Glucose transport and utilization are altered in the brain of rats deficient in n-3 polyunsaturated fatty acids

Long-chain polyunsaturated (n-3) fatty acids have been reported to influence the efficiency of membrane receptors, transporters and enzymes. Because the brain is particularly rich in docosahexaenoic acid (DHA, 22:6 n-3), the present study addresses the question of whether the 22:6 n-3 fatty acid deficiency induces disorder in regulation of energy metabolism in the CNS. Three brain regions that share a high rate of energy metabolism were studied: fronto-parietal cortex, hippocampus and suprachiasmatic nucleus. The effect of the diet deficient in n-3 fatty acids resulted in a 30-50% decrease in DHA in membrane phospholipids. Moreover, a 30% decrease in glucose uptake and a 20-40% decrease in cytochrome oxidase activity were observed in the three brain regions. The n-3 deficient diet also altered the immunoreactivity of glucose transporters, namely GLUT1 in endothelial cells and GLUT3 in neurones. In n-3 fatty acid deficient rats, GLUT1-immunoreactivity readily detectable in microvessels became sparse, whereas the number of GLUT3 immunoreactive neurones was increased. However, western blot analysis showed no significant difference in GLUT1 and GLUT3 protein levels between rats deficient in n-3 fatty acids and control rats. The present results suggest that changes in energy metabolism induced by n-3 deficiency could result from functional alteration in glucose transporters.     

Direct cocktail analysis of drug discovery compounds in pooled plasma samples using liquid chromatography-tandem mass spectrometry

Direct plasma injection technology coupled with a LC-MS/MS assay provides fast and straightforward method development and greatly reduces the time for the tedious sample preparation procedures. In this work, a simple and sensitive bioanalytical method based on direct plasma injection using a single column high-performance liquid chromatography (HPLC) and tandem mass spectrometry (MS/MS) was developed for direct cocktail analysis of double-pooled mouse plasma samples for the quantitative determination of small molecules. The overall goal was to improve the throughput of the rapid pharmacokinetic (PK) screening process for early drug discovery candidates. Each pooled plasma sample was diluted with working solution containing internal standard and then directly injected into a polymer-coated mixed-function column for sample clean-up, enrichment and chromatographic separation. The apparent on-column recovery of six drug candidates in mouse plasma samples was greater than 90%. The single HPLC column was linked to either an atmospheric pressure chemical ionization (APCI) or electrospray ionization (ESI) source as a part of MS/MS system. The total run cycle time using single column direct injection methods can be achieved within 4 min per sample. The analytical results obtained by the described direct injection methods were comparable with those obtained by semi-automated protein precipitation methods within +/- 15%. The advantages and challenges of using direct single column LC-MS/MS methods with two ionization sources in combination of sample pooling technique are discussed.     

Molecular basis of bacterial virulence and survival within infected hosts and the environment

The EMBO–FEBS lecture course on the ‘Molecular Basis of Bacterial Virulence and Survival Within Infected Hosts and in the Environment’, organized by Pascale Cossart, Efstathios Gonos and Roberto Kolter, was held on the island of Spetsai, Greece, September 3–13, 2002.     

Differential channelling of liver lipids in relation to susceptibility to hepatic steatosis in two species of ducks

In the human, hepatic steatosis can be associated with an imbalance between synthesis, secretion and storage of hepatic lipids, and exhibits a genetic susceptibility. The effect of overfeeding on hepatic lipid channelling was investigated in two genotypes of ducks that differ in their susceptibility to fatty liver, i.e. the common duck, Anas platyrhynchos, and the Muscovy duck, Cairina moschata. Before overfeeeding, the Muscovy duck exhibited a lower subcutaneous adiposity and a higher muscular development, whereas hepatic composition was similar in both genotypes (>5% lipids and triglycerides accounting for 6–10% lipids). In the plasma lipoprotein profile, HDL predominated (5.5–7.8 g/l) over VLDL (0.09–0.25 g/l) and LDL (0.65–1.06 g/l). All lipid and lipoprotein concentrations were lower in the Muscovy duck. In response to overfeeding, the Muscovy duck exhibited a higher degree of hepatic steatosis (62 vs. 50% lipids), and a lower increase in adiposity and in the concentration of plasma triglycerides (6-fold vs. 10-fold) and VLDL (23-fold vs. 34-fold). Thus, certain genotypes may be more responsive to the dietary induction of fatty liver because of a less efficient channelling of hepatic lipids towards secretion into plasma and adipose storage, and the duck may represent a suitable model in which to study the development of hepatic steatosis and its pathogenesis.     

