[Copper, zinc and aluminum contamination of blood specimens used for determination of these metals]

Increasing interest and demand in determinations of copper, zinc and aluminium in clinical biochemistry, led us to pay particular attention to problems of blood collection. We tested several blood collecting tubes for contamination by these metals. Evacuated tubes must be avoided; polystyrene and polypropylene tubes are apparently the least polluting. However, strict rules cannot be made, and each biochemist should test the blood collecting devices he wants to use for trace elements analysis.

Evidence of enrichment in glycine receptors of crude synaptic membranes from rat spinal cord following Triton X-100 treatment

Treatment of synaptic membranes from rat brainstem and spinal cord with the nonionic detergent Triton X-100 at 1-10 microliters/mg protein caused a marked increase in glycine receptor (3H)strychnine binding expressed per mg of residual membrane protein. The effect was maximal (220 +/- 6% of control) at 5 microliters Triton/mg protein, while higher concentrations caused progressive loss of strychnine binding ability of membranes (27 +/- 6% at 25 microliters Triton/mg protein). The increase in strychnine binding caused by low Triton X-100 reflected an increase in membrane Bmax, the kD being unaffected by the treatment. The affinity of glycine analogues for receptor sites was not appreciably affected by the detergent either. The findings suggest an enrichment of the synaptic membrane preparation in glycine receptors, caused by the solubilization by Triton of membrane constituents not related to the receptor sites.

Genetic and biochemical studies on perchloroethylene 'in vitro' and 'in vivo'

Perchloroethylene (PCE) was tested in a diploid strain (D7) of the yeast Saccharomyces cerevisiae in suspension tests with and without a mammalian microsomal activation system (S9) and 'in vivo' by the intrasanguineous host-mediated assay. In addition, enzyme alteration studies were performed in mice non-pretreated or pretreated with phenobarbital + beta-naphthoflavone. PCE did not induce any genetic effect either 'in vitro' or 'in vivo'. In the suspension test, PCE was more toxic without metabolic activation and less toxic with mammalian microsomal activation. The enzymatic determinations showed an increase of the aminopyrine demethylase activity and of the level of cytochrome P-450.

Presence of functionally active beta-adrenoceptors in rat mast cells. Correlation between (--)[3H]-dihydroalprenolol binding and inhibition of histamine release

The correlation between the binding of a beta-adrenoceptor antagonist, (--)[3H]-dihydroalprenolol (DHAP), and the adrenergic inhibition of histamine release by acetylcholine and by compound 48/80 was studied with isolated purified rat mast cells and in rat mast cell crude membrane fractions. Acetylcholine-evoked histamine release was inhibited by catecholamines, in the order isoprenaline greater than adrenaline greater than noradrenaline. Pretreatment of cells with (--)alprenolol antagonized the inhibitory effect of isoprenaline on acetylcholine-induced histamine release. 40/80-evoked histamine release was blocked by isoprenaline at significantly higher concentrations than those required to inhibit cholinergic histamine release. The inhibitory effect of isoprenaline was equally antagonized by preincubating mast cells with (--)alprenolol. Specific binding sites for DHAP have been demonstrated in rat mast cell membranes. The specific binding of DHAP was inhibited by adrenoceptor agonists and antagonists according to the stereospecificity of these compounds. A close correlation between the binding-inhibitory potency of various adrenergic compounds and the data obtained in the pharmacological experiments was found, thus indicating the presence of beta-adrenoceptors in rat mast cells.

Direct evidence that eseroline possesses morphine-like effects

The opiate-like effects of eseroline, a physostigmine derivative, were studied in different tests. The antinociceptive effect of eseroline given s.c. and intracerebrally could be detected in the rat hot plate test and was reversed by naloxone. The apparent pA2 values of naloxone demonstrated with eseroline and morphine were found to be equal, suggesting an effect on similar receptors. Eseroline also had opiate agonist activity on the isolated longitudinal muscle strip of guinea pig ileum and isolated nictitating membrane of the cat: presynaptically, it inhibited the contractions evoked by stimulation and its effect was antagonized by naloxone. Eseroline reduced acetylcholine release from the myenteric plexus of the longitudinal muscle strip when the cholinesterases had been inhibited by physostigmine. In addition, it was also found that eseroline antagonized the inhibitory effect of normorphine in the longitudinal muscle strip and potentiated the effect of exogenous acetylcholine on smooth muscle, both effects being attributed to its anticholinesterase activity. The analgesic effect of eseroline was not related to its anticholinesterase activity.

