Angiosperm Gymnostoma trees produce root nodules colonized by arbuscular mycorrhizal fungi related to Glomus.

• Structure and fungal composition is presented here for 'mycorrhizal' nodules of two angiosperms of the genus Gymnostoma (Casuarinaceae), G. deplancheanum and G. nodiflorum. These species are endemic to New Caledonia, where they grow on ultramafic soils. The mycorrhizal nodules, which are modified lateral roots invaded by an arbuscular mycorrhizal fungus, occur in addition to N2 -fixing nodules. • Techniques included PCR amplification of extracted DNA, for species identification, and histological studies to compare the developmental pathway of Gymnostoma mycorrhizal nodules with that of actinorhizal nodules. • The fungal DNA suggested that the strain belongs to the genus Glomus (Glomales). The endophytic mycelium also contained typical Glomus arbuscules and hyphal coils. Structurally, Gymnostoma mycorrhizal nodules are similar to those described in some Coniferales and in Caesalpinioideae trees of French Guyana. • The mycorrhizal nodules of G. deplancheanum and G. nodiflorum contain a fungus belonging to the Glomales. The role of the nodules might be linked to the ecological situation of the host plants, which are pioneers in exposed and rocky habitats.

Surgical treatment of morbid obesity with biliopancreatic diversion and gastric banding: report on an 8-year experience involving 235 cases.

STUDY AIM: Developments have recently been made in bariatric surgery outside the USA. The aim of this retrospective non-randomized study was to report on our experience regarding biliopancreatic diversion (BPD) and non-adjustable gastric banding (GB) in a population of 235 obese patients. PATIENTS AND METHODS: From March 1990 to March 1998, 235 obese patients were operated on, 142 by BDP and 93 by GB, via laparotomy after rigourous selection of the patient population. RESULTS: The mean duration of surgery was 2 h 50 minutes for BPD and 1 h for GB. One postoperative death occurred due to massive pulmonary embolism. Early major complications were frequent in the BPD group (n = 21) but rare in the GB group (n = 1). Mean duration of hospitalization was 16 days in the BPD group versus 9 days in the GB group. Mean percentage excess weight loss was 48% for the GB group and 60% for the BPD group after two years. Late mortality was limited to the BPD group (3.5%). Late complications were evenly distributed between the two groups, with a prevalence of malnutrition in the BPD group and outlet stenosis in the GB group. A high incidence of band removal was recorded related to this complication (17.2%). Incisional hernias were present in both groups. CONCLUSIONS: GB and BPD are techniques which can induce weight loss and bring about subsequent health benefits. Nevertheless, in a few patients further intervention or adaptation of the approach due to clinical failure or to a high complication rate is required. Additional research is needed regarding determination of the surgical treatment that is best adapted to the case in question, i.e., taking into consideration both the restrictive and malabsorbative aspects.

Effects of serotonin-selective and classical antidepressants on the auditory P300 cognitive potential.

The cognitive potential, P300, is a phenomenon frequently studied in relation to template matching of the brain. To understand the neurochemical mechanisms of its generation, we compared the effects of three antidepressants, fluoxetine, tianeptine and clomipramine after single and repeated application as well as after 1 week of withdrawal on the P300 and N200 waves in an auditory 'odd-ball' paradigm in three parallel groups of 10 healthy volunteers. Following single administration, both fluoxetine and clomipramine reduced (-39 +/- 14%, p < 0.01) the peak amplitude of P300 at the Pz electrode. For fluoxetine and tianeptine, reduced amplitudes of 19 +/- 7% and 24 +/- 11%, respectively, were found following 8 days of treatment, 2 h after administration. However, for clomipramine no additional diminution was found on day 8 with respect to day 1. Topographic distributions tended to be significantly modified at the frontal scalp area 1 h after the tianeptine administration on day 8, whereas the postdosing changes induced by fluoxetine were localised in the midline and right centrotemporal scalp regions. Only minor reductions in peak latencies have been observed. It can be concluded that serotonin selective drugs have a slower onset of P300 amplitude decrease than clomipramine, which has additional effects on monoaminergic and on cholinergic systems. These results suggest that serotonin has a regulatory function in the neurotransmission of cerebral structures which are involved in the evaluation of stimulus relevance.

Electroencephalographic characterization of brain dopaminergic stimulation by apomorphine in healthy volunteers.