Retentissement sexuel, conjugal et social d’une population d’hommes stériles consultants en Andrologie: le point de vue du psychiatre de liaison

Material and methods

The study population consisted of 39 subjects divided into two groups: 21 azoospermic males and 18 oligoazoospermic males. These men were selected in andrology departments over a period of six months. The andrology and liaison psychiatry departments of Lille university hospital established a general infertility questionnaire. This semi-structured questionnaire comprising 40 questions was based on clinical experience and describes the clinical and symptomatic context of infertility. An individual 50-item questionnaire was then used to analyse the psychosocial, marital and sexual effects of male infertility and the representation of the psychiatrist in the andrology department.

Results

One third of patients discovered the diagnosis of infertility when the biologist gave them the results of the semen analysis. Our patients initially envisaged marital, psychological and social problems, but very few sexual problems. They imagined that infertility was more disturbing for women than for men, from a psychological and sexual point of view. 82% of our subjects imagined that their partner had no sexual problems. 48.7% of them thought that their partner had no psychological difficulties related to their infertility. The oligoasthenospermia group considered that the partner had significantly more “psychological difficulties” compared to the azoospermia group. 41% of our patients felt guilty towards their partner because of their infertility diagnosis. 10.3% of patients presented sexual disorders before the diagnosis of male infertility and 25.6% presented sexual disorders after this diagnosis. Contrary to data in the literature, a major change of sexuality was not observed in the majority of the couples after the diagnosis. When sexuality changed, it generally consisted of a reduction of the frequency of sexual relations. Among the patients who reported sexual difficulties, only 40% related them to infertility. 50% did not report any relationship between the psychological difficulties related to infertility and the sexual difficulties. Contrary to the data in the literature, neither the loss of spontaneity during sexual relations, nor the complementary investigations necessary for artificial insemination had any influence on sexuality. 89.8% of our patients are ready to change their sexual practices in order to be more fertile without causing any sexual or psychological problems. However, only 34.3% of patients reported a concern about reproductive efficacy during sexual relations. A more marked sexuality/reproduction dissociation was observed in oligoazoospermic males than in azoospermic males. 28.2% of patients reported that talking about their sexual and/or psychological problems with a psychiatrist was helpful.

Conclusion

Many contradictions and underestimations were observed in the answers to the questions. We confirmed the existence of a psychological and sexual distress, but which was quantitatively less severe than that described in “gynaecological” populations. However, a real psychological and sexual distress does exist in our population, which is why we propose from the outset a psychosomatic and sexological treatment of infertility in order to prevent the onset of these sexual difficulties. Our questionnaire was based on clinical experience and helped our patients to identify their psychological and sexual difficulties related to infertility and its treatment. It would therefore be useful for the practitioner, andrologist or psychiatrist, to help the patient express the effects related to this “new medicalized sexuality”.     

Characterization of carbonic anhydrases from Riftia pachyptila,a symbiotic invertebrate from deep-sea hydrothermal vents

The symbiotic hydrothermal vent tubeworm Riftia pachyptila needs to supply its internal bacterial symbionts with carbon dioxide, their inorganic carbon source. Our aim in this study was to characterize the carbonic anhydrase (CA) involved in CO(2) transport and conversion at various steps in the plume and the symbiotic tissue, the trophosome. A complete 1209 kb cDNA has been sequenced from the trophosome and identified as a putative alpha-CA based on BLAST analysis and the similarities of total deduced amino-acid sequence with those from the GenBank database. In the plume, the putative CA sequence obtained from cDNA library screening was 90% identical to the trophosome CA, except in the first 77 nucleotides downstream from the initiation site identified on trophosome CA. A phylogenetic analysis showed that the annelidan Riftia CA (CARp) emerges clustered with invertebrate CAs, the arthropodan Drosophila CA and the cnidarian Anthopleura CA. This invertebrate cluster appeared as a sister group of the cluster comprising mitochondrial and cytosolic isoforms in vertebrates: CAV, CAI II and III, and CAVII. However, amino acid sequence alignment showed that Riftia CA was closer to cytosolic CA than to mitochondrial CA. Combined biochemical approaches revealed two cytosolic CAs with different molecular weights and pI's in the plume and the trophosome, and the occurrence of a membrane-bound CA isoform in addition to the cytosolic one in the trophosome. The physiologic roles of cytosolic CA in both tissues and supplementary membrane-bound CA isoform in the trophosome in the optimization of CO(2) transport and conversion are discussed.