Prospect for a 60 GHz multicharged ECR ion source.

The conceptual design of a fourth generation hybrid electron cyclotron resonance (ECR) ion source operated at 60 GHz is proposed. The axial magnetic mirror is generated with a set of three Nb3Sn coils, while the hexapole is made with room temperature (RT) copper coils. The motivations for such a hybrid development are to study further the ECR plasma physics and the intense multicharged ion beams' production and transport at a time when a superconducting (SC) hexapole appears unrealistic at 60 GHz. The RT hexapole coil designed is an evolution of the polyhelix technology developed at the French High Magnetic Field Facility. The axial magnetic field is generated by means of 3 Nb3Sn SC coils operated with a maximum current density of 350 A/mm2 and a maximum coil load line factor of 81%. The ECR plasma chamber resulting from the design features an inner radius of 94 mm and a length of 500 mm. The radial magnetic intensity is 4.1 T at the wall. Characteristic axial mirror peaks are 8 and 4.5 T, with 1.45 T minimum in between.

Chromosomes 4 and 13 in beta-carboline-induced seizures in mice: benzodiazepine binding.

Methyl beta-carboline-3-carboxylate (beta-CCM) is a ligand for the benzodiazepine (BZD) binding site of the GABA-A receptors with convulsive properties. We provided evidence for the involvement of a fragment of mouse chromosomes 4 and 13 in beta-CCM-induced seizures in a previous paper. Here, we analyzed, through [3H]-flumazenil binding, whether central BZD binding sites could be involved in the physiological processes underlying these differences of genetic sensitivities. In the JE/Le strain, where the effects of the chromosome 4 fragment can be analyzed, we found associations between [3H]-flumazenil binding and the convulsive action of beta-CCM. On the contrary, this no longer holds true in C3XtEso strain, where the effects of the chromosome 13 fragment were observed.

Whole blood serotonin and plasma beta-endorphin in autistic probands and their first-degree relatives.

BACKGROUND: Whole blood serotonin (5-HT) and C-terminally directed beta-endorphin protein immunoreactivity (C-ter-beta-EP-ir) are known to be elevated in autistic subjects and might be possible markers of genetic liability to autism. This study thus investigates the familial aggregation of 5-HT and of C-ter-beta-EP-ir levels in first degree relatives of autistic probands. METHODS: In a sample of 62 autistic subjects and 122 of their first-degree relatives, compared to age and sex-matched controls, we measured 5-HT by radioenzymology and C-ter-beta-EP-ir by radioimmunoassay. RESULTS: We confirm the previously reported familiality of hyperserotoninemia in autism as mothers (51%), fathers (45%) and siblings (87%) have elevated levels of 5-HT, and we reveal presence of elevated levels of C-ter-beta-EP-ir in mothers (53%) of autistic subjects. CONCLUSIONS: Familial aggregation of quantitative variables, such as concentration of neurotransmitters, within unaffected relative could serve as an intermediate phenotype and might thus help the search of genetic susceptibility factors in autism.

Genetic factors regulate processes related to anxiety in mice.

The propensity for anxiety-related behavior has been studied by comparing two highly inbred strains of mice, ABP/Le and C57BL/6ByJ, in two behavioral procedures, open-field and light-dark preference. Their Mendelian F2 population allowed us to evaluate the putative involvement of four easily identifiable loci in anxiogenic processes. In fact, chromosomal regions containing the brown, pink-eyed dilution and short-ear loci on the 4th, 7th and 9th chromosomes respectively are associated with anxiety-related behavior patterns. In addition, binding of [3H]flumazenil to brain GABA(A) receptors was measured as a biochemical index that may be associated with observed behavior patterns.

Convulsive effects of a benzodiazepine receptor inverse agonist: are they related to anxiogenic processes?

The linkage-testing strain of ABP/Le mice carries six mutations which express in easily identifiable phenotypes. By crossing this strain with a traditional inbred strain (C57BL/6ByJ) which is the 'wild type' for the mutated ABP/Le loci, we produced Mendelian populations, intercrosses and backcrosses so as to estimate whether the sensitivity to methyl beta-carboline-3-carboxylate (beta-CCM), a benzodiazepine receptor inverse agonist, and anxiety-related behaviour could be related to a common genetically determined substrate. We have shown that one locus on chromosome 9 is associated with beta-CCM-induced seizures and three loci on chromosomes 4, 7 and 9 are associated with anxiogenic processes. Analysis of [3H]flumazenil binding suggested a possible involvement of a Bmax decrease in both beta-CCM-induced seizures and anxiogenic processes. The putative common genetic regulation of both mechanisms is discussed.