[Genetic activity of 1,2-dichloroethylene. B). In vivo studies: effect on microsomal enzymes]

Mutagenicity study "in vivo" (Intravenous host mediated assay) confirms suspension test results with cis- and trans -1,2-dichloroethylene: no genetic effects could be detected. Single and repeated doses of trans-1,2-DCE induced liver aminopyrine demethylase and cytochrome P-450 whereas the cis- isomer decreased them. Similar results were obtained after induction with phenobarbital + beta-Naphthoflavone.

[Genetic activity of 1,2-dichloroethylene. A). In vitro studies]

1,2-dichloroethylene cis and trans were tested for their ability to induce point mutation, mitotic gene conversion and mitotic recombination in a diploid strain (D7) of the yeast Saccharomyces cerevisiae in a suspension test with and without a mammalian microsomal activation system. In this test 1,2-DCE cis and trans were toxic but not genetically active even with S9 activation.

Reversible inhibition of acetylcholinesterase by eseroline, an opioid agonist structurally related to physostigmine (eserine) and morphine

The action of eseroline--(3aS,8aR)-1,2,3,3a,8,8a-hexahydro-1,3a,8-trimethylpyrrolo[2,3-b]indo l-5-ol--salicylate was tested on preparations of ChE from different sources and on the longitudinal muscle of guinea-pig ileum. While eseroline is eseroline is extremely weak-acting on horse serum BuChE (Ki = 208 +/- 42 microM), it is a rather strong competitive inhibitor of AChE's, its Ki being 0.15 +/- 0.08 microM, 0.22 +/- 0.10 microM and 0.61 +/- 0.12 microM in electric eel, human RBC and rat brain, respectively. Eseroline inhibitory action in AChE in independent of the duration of pre-incubation and appears fully developed in less than 15 sec. This action is also rapidly reversible; after pre-incubation followed by dilution, maximum enzymic activity is regained within 15 sec. The electrically-evoked contractions of the longitudinal strip were inhibited by concentrations of eseroline in the range 0.2-15 microM, while they were increased by concentrations over 20 microM. In the same preparation, without electrical stimulation, but in the presence of naloxone, eseroline induced contractions at concentrations higher than 5 microM. This effect was antagonized by atropine. The inhibitory activity of eseroline parallels, as regards selectivity, potency and kinetics, that of the phenolic anticurare agent edrophonium, while it differs markedly from that of physostigmine.

Hypothermia induced in rabbits by intracerebroventricular taurine: specificity and relationships with central serotonin (5-HT) systems

The intracerebroventricular (i.c.v.) injection of taurine produced a fall in core temperature, the extent of which was dependent on the thermal gradient between the body and the environment. Concurrently, a sudden rise in ear skin temperature, which was maximal in the cold and negligible at 30 degrees C, was observed. The fever induced by i.v. injection of Escherichia coli endotoxin was antagonized by taurine. High temperatures produced by i.c.v. injection of prostaglandin E1 were also suppressed by taurine. Intracerebroventricular injections of bicuculline and strychnine, but not those of picrotoxin or pentylentetrazol, were able to reduce hypothermia induced by taurine. Intracerebroventricular injection of the taurine reuptake inhibitor guanidinoethyl sulfonate, on the contrary, did enhance the hypothermic response to taurine. Injection (i.c.v.) of serotonin (5-HT) elicited a fall in core temperature which was not accompanied by a rise in ear skin temperature, but was antagonized by the concurrent injection of the 5-HT antagonist methysergide. Pretreating animals with p-chlorophenyl-alanine caused a significant fall of brain 5-HT contents and a reduction of the hypothermic response to taurine. The latter effect was also observed when the animals were i.c.v. pretreated either the methysergide or with the 5-HT reuptake blockers chlorimipramine and Lilly 110140. These findings give support to the hypothesis that taurine-induced hypothermia in rabbits mediated by some taurine sensitive cells and, at least in part, by serotonergic synaptic mechanisms.

Eseroline: a new antinociceptive agent derived from physostigmine with opiate receptor agonist properties. Experimental in vivo and in vitro studies on cats and rodents

We report that eseroline, until now thought devoid of any biological action, is a potent antinociceptive agent. Its antinociceptive action is stronger than that of morphine in all tests studied and, though shorter lasting than that of the latter, has a latency of only a few minutes by subcutaneous route. Eseroline, like morphine and enkephalins, inhibits the electrically evoked twitches of the mouse vas deferens and of the guinea-pig ileum. Eseroline, moreover, releases 5-hydroxytryptamine from cat brain cortex in way similar to that of morphine and physostigmine.

