This paper examines a particular aspect of glial-neuronal interactions during central nervous system development: the possible influence of growing neurites on the expression of glial-associated extracellular matrix (ECM) molecules. In particular, using in vivo manipulations of the dopaminergic projections from the midbrain substantia nigra, as well as an in vitro model of the developing nigrostriatal circuit, we look at the reciprocal interactions between growing dopaminergic axons and astrocyte-derived ECM molecules in the striatum. Glial-derived glycoconjugates, including tenascin and a proteoglycan designated DSD-1, are developmentally expressed ECM molecules which have been shown to have different effects on immature neurons and their growing processes. Here we show that the glial expression of these ECM constituents in a target region (the caudate-putamen or neostriatum) may be affected by the presence or absence of an appropriate, maturing afferent projection (in this case, dopaminergic nigrostriatal axons). In general, our results reveal complex glial-neuronal interactions during the normal development of central nervous system circuits, and the ability to create in vivo and in vitro models which may be useful toward understanding these complex cellular and molecular interactions in degeneration and plasticity of the nigrostriatal circuit in diseases including Parkinson's.

Animals↗

PubMedDate not supplied

Laboratory surveillance of synergy between and resistance to trimethoprim and sulfonamides.

Results of susceptibility tests of Enterobacteriaceae isolated at 14 different centers demonstrate synergy between trimethoprim (TMP) and sulfamethoxazole (SMZ) against sulfonamide-susceptible isolates, which account for between less than 50% and greater than 75% of the isolates at different centers. Only 1%-4% of the isolates of Escherichia coli or Proteus mirabilis from the five centers in the United States were found to be resistant when tested with a disk containing both TMP and SMZ, but greater than 8% of such isolates from five of the other centers were resistant to the combination disk. A larger percentage of isolates of Klebsiella pneumoniae or Serratia marcescens were resistant, but the number varied from center to center. In the United States, resistance of human and animal isolates of Salmonella to the TMP-SMZ combination was almost completely absent, although greater than 50% of the animal isolates were resistant to sulfonamides. At a center that tested TMP and SMZ resistance with separate disks, resistance to TMP was found to be 30 times more common in sulfonamide-resistant than in sulfonamide-susceptible E. coli. This ratio may be useful as a monitor as treatment with TMP alone increases.

Bacteria↗

PubMedDate not supplied

Resistance of bacteria to antibacterial agents: report of Task Force 2.

The use of a growing number of antibacterial agents over the past half century has elicited a widespread deployment of genes for resistance to these agents in populations of bacteria throughout the world. Task Force 2 of the NIH Study on Antibiotic Use and Antibiotic Resistance Worldwide found that data on prevalence of resistance was fragmentary and underanalyzed but indicative of several trends. Resistance to older antibacterial agents appears to have stabilized overall, but shifts of resistance genes into new strains and species have continued to cause new clinical problems. Resistance to newer antibacterial agents has increased. Resistance is more prevalent in developing countries. Systematic surveillance of resistance integrated with understanding of its molecular basis is needed for control of resistance.

Aminoglycosides↗

PubMedDate not supplied

WHONET: an information system for monitoring antimicrobial resistance.

Explore the source record for details and available documents.

Anti-Bacterial Agents↗

PubMedDate not supplied

Endodermal sinus tumor of the mediastinum. Cytologic diagnosis on a pleural effusion.

A primary mediastinal endodermal sinus tumor in a young man was diagnosed by cytologic examination of a pleural effusion. Subsequent evaluation revealed a greatly elevated serum alphafetoprotein (AFP); computed tomographic scan of the chest showed a large anterior mediastinal mass. Routine examination of the smears and cell block preparations revealed clusters of tumor cells with a few intracytoplasmic hyaline droplets. Immunohistochemical stains for AFP, alpha-1-antitrypsin and cytokeratin were positive in the tumor cells while stains for carcinoembryonic antigen and the beta subunit of human chorionic gonadotropin were negative. This supported the diagnosis of endodermal sinus tumor, a rare primary tumor within the mediastinum.

Adult↗