A mouse mutant strain highly resistant to methyl beta-carboline-3-carboxylate-induced seizures.

The convulsant properties of methyl beta-carboline-3-carboxylate (beta-CCM) were evaluated in the TaT-fm/GncTa+/+Tfm strain carrying the tabby coat color (Ta) and/or the testicular feminization (Tfm) gene. When injected intraperitoneally within a 5-60 mg/kg dose range, beta-CCM-induced convulsions in less than 25% of the mice, thus providing evidence for a high resistance of this strain, as compared to classical strains of mice. However, this strain responds normally to the convulsant pentylenetetrazol (PTZ), suggesting a specific resistance to beta-CCM. Both the Ta gene and the TaTfm/Gnc genetic background were involved in the high resistance to beta-CCM. In addition, concentrations of neurosteroids and benzodiazepine binding, both modulating GABAA receptor efficacy, have been measured in order to elucidate the biological mechanisms of drug resistance.

Ras involvement in signal transduction by the serotonin 5-HT2B receptor.

The family of serotonin 5-HT2 receptors stimulates the phospholipase C second messenger pathway via the alpha subunit of the Gq GTP-binding protein. Here, we show that agonist stimulation of the 5-HT2B receptor subtype stably expressed in the mouse fibroblast LMTK- cell line causes a rapid and transient activation of the proto-oncogene product p21ras as measured by an increase in GTP-bound Ras in response to serotonin. Furthermore, 5-HT2B receptor stimulation activates p42mapk/p44mapk (ERK2/ERK1) mitogen-activated protein kinases as assayed by phosphorylation of myelin basic protein. Antibodies against p21ras, Galphaq, -beta, or -gamma2 subunits of the GTP-binding protein inhibit MAP kinase-dependent phosphorylation. The MAP kinase activation is correlated with a stimulation of cell division by serotonin. In addition to this mitogenic action, transforming activity of serotonin is mediated by the 5-HT2B receptor since its expression in LMTK- cells is absolutely required for foci formation and for these foci to form tumors in nude mice. Finally, we detected expression of the 5-HT2B receptor in spontaneous human and Mastomys natalensis carcinoid tumors and, similar to the 5-HT2B receptor transfected cells, the Mastomys tumor cells are also responsive to serotonin with similar coupling to p21ras activation.

Low-dose naltrexone effects on plasma chemistries and clinical symptoms in autism: a double-blind, placebo-controlled study.

The effect of month-long naltrexone (NTX) treatment at a daily oral dose of 0.5 mg/kg/day was contrasted with placebo (PLC) in a double-blind study with conjoint clinical and biochemical evaluations of therapeutic effects. Modest clinical benefits were achieved with both PLC and NTX, with marginally better overall results following NTX, and degree of improvement appeared to be related to plasma chemical profiles. Massively elevated levels of beta-endorphin were observed in all children with assays using C-terminal antibody but not with an N-terminal antibody assay. In addition, 70% of the children exhibited abnormally low levels of adrenocorticotropic hormone, and smaller subsets exhibited elevated norepinephrine (60%), arginine-vasopressin (50%), and serotonin (20%). The best clinical responders exhibited the clearest normalization of the elevated plasma chemistries, especially in C-terminal-beta-endorphin and serotonin. There was some evidence of therapeutic carry-over effects in both clinical and biochemical measures in those children who received NTX before PLC. The results suggest that NTX only benefits a subgroup of autistic children, who may be identified by the presence of certain plasma abnormalities. These results suggest a possible linkage between abnormal plasma chemistries, especially those related to the pro-opiomelanocortin system, and autistic symptoms.

Difference between plasma N- and C-terminally directed beta-endorphin immunoreactivity in infantile autism.

OBJECTIVE: The authors investigated whether there is excessive opioid activity in infantile autism by measuring plasma beta-endorphin in patients with autism compared with patients who had Rett's syndrome and normal comparison subjects. METHODS: Radioimmunoassays for beta-endorphin using C-terminally and N-terminally directed antisera were applied to plasma samples from 67 children who met both DSM-III-R and ICD-10 diagnostic criteria for infantile autism, 22 girls with Rett's syndrome, and 67 normal children matched in age and sex with the children with autism. RESULTS: Median N-terminally directed beta-endorphin immunoreactivity appeared to be slightly lower in subjects with autism (7 pg/ml) and clearly higher in the girls with Rett's syndrome (40 pg/ml) than in the comparison subjects (9 pg/ml). Median C-terminally directed beta-endorphin immunoreactivity was higher in the girls with Rett's syndrome (35 pg/ml) and much higher in patients with autism (70 pg/ml) than in comparison subjects (8 pg/ml). CONCLUSIONS: These findings demonstrate the existence of a wide discrepancy between C- and N-terminally directed beta-endorphin immunoreactivity among children with autism. Despite the fact that the nature of the antigen recognized in the plasma of autistic children by the C-terminally directed anti-beta-endorphin serum remains to be characterized, the difference between C- and N-terminally directed beta-endorphin immunoreactivity might suggest an abnormal processing of the pro-opiomelanocortin gene in infantile autism.

