of PHB or PTB to a CD diet resulted in a synergistic promoting action, but AMB had only an additive effect. Feeding a CD diet to rats caused a stimulation of liver DNA synthesis and of cell proliferation. These effects of the diet were markedly inhibited by addition of PHB or PTB, while addition of AMB resulted only in an inhibition of the enhanced proliferation of hepatocytes. No inhibitory effect was exerted by BA. The results indicate that the liver tumor promoting action of PHB and of barbiturates is dependent upon biological effects related to the presence of an alkyl group in their side chain. It is hypothesized that the promoting action of the agents herein studied may involve two components, a stimulation of the proliferation of initiated liver cells, and a suppression of the proliferation of non-initiated cells.

Animals↗

PubMed2002

Changes in circulatory antioxidant status in horses during prolonged exercise.

Prolonged low-medium intensity exercise is associated with increased oxidative stress in humans. We hypothesized that competitive equine endurance racing would induce changes in circulatory antioxidants and produce systemic oxidative stress. Forty horses competing in a 140-km endurance race in warm conditions [shade temperature 15-19 degrees C; 62-88% relative humidity (%RH)] were sampled before (Pre), immediately after exercise (End) and at approximately 16 h into recovery (+16 h). Plasma ascorbic acid concentration was not different between Pre [11.1 (median); 4.6-20.3 micromol/L (range)] and End [9.7; 3.0-38.9 (range) micromol/L] but was significantly decreased at +16 h (5.5; 2.8-15.5 micromol/L; P < 0.05). Total red cell hemolysate glutathione (TGSH) concentration was significantly reduced by exercise (Pre 1261; 883-1532 micromol/L; End 1065; 757-1334 micromol/L; P < 0.05) and at +16 h recovery (1032; 752-1362 micromol/L; P < 0.05). Glutathione redox ratio was unchanged by exercise but was significantly decreased at +16 h compared with that at both Pre and End (P < 0.05). The concentration of total barbituric acid reactive substances (TBARS) in plasma was increased compared with that at Pre (309; 66-1048 nmol/L), both at End (408; 170-1196 nmol/L; P < 0.05) and +16 h (380; 99-1161 nmol/L; P < 0.05). alpha-Tocopherol was unchanged by exercise or recovery. Mean race speed was 16.5 +/- 1.6 km/h and ranged from 13.9 to 19.7 km/h. Mean speed during competition in horses that completed the full 140 km (n = 28) was significantly correlated with end of exercise ascorbic acid (r = 0.622; P = 0.0004). Although there were increases in creatine phosphokinase (CK), aspartate aminotransferase (AST) and TBARS and a loss of TGSH, this study failed to demonstrate evidence of classical oxidative stress.

Animals↗

PubMed1983

A new, less toxic polymerization system for the embedding of soft tissues in glycol methacrylate and subsequent preparing of serial sections.

The paper describes a new polymerization system for embedding soft tissues in glycol methacrylate (GMA). The polymerization of GMA is initiated by means of a barbituric acid derivative in combination with chloride ions and dibenzoyl peroxide. The catalyst system contains no aromatic amines which constitutes a toxicological advantage over the commonly employed system of peroxide/aromatic amine. Clear blocks are obtained from which 1-2 micrometers sections are easy to cut. In combination with an appropriate softener, polyethylene glycol 400, serial sectioning may be practiced.

Acrylates↗

PubMed1976

Synthesis of some quinazolone derivatives structurally related to certain sedatives and hypnotics.

The preparation of certain 3-substituted derivatives of 3.4-dihydro-2-methyl-4-oxoquinazoline is described. The synthesis fo a quinazolone-barbituric acid derivative, in which the two constituting moieties are separated by methylene groups, was achieved by reacting 3-[B-haloethyl]-3.4-dihydro-2-methyl-4-oxoquinazoline with sodio malonic ester and subsequent cyclization of the ester so formed with urea. Attempts to introduce the alpha-glutaryl group at the position 3 of the quinazolone ring system via different routes were unsuccessful.

Barbiturates↗

PubMed1984

Liquid chromatographic determination of lipophilicity with application to a homologous series of barbiturates.

A graphical method for determining the lipophilicity of the members of a homologous series of barbituric acids, from a consideration of their reverse-phase HPLC retention data, is described. The HPLC parameter used as the index of lipophilicity, RQ, is shown not only to form excellent correlations with the more commonly employed indices of lipophilicity, Rm and log P, but also to have a predictive capability for those log P values that had not previously been determined experimentally.

Barbiturates↗

PubMed1996

Inhibition of gap junctional intercellular communication by barbiturates in long-term primary cultured rat hepatocytes is correlated with liver tumour promoting activity.

Rodent liver tumor formation can be promoted by certain barbiturates and this may involve their ability to inhibit hepatocyte gap junctional intercellular communication (GJIC). In order to address the mechanisms and specificity of action of barbiturates on hepatocyte gap junctions, we have compared the effects of liver tumor-promoting barbiturates (phenobarbital, sodium barbital and amobarbital: PB, SB and AB, respectively) and a non-liver tumor-promoting barbiturate (barbituric acid: BA) on primary cultured rat hepatocyte GJIC and connexin32 (Cx32) expression after short (1-24 h) and long (2-14 days) treatment. GJIC was evaluated by fluorescent dye microinjection (dye-coupling); Cx32 expression was monitored by Northern blot, Western blot and immunohistochemistry. Both parameters were maintained at high levels over 14 days by coculture of the cells with WB-F344 rat liver epithelial cells in the presence of dexamethasone. Treatment with PB (2 mM) for 1 h sharply reduced dye-coupling from approximately 90-30%, but the cells fully recovered by 24 h. No inhibition was seen with the other barbiturates over this 1-day treatment period. Longer treatments (2-14 days) with the promoters PB, SB and AB, however, gradually reduced hepatocyte dye-coupling to approximately 30-50%. The non-promoter, BA, did not affect hepatocyte GJIC. These decreases in hepatocyte dye-coupling occurred without changes in Cx32 or gap junction expression. Dye-coupling of WB-F344 cells and expression of their predominant gap junction protein, connexin43 (Cx43), were also not affected. Thus, the inhibition of GJIC was specific to liver tumor promoting barbiturates in hepatocytes, was time-dependent and was not due to altered Cx32 expression.

Animals↗

PubMed1994

Rapid estimation of bacterial antibiotic susceptibility with flow cytometry.

Bacterial antibiotic susceptibility was rapidly estimated for Escherichia coli and Staphylococcus spp. by flow cytometry. This was achieved by measuring the uptake of a negatively charged membrane potential sensitive dye bis-(1,3-dibutyl-barbituric acid) trimethine oxonol and observing changes in low-angle light scatter (excitation light scattered by up to 15 degrees). Estimations of ampicillin, gentamicin and ciprofloxacin susceptibilities were possible within 2-5 h from a plate culture, depending on the species and antibiotic used. This includes the time necessary to establish steady-state growth in liquid culture.

Anti-Bacterial Agents↗