A major problem associated with therapy is the inability to deliver pharmaceuticals to a specific site of the body without causing nonspecific toxicity. Development of magnetic nanoparticles and techniques for their safe transport and concentration in specific sites in the body would constitute a powerful tool for gene/drug therapy in vivo. Furthermore, drug delivery in vitro could improve further if the drugs were modified with antibodies, proteins or ligands. For in vivo experiments, magnetic nanoparticles were conjugated with plasmid DNA expressing GFP and then coated with chitosan. These particles were injected into mice through tail vein and directed to heart and kidney by means of external magnets of 25 gauss or 2kA –kA/m. These particles were concentrated in the lungs, heart, and kidney of mice and the expression of GFP in these sites were monitored. The expression of GFP in specific locations was visualized by whole-body fluorescent imaging and the concentration of these particles in the designated body locations was confirmed by transmission electron microscopy. In another model system, we used atrial natriuretic peptide (ANP) and Carcino Embryonic Antigen (CEA) antibodies coupled to the chitosan coated magnetic nanoparticles to target cells in vitro. The present work demonstrates that a simple external magnetic field is all that is necessary to target a drug to a specific site inside the body without the need to functionalize the nanoparticles. However, the option to use magnetic targeting with external magnets on functionalized nanoparticles could prove as a more efficient means of drug delivery.

A cDNA clone (pPCM-1) for plant calmodulin was isolated by screening a potato stolon tip cDNA library with a chicken calmodulin cDNA. Nucleotide sequence analysis of pPCM-1 revealed that it contained 80 base pairs of 5' untranslated region, the entire coding region, and 376 base pairs of 3' untranslated region. Comparison of the nucleotide sequence of coding regions of potato and chicken calmodulin mRNA showed 78% homology. Comparison of the predicted amino acid sequence of potato calmodulin with other known calmodulin sequences indicated a high degree of homology with a few exceptions. Three changes in the amino acid sequence were found to be unique to the potato calmodulin sequence. In our earlier studies we showed the involvement of calcium and calmodulin in potato tuberization. The pPCM-1 clone was used as a probe to study the expression of calmodulin mRNA during tuberization and to monitor calmodulin mRNA level in various parts of the potato plant. Stolon tips showed the highest levels of calmodulin mRNA, suggesting a role for calmodulin in the tuberization process. In addition, pPCM-1 was used to investigate the effect of auxin and light on calmodulin gene expression in auxin-responsive strawberry fruit and light-responsive Merit corn roots, respectively. Both auxin and light signals were found to increase the level of mRNA for calmodulin. These results suggest that the altered calmodulin gene expression could be one of the molecular events involved in the signal transduction process in plants.Signals such as hormones, light, and gravity control diverse physiological processes in plants (1, 2). However, the biochemical and molecular events involved in the transduction of these signals are not clearly understood. Investigations from several laboratories suggest that calcium acts as a messenger in signal transduction (3-6). As Calmodulin gene structure and its expression have been well studied in animals (10-13). In animal cells, intracellular levels of calmodulin were shown to be unaffected by a number of steroid and peptide hormones (14). However, calmodulin levels were found to be elevated in transformed cells and also at the G1/S boundary of the growth cycle of mammalian cells (15)(16)(17)(18). In these cases, the changes in calmodulin were found to be accompanied or preceded by changes in the level of its mRNA (16,18 (vol/vol) ice-cold ethanol and kept overnight at -200C. The nucleic acid pellet was collected, dried, and dissolved in diethyl *The sequence reported in this paper is being deposited in the EMBL/GenBank data base (accession no. J04559). 3644The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.

Poly(lactide-co-glycolide) (PLGA), a biocompatible and biodegradable polyester co-polymer of PLA and PGA, has been recognized for its ability to deliver genes. However, gene delivery by PLGA nanoparticles is limited by their negative charge and their poor transport through mucosal barriers. In this study, PLGA nanoparticles were surface modified with cationic chitosan in an effort to improve their gene delivery capability. PLGA nanoparticles were synthesized by emulsion-diffusion-evaporation technique using PVA-chitosan (PLGA1) or PVA-chitosan-PEG (PLGA2) blend as stabilizers. This method is reproducible and produces nanoparticles with hydrodynamic diameter <200 nm. The nanoparticles were characterized by zetasizer, photon correlation spectroscopy and atomic force microscopy. A549 epithelial cells were transfected in vitro with PLGA particles complexed with a reporter plasmid encoding green fluorescent protein. PLGA particles transferred EGFP gene, but were less efficient than the lipofectamine control. The nanoparticles were also tested for their ability to transport across the nasal mucosa in vivo in mice. The results show that both PLGA1 and PLGA2 facilitate gene delivery and expression in vivo with increased efficiency and without causing inflammation, as measured by IL-6. Together, these results indicate that chitosan-modified PLGA nanoparticles have greater potential as gene carriers.

