Prominent Narp expression in projection pathways and terminal fields

Narp (neuronal activity regulated pentraxin) is a secreted immediate early gene product that is induced by synaptic activity. Recent studies have indicated that Narp may be an extracellular aggregating factor for AMPA receptors. Immunohistochemical studies have revealed prominent expression of Narp in the mossy fiber pathway of the dentate gyrus, suggesting it may be released pre-synaptically. However, in vitro studies using recombinant Narp indicate that Narp may act when expressed by either pre- or post-synaptic elements. To help define Narp's mode of action, we have examined its localization in the habenula-interpeduncular pathway which also displays robust Narp expression. Focusing on this pathway as well as hippocampal and cortical Narp expression, we found prominent Narp staining in projection pathways and terminal fields. In contrast, Narp expression in dendrites was minimal in these neuronal populations. These findings indicate that, under physiological conditions, Narp is targeted to the synapse from pre- rather than post-synaptic elements. Our results also suggest that future studies focusing on these projection pathways that express high levels of Narp, in vivo, may help to understand the regulation and function of endogenous Narp.     

Fine needle aspiration diagnosis in HIV-related lymphadenopathy in Mangalore, India

OBJECTIVE: To evaluate the usefulness of fine needle aspiration (FNA) study of lymph nodes in HIV-positive patients. STUDY DESIGN: The study was conducted at Kasturba Medical College, Mangalore, India. Samples from lymph nodes of 48 HIV-positive patients were taken and air dried, and wet smears were made. After staining with routine cytologic stains and special stains, detailed cytomorphologic study was conducted. RESULTS: Tuberculosis accounted for nearly half (48%) the cases,followed by HIV lymphadenitis (36%), lymphoma (10%), suppurative lymphadenitis (2%), Mycobacterium avium-intracellulare lymphadenitis (2%) and metastases (2%), in descending order of their frequency. A suppurative picture, which was found in 13% of cases of tuberculous lymphadenitis in AIDS patients, occasionally was misleading without the help of acid fast bacilli stain. CONCLUSION: FNA is a useful tool in the diagnosis of lymphadenopathy in HIV-positive patients provided that proper safety measures are taken to avoid contracting the infection.     

Nitration of profilin effects its interaction with poly (L-proline) and actin

Profilin from bovine spleen was nitrated with peroxynitrite; immunoblotting and spectrophotometric quantitation of nitrotyrosine residues suggested nitration of a single tyrosine residue in profilin with a stoichiometry of 0.6 mol of nitrotyrosine/mole of profilin. A decrease in the nitrotyrosine immunoreactivity of nitroprofilin during digestion with carboxypeptidase Y indicated that nitrotyrosine is located at the C-terminus of profilin. Nitroprofilin interaction with ligands such as phosphatidylinositol 4,5-bisphosphate, actin and poly (l-proline) was analyzed by monitoring the tryptophan fluorescence. Scatchard plot and binding isotherm data obtained revealed no significant difference in affinity of nitroprofilin to phosphatidylinositol 4,5-bisphosphate (K(d) of 4.8 +/- 0.5 muM for profilin, and K(d) of 5.7 +/- 0.6 muM for nitroprofilin), while poly (l-proline) binding studies revealed a twenty-fold increase in the affinity of profilin to poly (l-proline) upon nitration (K(d) of 21.8 +/- 1.7 muM for profilin, and K(d) of 1.1 +/- 0.1 muM for nitroprofilin). Actin polymerization studies involving pyrene-labeled actin indicated that profilin nitration inhibits the actin sequestering property of profilin. The critical actin monomer concentration (C(c)) was 150 and 250 nM in the presence of nitroprofilin and profilin, respectively. Thus, nitric oxide and free radicals produced under different conditions could alter the functions of profilin through nitration, such as its interaction with actin and poly (l-proline).     