Effects of morphine, physostigmine and raphe nuclei stimulation on 5-hydroxytryptamine release from the cerebral cortex of the cat

1. The release of 5-hydroxytryptamine (5-HT) from the cerebral cortex and caudate nucleus of brainstem-transected cats and from the cerebral cortex of rats anaesthetized with urethane was determined by radioenzymatic and biological assay. 2. The stimulation of nucleus linearis intermedius of raphe doubles the basal 5-HT release in the caudate nucleus and increases it 3 fold in the cerebral cortex. The effects of the electrical stimulation of the raphe are potentiated by chlorimipramine. 3. Brain 5-HT release is greatly increased by morphine hydrochloride (6 mg/kg i.v.) and by physostigmine (100 microgram/kg i.v.), but not by DL-DOPA (50 mg/kg i.v.). 4. It is suggested that the 5-HT releasing action of physostigmine can contribute to some of its pharmacological effects such as the analgesic effect so far attributed exclusively to its indirect cholinomimetic activity. 5. The 5-HT releasing action of physostigmine seems unrelated to its anticholinesterase activity.

Effectiveness of simplified dosage schedules on the management of ambulant epileptic patients

The effect of dosage schedules on plasma drug levels was evaluated in two groups of ambulant epileptic patients, whose treatment with diphenylhydantoin (DPH) or phenobarbital (PB) had been simplified by reducing the daily frequency of the dosage regimens. Although the patients received the same milligram per kilogram daily dosages of DPH or PB during the study, the mean plasma levels of the two drugs were significantly higher during the less-frequent dosage regimens. The results obtained suggest that twice-daily dosage schedules of DPH and once-daily dosage schedules of PB are advantageous over more complicated dosage schedules resulting in a higher compliance among ambulant epileptic patients.

[Effect on serum aluminium levels of continued ingestion of aluminium gels by patients with chronic renal insufficiency (author's transl)]

Atomic spectrometric absorption without flame allows reliable determination of serum aluminium levels (S.A.). Serum level in 59 normal subjects taking no aluminium gel (A.G.) is 24.3 +/- 8.4 microgram/l. Similar value were observed in 27 patients with renal insufficiency even severe who do not take A.G. Mild elevation of S.A. (40 +/- 12 microgram/l) was observed in 21 dialysed patients receiving no A.G. S.A. elevation is related to the aluminium content of dialysis fluid. A.G. intake in patients with renal insufficiency is followed by increase of S.A. The levels increase in relation with the daily dose of A.G. The highest values are observed among dialysed patients. In 41 dialysed cases A.S. values are between 70 and 600 microgram/l. In 17 patients dialysed for a mean period of 47 months mean serum A.S. is 165 +/- 40 microgram/l. The precise role of aluminium intoxication in the genesis of the dialysis encephalopathy syndrom remains controversial. From a clinical point of view aluminium intoxication should be looked for in any patient with encephalopathy who is taking aluminium gels and/or who is dialysed.

[Plasma levels of diphenylhydantoin (DPH) and phenobarbitone (PB) in epileptic patients resistant to drug treatment (author's transl)]

The Authors present and discuss the results obtained by assaying plasma DPH and PB in 123 patients chronically treated with antiepileptic drugs. The subjects examined were considered resistant to medical therapy and were all at their first laboratory control. The data obtained show: 1) the very poor correlation existing between the doses of drugs administered and their actual plasma levels; 2) the very high percentage of patients with DPH and PB plasma levels not in the therapeutic range of these drugs. The Authors discuss some of the most frequent errors in planning chronic therapy with DPH and barbiturates due to the lack of knowledge of drug blood levels.

[Neuropathologic and toxicologic study of 12 cases of bismuth encephalopathy]

Examination of twelve cases of bismuth encephalopathy showed a constantand marked elevation of the bismuth levels in autopsy cerebral tissue (ranging from 2-8 mg/kg to 25 mg/kg). These values were found to be much higher than the last-measured Bismuth venous blood values. In every case, periveinular lymphocytic infiltration and abundant intra-cytoplasmic lipofuscin were seen. The microanalysis with Castaing's electrode revealed the presence of focal areas of bismuth in the leptomeningeal spaces. The significance of the lesions is not fully established and it will undergo further investigations.

Is taurine-induced hypothermia in the rat mediated by 5-HT?

Intraventricular administration of taurine in the rat caused hypothermia, the extent of which was directly dependent upon the thermal gradient between the body and the environment. Pre-treatment of animals with p-chlorophenylalanine, which depleted most of the brain serotonin, strongly reduced the hypothermia induced by taurine. Pre-treatment with alpha-methyltyrosine induced hypothermia and sedation in animals. When this was followed by a taurine injection, they exhibited a decrease in body temperature which fitted the curve relating thermal gradients to hypothermic responses. It is suggested that taurine induced hypothermia in rat is mediated in part by central 5-HT systems.