SummaryTo study the development of B lymphocyte memory, we identified and isolated splenic B cells expressing a highly defined antibody variable region that constitutes a reproducible and predominant component of the memory antibody response to p-azophenylarsonate (Ars). Isolation was achieved during the primary immune response by surface staining and flow cytometry using a specific anti-idiotypic antibody called E4, which recognizes this canonical V region, encoded by one set ofV gene segments. The isolated E4 + cells displayed all of the phenotypic characteristics of germinal center centrocytes, including a low level of surface Ig, a lack of surface IgD, a high level of receptor for peanut agglutinin, and expression of mutated antibody V genes.E4 § B cells were first detected in the spleen 7-8 d after primary immunization, reached peak numbers from days 10-13, and waned by day 16. Surprisingly, at their peak, E4 + cells comprised only 40,000 of all splenocytes, and half of these failed to bind Ars. Using this number, we estimate the total number of M-specific memory-lineage cells in the spleen to be no more than 50,000 (0.1%) at any one time, and presumably far fewer that are committed to the memory pool Chromosomal copies of rearranged V genes from single E4 + cells were amplified by nested PCR, and the amplified products were sequenced directly without cloning, using standardized conditions that disclose virtually no Taq polymerase errors. V gene sequence analyses of E4 + ceils isolated from single mice confirmed their canonical nature and revealed that they were derived from few precursors. In the average mouse, the E4 + pool was derived from fewer than five canonical precursors. Somatic mutations were found within the V genes of almost all cell isolates. At day 13, a significant fraction of E4 + cells had mutations known to increase antibody affinity for Ars, suggesting mey were products of at least one cycle of post-mutational antigen-driven selection. However, the lack of shared mutations by clonally related cells indicated that the selective expansion of mutant subclones typical of memory responses had not yet taken place. This was supported by the observation that half of the E4 + cells failed to bind Ars. Collectively, our results indicate that the memory compartment is a highly selected entity, even at relatively early stages of the primary immune response when somatic mutation and clonal selection are still in progress. If germinal centers are the source of memory B cells, our data suggest that B cell memory may be derived from only a small fraction of all germinal centers.T he development of memory B cells is strongly influenced by two antigen-dependent processes. One of these is a poorly defined somatic hypermutation mechanism that targets rearranged antibody variable region genes expressed by immune participants (1-12). The second is an intense selection process that recruits into the memory compartment rare B cell mutants expressing antibodies with improved affinity for antigen (reviewed in refe...

The use of chitosan nanoparticles as carriers for expression plasmids represents a major improvement in gene expression technology. We demonstrated previously that treatment with chitosan interferon-γ (IFN-γ) plasmid deoxyribonucleic acid (DNA) nanoparticles (chitosan interferon-γ nanogene [CIN]) led to in situ production of IFN-γ and a reduction in inflammation and airway reactivity in mice, but the mechanism underlying the immunomodulatory effects of CIN remains unclear. In this report, the effect of CIN treatment on the immune responses of CD8+ T cells and dendritic cells was examined in a BALB/c mouse model of ovalbumin (OVA)-induced allergic asthma. OT1 mice (OVA-T cell receptor [TCR] transgenic) were also used to test the effects of CIN on OVA-specific CD8+ T cells. CIN treatment caused a reduction in IFN-γ production in a subpopulation of OVA-specific CD8+ T cells cultured in vitro in the presence of OVA. CIN also reduced apoptosis of the CD8+ T cells. Examination of dendritic cells from lung and lymph nodes indicated that CIN treatment decreased their antigen-presenting activity, as evident from the reduction in CD80 and CD86 expression. Furthermore, CIN treatment significantly decreased the number of CD11c+b+ dendritic cells in lymph nodes, suggesting that endogenous IFN-γ expression may immunomodulate dendritic cell migration and activation. CIN therapy results in a reduction in proinflammatory CD8+ T cells and decreases the number and antigen-presenting activity of dendritic cells.

For rs5067, the risks of asthma in carriers of the C allele in the screening and replicate cohorts were reduced by 50% and 76%, respectively. NPPA may be an important susceptibility gene for asthma.

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