Extracellular Events Induced by γ-Hydroxybutyrate in Striatum: A Microdialysis Study

The modification of dopamine release and accumulation induced by gamma-hydroxybutyrate (GHB) was studied using both striatal slices and in vivo microdialysis of caudate-putamen. GHB inhibited dopamine release for approximately 5-10 min in vitro, and this was associated with an accumulation of dopamine in the tissue. Subsequently, there was an increase in dopamine release. In the microdialysis experiments, low doses of GHB inhibited dopamine release, whereas higher doses strongly increased release; the initial decrease seen in slices could not be detected in vivo. Thus, GHB had a biphasic effect on the release of dopamine: An initial decrease in the release of transmitter was followed by an increase. A time-dependent biphasic effect was observed when GHB was added to brain slices, and a dose-dependent biphasic effect was seen in dialysate after systemic administration of GHB. Naloxone blocked GHB-induced dopamine accumulation and release both in vitro and in vivo. GHB also increased the release of opioid-like substances in the striatum. A specific antagonist of GHB receptors completely blocked both the dopamine response and the release of opioid-like substances. These data suggest that GHB increases dopamine release via specific receptors that may modulate the activity of opioid interneurons.     

Iodine intakes assessed by urinary iodine concentrations in healthy children aged ten months,two years,and four years

Urinary iodine excretion was assessed in 642 healthy children aged 10 mo (n=243), 2 yr (n=183), and 4 yr (n=216) living in the Paris area and originating from continental France (60.3%), North Africa (13.8%), the West Indies (9.1%), West Africa (8.3%), Southeast Asia (4.8%), and southern Europe (3.8%). Mild impairment of neurological (reflexes, tone, audiometry) and intellectual development (Brunet-Lézine scale) was assessed in relation to iodine status. Iodine excretions (median values) were 18.4, 11.9, and 10.9 μg/100 mL at 10 mo, 2 yr, and 4 yr, respectively, and risk of mild iodine deficiency (5–10 μg/100 mL) was 18.1%, 34.8%, and 38.3% for the same age groups. No relationship was found between anthropometry, global development quotient, and iodine status. High hearing thresholds were more commonly associated with lower iodine excretion, suggesting mild hearing defects. In spite of iodine prophylaxis, the risk of mild to moderate iodine deficiency still exists in France and in a number of European countries. Evaluation of neurological sequels of borderline iodine status is a major public health problem in European communities.     

Interleukin 2 production in iron-deficient children

The relationship between iron status and capacity for IL-2 production by lymphocytes was assessed in 81 children from 6 mo to 3 yr of age selected at random from a population with low socioeconomic status, undergoing free systematic examination in four children's health centers in the Paris area. Iron deficiency was defined by the existence of at least two abnormal values among the three indicators of iron status: serum ferritin level ≤12 μg/L, transferrin saturation <12%, and erythrocyte protoporphyrin concentration >3 μg/g hemoglobin. According to this definition, 53 children were classified as iron deficient and 28 as iron sufficient. No differences were observed between the iron-deficient and iron-sufficient groups in terms of the IL-2 concentration without stimulation by PHA. IL-2 production by lymphocytes stimulated with PHA, as well as the stimulation index (ratio of IL-2 concentration following stimulation by PHA to that of IL-2 concentration without stimulation by PHA) were significantly lower in iron-deficient children. The reduction in IL-2 production by activated lymphocytes observed in our study of iron-deficient children may be responsible for impairments in immunity found by other authors, particularly in cell-mediated immunity.     

The xylanase introns from Cryptococcus albidus are accurately spliced in transgenic tobacco plants

The xylanase gene from Cryptococcus albidus contains seven introns. Genomic and cDNA clones under the control of the CaMV 35S promoter were transferred into tobacco plants using Agrobacterium-mediated cell transformation. The genes were transcribed and the mRNAs were amplified by the polymerase chain reaction using primers on each side of the intron region. About 90% of the amplification products from plants transformed with the genomic clone corresponded to the size of the pre-mRNA (1.2 kb) and 10% represented the spliced product (0.85 kb). The 0.85 kb fragment was cloned and sequenced and the result indicated that the introns from the xylanase gene were accurately spliced by the plant cells.     

Fractionation of subcellular membranes of the secretory pathway from the peroxidase-producing white-rot fungus Phanerochaete chrysosporium

Abstract Mycelia from the basidiomycete Phanerochaete chrysosporium , producing lignin and manganese peroxidases, were homogenized and fractionated on a sucrose gradient. The main subcellular fungal membrane fractions were successfully separated. Lipid composition analyses of the isolated membranes as well as associated marker enzymes distribution gave evidence to similarities with membranes originating from plants. Lignin and manganese peroxidases were investigated by immunodetection in subcellular fractions. Our results show that lignin and manganese peroxidases are mainly associated with Golgi apparatus vesicles and, to a lesser extent, with endoplasmic reticulum and light density vesicles, but not with plasma membranes.     

A Chemical Proteomics Approach for the Search of Pharmacological Targets of the Antimalarial Clinical Candidate Albitiazolium in Plasmodium falciparum Using Photocrosslinking and Click Chemistry

Plasmodium falciparum is responsible for severe malaria which is one of the most prevalent and deadly infectious diseases in the world. The antimalarial therapeutic arsenal is hampered by the onset of resistance to all known pharmacological classes of compounds, so new drugs with novel mechanisms of action are critically needed. Albitiazolium is a clinical antimalarial candidate from a series of choline analogs designed to inhibit plasmodial phospholipid metabolism. Here we developed an original chemical proteomic approach to identify parasite proteins targeted by albitiazolium during their native interaction in living parasites. We designed a bifunctional albitiazolium-derived compound (photoactivable and clickable) to covalently crosslink drug–interacting parasite proteins in situ followed by their isolation via click chemistry reactions. Mass spectrometry analysis of drug–interacting proteins and subsequent clustering on gene ontology terms revealed parasite proteins involved in lipid metabolic activities and, interestingly, also in lipid binding, transport, and vesicular transport functions. In accordance with this, the albitiazolium-derivative was localized in the endoplasmic reticulum and trans-Golgi network of P. falciparum. Importantly, during competitive assays with albitiazolium, the binding of choline/ethanolamine phosphotransferase (the enzyme involved in the last step of phosphatidylcholine synthesis) was substantially displaced, thus confirming the efficiency of this strategy for searching albitiazolium targets.