Neurotransmitter-Mediated Changes in the Electrophysiological Properties of Pituicytes

Intracellular recordings were obtained from pituicytes in the neural lobe of the isolated rat pituitary. Like other glia, pituicytes lacked action potentials in response to depolarizing current injection, but they tended to have more positive resting membrane potentials and higher input resistances than astrocytes in other preparations. Dye-coupling typical of astrocytes was also demonstrated amongst pituicytes, and their morphologies were similar to those of pituicytes stained for glial fibrillary acidic protein. Action potentials, anode-break spikes or barium spikes were not observed in pituicytes, even under conditions that maximized the elicitation of Ca²⁺-dependent responses. This suggests that pituicytes either have no or a very low density of Ca²⁺ channels or Ca²⁺ currents that are too small to generate action potentials. Dynorphin A (1–13), a kappa-opioid agonist, produced long-lasting increases in pituicyte input resistance with no significant changes in resting membrane potential. Dynorphin's action was concentration-dependent and was blocked by the opioid antagonist naloxone. This is consistent with previous reports demonstrating kappa-opioid receptors on pituicytes in the neurohypophysis. The β-adrenergic agonist isoproterenol (100 μM) reversed the increases in pituicyte input resistance produced by opioid application, with no significant changes in resting membrane potential. The fact that pituicytes responded to neurotransmitters suggests a functional link between pituicytes and neurosecretory nerve fibres.     

The course of a case of Maffucci's syndrome

The syndrome of Maffucci is characterized by angioma association of the enchondromatose. It is a relatively rare syndrome. The lesions are evolutived. The treatment is surgical. His pronostic is marqued by high percentage of malign degenerescence.     

Observations on two members of the Swedish family with congenital dyserythropoietic anaemia,type III

Abstract: Two affected individuals of the Swedish family with CDA, type III, in which the disease is transmitted as an autosomal dominant character, were studied. Both cases displayed features hitherto undescribed in this family but described in patients with CDA, type III, in whom the inheritance may have been as an autosomal recessive character. Such features were: (a) haemosiderinuria, (b) grossly disorganised erythroblast nuclei, (c) differences in the ultrastructural appearances of individual nuclei within the same multinucleate erythroblast and (d) intraerythroblastic inclusions resembling precipitated globin chains. In both cases the giant mononucleate erythroblasts and the multinucleate erythroblasts had total DNA contents up to 28c (1c = haploid DNA content) and 48c respectively, and some DNA synthesising bi- and multinucleate erythroblasts contained one or more nuclei which were unlabelled with ³H-thymidine. These findings are similar to those in patients with the autosomal recessive type of disease. Thus no major phenotypic differences are yet apparent between cases of CDA, type III, with different patterns of inheritance. Analysis of the surface erythrocyte proteins of the 2 Swedish CDA, type III, patients with monoclonal antibodies recognising Band 3, glycophorins A, B, C and D, Rh, CD44, CD47, CD55, CD58, CD59, Lutheran, Kell, LW and acetylcholinesterase did not reveal any gross abnormality of expression of these proteins. A slightly altered expression of blood group antigens A and H was revealed by the lectins Dolichos biflorus and Ulex europaeus and the Mr of Band 3 as judged by SDS polyacrylamide gel electrophoresis was also slightly reduced, suggesting that there may be minor alterations in the degree of N-glycosylation of some red cell membrane constituents.     

Cloning and sequencing of putative acetylcholinesterase cDNAs from the American dog tick, Dermacentor variabilis, and the brown dog tick, Rhipicephalus sanguineus (Acari: Ixodidae)

Two putative cDNAs of acetylcholinesterase (AChE), one from Dermacentor variabilis, and the other from Rhipicephalus sanguineus, were amplified and sequenced. The deduced amino acid sequences have high amino acid identities (between 70 and 94%) to known tick AChE sequences deposited in GenBank. Furthermore, these two AChEs also possess common features in their primary AChE structure such as catalytic active sites. A 2,220-bp contiguous sequence, containing a 1,791-bp open reading frame encoding an AChE precursor with 596 amino acid residues, was obtained from D. variabilis. The deduced proteins of R. sanguineus are different in size by 6 amino acids because of alternative splicing at the 5' end. A gene tree deduced from phylogenetic analysis indicates that there are at least three lineages of AChE in arthropods.     

Escherichia coli strains from pregnant women and neonates: intraspecies genetic distribution and prevalence of virulence factors

To determine the extent to which the vagina, endocervix, and amniotic fluid screen the Escherichia coli strains responsible for neonatal infections, we studied the genetic relationships among 105 E. coli strains isolated from all of the ecosystems involved in this infectious process. Twenty-four strains were isolated from the intestinal flora, and 25 strains were isolated from the vaginas of pregnant women. Twenty-seven strains were isolated from the amniotic fluid, blood, and cerebrospinal fluid (CSF) of infected neonates. The intraspecies genetic characteristics of all of the isolates were determined by random amplified polymorphic DNA (RAPD) analysis, PCR ECOR (E. coli reference) grouping, and PCR virulence genotyping. A correlation was found between the intraspecies distributions of the strains in the A, B1, B2, and D ECOR groups and in the two major RAPD groups (I and II). Nevertheless, the distribution of the E. coli strains in the RAPD groups according to their anatomical origins was more significant than their distribution in the ECOR groups. This may be explained by the existence of an E. coli subpopulation, defined by the RAPD I group, within the ECOR B2 group. This RAPD I group presents a major risk for neonates: 75% of the strains isolated from patients with meningitis and 100% of the strains isolated from patients with bacteremia were in this group. The vagina and the amniotic fluid are two barriers that favor colonization by highly infectious strains. Indeed, only 17% of fecal strains belonged to the RAPD I group, whereas 52% of vaginal strains and 67% of amniotic fluid strains belonged to this subpopulation. The ibeA and iucC genes were significantly associated with CSF strains, whereas the hly and sfa/foc genes were more frequent in blood strains. These findings could serve as a basis for developing tools to recognize vaginal strains, which present a high risk for neonates, for use in prophylaxis programs.     

Hydrophobic IgG-containing immune complexes in the plasma of autoimmune MRL/lpr mice, lactate dehydrogenase-elevating virus-infected mice, and pigs: association with transforming growth factor-beta and pH-dependent amplification

Persistent infection of mice with lactate dehydrogenase-elevating virus (LDV) is associated with polyclonal B cell activation, autoimmunity, and circulating hydrophobic IgG-containing immune complexes (ICs), which bind to the surfaces of uncoated ELISA plates in the presence of 0.05% Tween 20. We demonstrate here that hydrophobic IgG-containing ICs also appear naturally in the plasma of autoimmune MRL/lpr mice. These and the similar hydrophobic ICs of LDV-infected mice as well as pigs coincide on ELISA plate surfaces with TGF-beta, apparently in the form of an IgG-TGF-beta complex. Circulating hydrophobic IgG-containing ICs are also susceptible to considerable amplification in vitro by exposure to alkaline conditions. By this latter method, the fraction of in vivo hydrophobic IgG, relative to the maximum in vitro chemically inducible IgG, was found to be about 20% in the plasma of LDV-infected mice, 5% in normal mouse plasma, and less than about 2% in pig plasma. These results indicate the potential for both chemically induced and protein-binding contributions to the generation of hydrophobic IgG-containing molecules, and have implications for immunopathological mechanisms in autoimmunity and persistent virus infections.