Apomorphine, a dopamine receptor agonist (given in a dose of 0.75 mg s.c.), was administered to 8 healthy volunteers; electroencephalograph (EEG) and event-related potential (ERP) mapping were performed before dosing and 0.5, 1.5 and 2.5 h after dosing. Apomorphine caused an overall increase in beta activity at time 0.5 h in both absolute and relative energy; P300 and CNV ERPs were not significantly altered, although a tendency towards increased P300 latency was seen. The results confirm that the EEG mapping technique is sufficiently sensitive to monitor dopaminergic neurochemical stimulation by means of apomorphine. This could lead to a new, non-invasive and repeatable method for monitoring central neuronal systems which is more convenient to apply repeatedly than for example positron emission tomography techniques. Furthermore, electrophysiological techniques undoubtedly constitute an alternative to classical neuroendocrinological methods, allowing a more direct assessment of central nervous system neurotransmission. Finally, these EEG approaches could lead to better characterization of drugs acting on dopaminergic pathways, such as antipsychotics.

Distribution of gymnostoma spp. microsymbiotic frankia strains in new caledonia is related to soil type and to host-plant species

The diversity of the Frankia strains that are naturally in symbiosis with plants belonging to the Gymnostoma genus in New Caledonia was investigated. A direct molecular characterization of DNA extracted from nodules was performed, followed by characterization by restriction fragment length polymorphism (RFLP) of the ribosomal rrs-rrl (16S-23S) intergenic spacer (IGS) polymerase chain reaction (PCR)-amplified region. Seventeen different patterns were identified among the 358 microsymbiotic strains studied in the eight species of host plant present in New Caledonia. This genotypical approach permitted us to show that a large diversity existed among the patterns and that these did not exhibit a strict specificity to any host-plant species comparable with that previously found in the Casuarina and Allocasuarina symbioses in Australia. Despite this lack of specificity, a correspondence analysis nevertheless showed that the distribution of these patterns was related to soil type and to host-plant species. Furthermore, several Frankia strains were exclusively associated with the ultramafic soils.

Pharmacoelectroencephalographic profile of befloxatone, a new reversible MAO-A inhibitor, in healthy subjects.

The pharmaco-EEG profile and the effects on P300 and CNV of befloxatone, a new selective and reversible MAO-A inhibitor, were assessed in a randomized, double-blind, placebo-controlled, 4-way crossover study. Twelve healthy young male volunteers were administered single doses of 2.5, 10 and 20 mg befloxatone and placebo separated by a 1-week washout. The EEG data were recorded before and at least 6 h after drug administration, by means of 28 leads allowing topographical analysis of the results. MAO inhibition, subjective effects and safety variables were also investigated. Statistical analysis was performed by means of the SDT method. Befloxatone induced dose-related EEG changes which occurred rapidly, peaked between 0.5 and 2 h and lasted at least until 6 h after drug administration. The EEG changes were characterized by an increase in absolute and/or relative alpha power, mainly alpha 1, after the 3 doses and a theta power increase after 10 and 20 mg only. These changes occurred mainly over the centroparietotemporal areas. Concerning the event-related potential, P300 latency of the auditory evoked potentials did not change. The P300 and CNV mean topographic amplitudes were decreased, between 0.5 and 2 h, after the two lowest doses for the P300 and the 3 doses for the CNV. After administration of 2.5, 10 and 20 mg, MAO inhibitions was shown by respectively 38, 76 and 81% reduction in plasma free 3, 4-dihydroxyphenylglycol reached after 2-4 h. Such a pharmaco-EEG profile, occurring at doses inducing MAO-A inhibition, is similar to those already described with nonsedative antidepressants.

Statistical Decision Tree: a tool for studying pharmaco-EEG effects of CNS-active drugs.

Quantitative pharmaco-EEG has become a useful technique for determining pharmacodynamic parameters after CNS-active drug administration. Nevertheless, one of the most important problems faced by practitioners of pharmaco-EEG is the difficulty in evaluating drug-specific effects. In this article, a methodology for comparing two time sequences of pharmacodynamic measurements, the Statistical Decision Tree (SDT), is proposed. This methodology, based on one- and multi-dimensional Wilcoxon signed-rank tests on EEG variables, takes into account vigilance fluctuations and placebo effects in order to pick out effects specifically due to the drug.

Enzyme polymorphism of Azorhizobium strains and other stem- and root-nodulating bacteria isolated from Sesbania rostrata.