Crystal structure of N-(benzyloxycarbonyl)aminoethyl-2,3,4,6-tetra-O-benzoyl-alpha-D-mannopyranoside: stabilization of the crystal lattice by a tandem network of N-H. . .O, C-H. . .O, and C-H. . .pi interactions

Single crystal X-ray analysis of an aminoethyl mannopyranoside, namely, N-(benzyloxycarbonyl)aminoethyl-2,3,4,6-tetra-O-benzoyl-alpha-D-mannopyranoside (1), shows that the compound crystallizes in the monoclinic space group P2(1), with two molecules in the unit cell. The mannopyranoside unit adopts a distorted 4C(1) conformation. An analysis of the intermolecular interactions reveals a tandem network of N-H. . .O, C-H. . .O, and C-H. . .pi interactions responsible for stabilizing the crystal lattice.     

Early localization of NPA58, a rat nuclear pore-associated protein, to the reforming nuclear envelope during mitosis

We have studied the mitotic reassembly of the nuclear envelope, using antibodies to nuclear marker proteins and NPA58 in F-111 rat fibroblast cells. In earlier studies we have proposed that NPA58, a 58 kDa rat nuclear protein, is involved in nuclear protein import. In this report, NPA58 is shown to be localized on the cytoplasmic face of the envelope in interphase cells, in close association with nuclear pores. In mitotic cells NPA58 is dispersed in the cytoplasm till anaphase. The targeting of NPA58 to the reforming nuclear envelope in early telophase coincides with the recruitment of a well-characterized class of nuclear pore proteins recognized by the antibody mAb 414, and occurs prior to the incorporation of lamin B1 into the envelope. Significant protein import activity is detectable only after localization of NPA58 in the newly-formed envelope. The early targeting of NPA58 is consistent with its proposed role in nuclear transport.     

Actin polymerization in response to different chemoattractants is reduced in granulocytes from chronic myeloid leukemia patients

Chronic myeloid leukemia (CML), a hematopoietic stem cell disorder, is characterized by the presence of Philadelphia chromosome (Ph1). Earlier studies have shown that various functions, such as chemotaxis, fluid phase pinocytosis, phagocytosis, and degranulation in response to chemotactic peptide formyl-methionyl-leucyl-phenylalanine (fMLP), were defective in polymorphonuclear leukocytes (PMNL) from CML patients. These functions depend on actin microfilaments (MF). Further studies showed that fMLP-induced actin polymerization was lower in CML PMNL. To see if this defect is specific to stimulation by fMLP alone or is a global phenomenon involving other chemoattractant receptors, chemotaxis and actin polymerization were studied in response to fMLP, an analog of fMLP, formyl-methionine-1 aminocyclooctane 1 carboxylic acid-phenyalanine-O-methionine (FACC8), platelet-activating factor (PAF), and leukotriene B4 (LTB4). These compounds bind to different chemoattractant receptors. Chemotaxis and actin polymerization in response to all four chemoattractants were significantly lower in CML PMNL compared with PMNL from normal subjects and were differentially affected for the different chemoattractants. These results suggest a global phenomenon involving all four chemoattractant-stimulated pathways. This lower amount of F-actin may be responsible for the defective chemotaxis seen in these cells.     

Doing the unexpected: proteins involved in hydrogen peroxide perception

A look back at the early literature on reactive oxygen species (ROS) gives the impression that these small inorganic molecules had a singular defined role, that of host defence in mammalian systems. However, it is now known that their roles also include a major part in cell signalling, in a broad range of organisms from mammals to plants. Similarly, a look back at papers on the proteins now thought to be involved in the perception of hydrogen peroxide (H(2)O(2)) will show that they too had defined functions assigned to them, completely independent to H(2)O(2) signalling. These proteins have disparate roles, in ethylene perception or even major metabolic pathways such as glycolysis. However, the chemistry of H(2)O(2) sensing dictates that the proteins have a commonality, with active thiol groups being potential ROS targets. The challenge now is to determine the full range of proteins which may partake in the role of H(2)O(2) perception, and to determine the mechanisms by which the signal is transmitted to the next players in the signal transduction pathways.     

Preface to Nitric Oxide Signalling: Plant Growth and Development

Interest in nitric oxide (NO) as an endogenous and potent regulatorof plant growth and development has grown exponentially in thelast few years. The Focus Section in this issue of Journal ofExperimental Botany (JXB) contains six papers based on invitedtalks from a session held at the Society for Experimental Biology(SEB) Annual Meeting in Barcelona, Spain, in