Progesterone receptor and dopamine synthesizing enzymes in hypothalamic neurons of the guinea pig: an immunohistochemical triple-label analysis

Interactions among gonadal steroid hormones and the dopamine synthesizing enzymes, tyrosine hydroxylase (TH) or aromatic L-amino acid decarboxylase (AADC), participate in hypothalamic functions. Several findings suggest that the expression patterns of the progesterone receptor (PR), TH and AADC overlap in the guinea pig brain. However, it remained to be determined whether or not these two enzymes coexist in the same neurons which contain the PR. To test this hypothesis and quantify these colocalization relationships in the hypothalamus, we used a triple-labeling immunofluorescence procedure. Only PR/AADC-immunoreactive cells were seen in the preoptic area but no PR/TH cells and, therefore, no triple immunoreactive cells were found. An occasional colocalization between PR and the two enzymes was observed throughout the rostrocaudal extent of the arcuate nucleus with the greatest concentration of triple-labeled cells in the medial subdivision. In this region, quantitative estimation of cellular immunoreactivity showed that the triple immunoreactive cells represented about 29% of PR/TH cells, 9% of PR/AADC cells and 22% of TH/AADC cells in spite of a very low percentage in relation to total populations of neurons expressing only PR, TH or AADC. Thus, the PR are only present in monoenzymatic AADC expressing neurons in the preoptic area while they can be observed in neurons expressing both enzymes in the arcuate nucleus.     

Severe Distal Ischemic Syndrome after Buprenorphine Volunteer Intra-arterial Injection

High dosage buprenorphine (HDB) is a sublingual maintenance treatment of opioid dependence which have proved its substantial Public Health results, but it is also known to be frequently abused and diverted, in particular for intravenous injection, with deleterious consequences. Intra-arterial use is more rarely reported with this substance, just like its complications, mainly ischemic, potentially necrotic, phenomena. We report here such a case, with a 30 years-old man suffering from severe ischemia of the thumb, the forefinger and the middle finger few hours after direct injection of a suspension of buprenorphine crushed tablets in right radial arteria. A treatment combining surgery (video-thoracoscopic thoracic sympathectomy) and medicines (heparin, iloprost and piribedil mesilate), permitted a semi-complete digital rehabilitation (only forefinger pulp necrosis persisted and requiried a distal amputation), and the patient was discharged after 2 weeks.     

Soluble factors from neuronal cultures induce a specific proliferation and resistance to apoptosis of cognate mouse skeletal muscle precursor cells

The mechanisms or the physiological events, which control the regeneration of skeletal muscle through muscle precursor cell multiplication and differentiation, are still largely unknown. To address the question of the involvement of neurons in this process, skeletal muscle progenitors were grown in the presence of conditioned media obtained from 3-day-old cultures of embryonic neurons (derived from either the dorsal or the ventral region of 11-day-old mouse embryos) or media conditioned with satellite cells. Strikingly, only satellite cells cultured in medium conditioned from ventral embryonic neurons exhibited increased proliferation, as well as resistance to staurosporine (STS)-induced apoptosis. Our results suggest the existence of specific anti-apoptogenic neural soluble signals, which could be involved in skeletal muscle regeneration pathways.     

Common virulence factors and genetic relationships between O18:K1:H7 Escherichia coli isolates of human and avian origin

Extraintestinal pathogenic (ExPEC) Escherichia coli strains of serotype O18:K1:H7 are mainly responsible for neonatal meningitis and sepsis in humans and belong to a limited number of closely related clones. The same serotype is also frequently isolated from the extraintestinal lesions of colibacillosis in poultry, but it is not well known to what extent human and avian strains of this particular serotype are related. Twenty-two ExPEC isolates of human origin and 33 isolates of avian origin were compared on the basis of their virulence determinants, lethality for chicks, pulsed-field gel electrophoresis (PFGE) patterns, and classification in the main phylogenetic groups. Both avian and human isolates were lethal for chicks and harbored similar virulence genotypes. A major virulence pattern, identified in 75% of the isolates, was characterized by the presence of F1 variant fimbriae; S fimbriae; IbeA; the aerobactin system; and genomic fragments A9, A12, D1, D7, D10, and D11 and by the absence of P fimbriae, F1C fimbriae, Afa adhesin, and CNF1. All but one of the avian and human isolates also belonged to major phylogenetic group B2. However, various subclonal populations could be distinguished by PFGE in relation to animal species and geographical origin. These results demonstrate that very closely related clones can be recovered from extraintestinal infections in humans and chickens and suggest that avian pathogenic E. coli isolates of serotype O18:K1:H7 are potential human pathogens.     