Serotonin receptors and therapeutics.

Since its discovery, serotonin (5-hydroxytryptamine = 5-HT) has become a major player on the neurotransmitter "stage". Multiple receptor subtypes for 5-HT have been identified and classified, and a vast pharmacology of 5-HT has emerged. In particular, 5-HT has been shown to exert marked effects on the cardiovascular system, central nervous system (CNS) and gastrointestinal (GI) tract, and important ligands have been developed that mimic or block its action selectively. Furthermore, drugs that release 5-HT, and others that prevent its uptake, have been developed. This brief review focuses on the pharmacology of 5-HT agonists and antagonists that exhibit, at least partly, clinical relevance.

Increase of human platelet serotonin uptake by atypical histamine receptors.

Histamine and the guanosine 3',5'-cyclic monophosphate (cGMP)-inducing agent sodium nitroprusside both increased serotonin (5-HT) uptake and cGMP levels in isolated human platelets in vitro. Histaminergic stimulation was observed at concentrations ranging from 10 nM to 0.25 microM [mean effective concentration (EC50) = 0.1 microM histamine]. The inhibition produced by the H2-receptor antagonists tiotidine, metiamide, and cimetidine was 10-10(5) times more potent on histamine receptors regulating 5-HT uptake and cGMP generation in human platelets than on the histaminergic receptors H1, HIC, H2, and H3 in other tissues. The in vitro histamine-induced 5-HT uptake was prevented by preincubation of isolated human platelets in the presence of the nitric oxide synthase inhibitor NG-monomethyl-L-arginine or the cGMP-lowering agent LY-83583. Histamine was ineffective in stimulating cAMP generation in human platelets and did not interact with effector sites known to downregulate 5-HT uptake, including imipramine, gamma-aminobutyric acid A, peripheral type benzodiazepine-binding sites, and V1a vasopressin receptors inducing human platelet shape change and aggregation. These atypical human platelet histaminergic receptors differ from the previously classified histamine receptors by their apparent high affinity to histamine H2-receptor antagonists and their apparent link with the soluble, nitric oxide-dependent guanylate cyclase. These findings suggest that human platelets express a new subtype H2h of histamine receptors.

[Opiate hypothesis in infantile autism? Therapeutic trials with naltrexone]. / Une hypothèse opiacée dans l'autisme infantile? Essais thérapeutiques avec la naltrexone.

The opioid hypothesis suggests that childhood autism may result from excessive brain opioid activity during neonatal period which may constitutionally inhibit social motivation, yielding autistic isolation and aloofness (Panksepp, 1979). This hypothesis has now received strong support and is currently based on three types of arguments: (1) similarity between autistic symptomatology and abnormal behaviors induced in young animals by injections of exogenous opioids, such as increasing social aloofness and decreasing social vocalization; (2) direct biochemical evidence of abnormalities of peripheral endogenous opioids being reported in autism and (3) therapeutic effects of the long lasting opioid receptor blocking agent naltrexone in autism. In this article, we give description of open and double-blind studies of naltrexone in autism. Naltrexone has been tested in several open studies. We performed an open trial with naltrexone in 2 autistic girls, displaying serious self-injurious behavior, reduced crying and a marked preference for salty and spicy foods, symptoms that could be related to a dysfunction of the opioid system. With dosages of 1 mg/kg/day, we observed an immediate reduction of hyperactivity, self-injurious behavior and aggressiveness, while attention improved. In addition, social behaviors, smiling, social seeking behaviors and play interactions increased (Leboyer, Bouvard et Dugas, 1988). Campbell et al. (1988) has also reported a tranquilizing and a stimulating effect in 6 out of 8 children with autism. We did confirm these preliminary results in a double-blind study performed on 4 children with autism. In a cross-over double-blind study, three dosages of naltrexone (0.5, 1 and 2 mg/kg/day) and placebo were compared.(ABSTRACT TRUNCATED AT 250 WORDS)

Metabolism of 6-fluoro-DL-tryptophan and its specific effects on the rat brain serotoninergic pathway.