Relationships between bacterial groups nodulating Sesbania rostrata were evaluated through examination of electrophoretic polymorphism of esterases and metabolic enzymes. The following conclusions were drawn: (i) the differentiation of two genomic species within Azorhizobium strains and a group of non-identified strains (probably Rhizobium) was strongly supported by enzyme electrophoresis; (ii) esterases were more electrophoretically polymorphic than metabolic enzymes, since 35 and 11 electrophoretic types, respectively, were detected within the 57 strains studied; (iii) strains isolated from stem or root nodules were genetically very similar and could not be differentiated; (iv) six Azorhizobium strains isolated from plants growing in saline soils could not be grouped separately from the other strains, which might be attributed to the adaptation of azorhizobia to epiphytic conditions; and (v) a comparative study of esterase patterns of azorhizobia showed that strains isolated in the Philippines probably originated in northern Senegal, but did not reveal a clear separation between strains originating from northern and central Senegal.

[Taxonomic study of free nitrogen-fixing bacteria isolated from the endorhizosphere of rice]. / Etude taxonomique de bactéries azotofixatrices libres isolées de l'endorhizosphère du riz.

Twenty strains of free-living N2-fixing bacteria, isolated from the endorhizosphere of rice in rice soils of Senegal, were studied on the basis of 259 morphological, physiological, biochemical and nutritional characters. Half of them were Gram-negative small rods with polar flagella and showing a strictly respiratory metabolism; they were characteristic of the genus Pseudomonas. A first group of 6 strains was related to the P. cepacia-P. marginata group characterized by lophotrichous flagella; they accumulated polyhydroxybutyrate, assimilated arginine and betaine, grew at 41 degrees C and showed a wide nutritional spectrum with DNA GC% of 67-68. The second group of 4 strains was related to the P. lemoignei group because of (a) its monotrichous flagella, (b) poly-beta-hydroxybutyrate accumulation, (c) failure to assimilate arginine and betaine and to grow at 41 degrees C, (d) lack of arginine dihydrolase and (e) its narrow nutritional spectrum. DNA GC% was 65. These 4 strains were also denitrifying bacteria. Six strains were related to the genus Alcaligenes because of their strictly respiratory metabolism and their peritrichous flagella; their nutritional spectrum was variable and one of them was a denitrifier. DNA GC% was 68. One strain was related to Aeromonas hydrophila of the Vibrionaceae family; it consisted of Gram-negative and oxidase-positive small rods with monotrichous polar flagella and respiratory and fermentative metabolism without gas evolution. This strain essentially assimilated sugars and its DNA GC% was 63. Another strain was a Gram- and oxidase-negative small rod with peritrichous flagella and respiratory and fermentative metabolism with gas evolution. Sugars, organic acids and amino acids were assimilated. The DNA GC% was 53. This strain was related to Enterobacter cloacae of the Enterobacteriaceae family, but it showed the additional faculty of denitrification. The last two strains studied were spirilla with amphitrichous flagella characteristic of the genus Aquaspirillum. They showed a strictly respiratory metabolism and a DNA CG% of 60-64. This study allowed us to show the N2-fixing capacity of species of Pseudomonas, Alcaligenes and Aeromonas which had been devoid of N2-fixing bacteria until this time. All strains studied were microaerophilic for N2 fixation.

[Distribution of heterotrophic aerobic microflora and specially denitrifying and free-living nitrogen-fixing bacteria in the rhizosphere of rice (author's transl)]. / Distribution de la microflore hétérotrophe aérobie et en particulier des bactéries dénitrifiantes et fixatrices d'azote libres dans la rhizosphère du riz.

The distribution of heterotrophic aerobic bacteria, actinomycetes and fungi was estimated in three samples (rhizospherical soil (SR), rhizoplane (R) and endorhizosphere (ER)) obtained from one rice seedling which had grown in pot during four mounths in a Casamance grey soil. The number of microbial populations were about the same from one sample to another: 1.1 to 2 X 10(8) bacteria, 3.3 to 8.6 X 10(6) actinomycetes and 0.2 to 8.9 X 10(4) fungi per gram of dry soil (SR) or dry roots (R and ER). The denitrifying and free-living nitrogen fixing bacteria were numerous (10(7) bacteria/g) but lower for ER where the number of actinomycetes remained high. Thirty-six bacterial strains have been isolated from every sample with the use of a grid of isolation. The Gram-negative bacteria were dominant in SR and R where they represented respectively 70 and 94% of total count. The major groups were non-sporulated Gram-variable rods (SR) and Alcaligenes-like bacteria (ER). The pseudomonads represented quite 15% of total count in the three samples. On the other hand, the frequency of endospore-forming Gram-positive bacteria was high only in R where the Bacillus group was estimated to 45% of total count. Only 5 free-living nitrogen-fixing bacterial strains had shown a denitrifying ability.