Changes in glycosylation of immunoglobulins in primary Sjögren's syndrome

Serum IgG and IgA are glycoprotein and significant glycoform abnormalities have been established in primary Sj?gren's syndrome. The proportion of asialylated IgG is abnormally high in the patients, whereas IgA1 and IgA2 appear to be over-sialylated. This peculiarity might explain the defective binding of IgA to asialoglycoreceptors. Furthermore, the activity of alpha 2,6 sialyl transferase is higher in the IgA-producing B cells from the patients than in the controls, whereas the alpha 2,3 sialyl transferase operates in the former cells but not in the latter. The mechanism of this enzyme dysregulation warrants elucidation.     

The binding of some human antiendothelial cell antibodies induces endothelial cell apoptosis.

The pathogenic role of antiendothelial cell antibodies (AECA) remains unclear. They are frequently associated with antibodies to anionic phospholipids (PL), such as phosphatidylserine (PS), which is difficult to reconcile with the distribution of PL molecular species within the plasma membrane. Since it is already known that PS is transferred to the outer face of the membrane as a preclude to apoptosis, the possibility exists that apoptosis is initiated by AECA. AECA-positive/anti-PL antibody-negative sera from eight patients with systemic sclerosis (SS) and 21 control patients were evaluated. Endothelial cells (EC) were incubated with AECA and the exposure of PS was established through the binding of annexin V. Hypoploid cell enumeration, DNA fragmentation, and optical and ultrastructural analyses of EC were used to confirm apoptosis. Incubation of EC with AECA derived from six of eight patients with SS led to the expression of PS on the surface of the cells. This phenomenon was significantly more frequent in SS (P < 0.04) than in control diseases. The redistribution of plasma membrane PS preceded other events associated with apoptosis: hypoploidy, DNA fragmentation, and morphology characteristic for apoptosis. Apoptosis-inducing AECA did not recognize the Fas receptor. We conclude that AECA may be pathogenic by inducing apoptosis.     

Increased N-linked glycosylation leading to oversialylation of monomeric immunoglobulin A1 from patients with Sjögren's syndrome

Increased serum immunoglobulin A (IgA) level is a common finding in primary Sjögren's syndrome (pSS). IgA might not be properly eliminated because of an abnormal glycosylation. We reported previously that IgA₁ from patients with pSS was oversialylated. We extend this finding by showing that monomeric IgA₁ contains more sialic acid (SA) in patients than in controls, as determined by enzyme‐linked immunosorbent assay (ELISA) and Western blot with Sambucus nigra agglutinin (SNA), a lectin specific for SA. To localize this excess of SA on the N‐ and/or O‐linked oligosaccharides, we analysed them separately, using N‐ and O‐linked oligosaccharide profiling kits based on fluorophore‐assisted carbohydrate electophoresis. N‐linked, but not O‐linked, oligosaccharides of patients' IgA₁ were oversialylated, and this seemed to be linked to an excess of SA on the same number of polysaccharides as normal IgA₁. To localize the abnormality to the Fab and/or Fc fragments, monomeric IgA₁ was digested with protease, separated and transferred to nitrocellulose, where SA was identified by SNA. Both Fab and Fc fragments appeared to be oversialylated. Oversialylation of N‐linked oligosaccharides of IgA₁ from patients with pSS might prevent the recognition of IgA by receptors that are responsible for their clearance, resulting in an excess of serum IgA and related immune complexes.