We administered 6-fluoro-DL-tryptophan (6F-Trp) to rats (50-200 mg/kg i.p.) and evaluated its neurochemical effects on central catechole and indole compounds; we also determined the time course of its action, together with its metabolism and kinetics in four rat brain areas. Neither norepinephrine nor dopamine and its major metabolites were affected by 6F-Trp. With regard to serotonin (5-HT), 6F-Trp induced a transient depletion in all the brain areas studied, with a maximum of about 60-65% obtained between 1 and 3 hr depending on the dose administered. After 6 hr, 5-HT levels generally returned to control values. 5-Hydroxyindolacetic acid (5-HIAA) levels were also reduced 3 hr after administration (-40 to -60%). A large dose-dependent increase in tryptophan (Trp) was observed in the four brain areas, possibly because of an inhibition of Trp incorporation into protein, as suggested by experiments with mouse neuroblastoma cells. The brain elimination half-life of 6F-Trp was estimated at 0.5-1 hr. Regarding 6F-Trp metabolism, three new compounds were detected in all four brain areas after 6F-Trp administration. They were identified by means of liquid chromatography with electrochemical detection and/or radioenzymology, in comparison with fluorinated standards, or after NSD 1015 or pargyline coadministration with 6F-Trp. The first two 6F-Trp metabolites detected were probably 6-fluoro-5-hydroxytryptophan and 6-fluoro-5-HIAA. The third, identified and quantified by means of the two analytical methods, was 6-fluoro-5-HT (6F-5-HT). These findings suggest that 6F-Trp could be used as the in vivo precursor of 6F-5-HT with a view to tracing neuronal serotoninergic pools, as has already been done with platelets.

Genetic difference in sensitivity to beta-carboline: evidence for the involvement of brain benzodiazepine receptors.

The convulsive effects of methyl beta-carboline-3-carboxylate (beta-CCM), a benzodiazepine receptor ligand, are different in two inbred strains of mice: BALB/cBy mice are more sensitive to beta-CCM than C57BL/6J mice. In the present article, we report the effects of [3H]flunitrazepam binding in these two strains, which suggest a possible explanation of the differences in their sensitivity to beta-CCM by the involvement of brain benzodiazepine receptors.

Serotonin metabolism and other biochemical parameters in infantile autism. A controlled study of 22 autistic children.

The serotonin metabolism was extensively studied in 22 couples of autistic children and age- and sex-matched controls. Histamine, calcium, and uric acid were also measured in urine and whole blood or plasma. Autistics and controls did not differ in histamine, and only minor changes were noticed in calcium content. According to previous reports, serotonin levels were often, but not always, elevated in the blood of autistic children. Based on data including urinary serotonin and 5-hydroxyindoleacetic acid, platelet serotonin uptake and efflux, platelet monoamine oxidase and glutathione peroxidase activities, and uric acid and plasma tryptophan, the origin(s) of such hyperserotonemia in autism appear(s) to be of metabolic origin, i.e., a decreased catabolism and/or an increased biosynthesis of serotonin.

Biochemical and pharmacological characterization of histamine-mediated up-regulation of human platelet serotonin uptake. Evidence for a subclass of histamine H2 receptors (H2h) highly sensitive to H2 receptor antagonists.

The stimulatory effect of histamine: H (1.2 to 3-fold increase) on serotonin (5-HT) uptake by human platelets was observed after a 5 min incubation period in the presence of 2.5 X 10(-7) M histamine, followed by subsequent 5 min incubation of the platelets with 10(-7) M [3H] 5-HT. Methyl, ethyl and acetyl substituents in the side chain of H mimicked the stimulatory effect of H. In contrast, H analogs methylated at the position N-1 of the imidazole ring of H, as well as imidazole and histidine inhibited platelet 5-HT uptake. The cAMP-inducing agents forskolin and theophylline have no effect on 5-HT uptake when they are tested alone or in combinations with H. In contrast, the cGMP-inducing agent sodium nitroprusside (10(-7) M-10(-6) M) stimulated and potentiated H-mediated up-regulation of 5-HT uptake. Histamine H2 receptor agonists and antagonists are more potent than drugs acting on H1 receptors (H2 greater than H1). However, the inhibition constants Ki are not consistent with those determined for typical H1, H2, H3 receptors characterized in other tissues. This findings provide further evidence for the existence of multiple forms of H receptors and suggest the involvement of a subpopulation of H2 receptors, highly sensitive to H2 receptor antagonists (H2h), mediating 5-HT uptake in human platelets.