No variation in the prevalence of point mutations in the <Emphasis Type="Italic">Pfcrt</Emphasis> and <Emphasis Type="Italic">Pfmdr1</Emphasis> genes in isolates from Gabonese patients with uncomplicated or severe <Emphasis Type="Italic">Plasmodium falciparum</Emphasis> malaria

In Lambaréné (Gabon), where a high level of Plasmodium falciparum resistance to chloroquine has been reported, we assessed the relationship between polymorphisms in the P. falciparum chloroquine resistance transporter (Pfcrt) and multidrug resistance-1 (Pfmdr1) genes and the clinical severity of malaria. Ninety-one and 60 P. falciparum isolates from children with uncomplicated or severe malaria were collected in 1996 and 2002, respectively. Single nucleotide mutations at codon 76 in the Pfcrt gene and at codons 86, 184, 1034, 1042, and 1246 in the Pfmdr1 gene were assessed by PCR-RFLP. All P. falciparum isolates presented the Pfcrt K76T mutation, whatever the clinical status. A high prevalence (>80%) of the Pfmdr1 86Tyr and 184Phe mutations was detected at both time points and in both clinical groups. We did not identify any specific mutation in the Pfmdr1 gene associated with the severity of disease, and the multiplicity of P. falciparum infection was also similar in both groups. Our results showed no change in the polymorphism of Pfcrt and Pfmdr1 genes in P. falciparum isolates collected in 1996 and 2002, and the severity of the disease was not associated with specific mutations neither in the Pfcrt nor in the Pfmdr1 genes in the study site.     

Cell imaging beyond the diffraction limit using sparse deconvolution spatial light interference microscopy

We present an imaging method, dSLIM, that combines a novel deconvolution algorithm with spatial light interference microscopy (SLIM), to achieve 2.3x resolution enhancement with respect to the diffraction limit. By exploiting the sparsity of the phase images, which is prominent in many biological imaging applications, and modeling of the image formation via complex fields, the very fine structures can be recovered which were blurred by the optics. With experiments on SLIM images, we demonstrate that significant improvements in spatial resolution can be obtained by the proposed approach. Moreover, the resolution improvement leads to higher accuracy in monitoring dynamic activity over time. Experiments with primary brain cells, i.e. neurons and glial cells, reveal new subdiffraction structures and motions. This new information can be used for studying vesicle transport in neurons, which may shed light on dynamic cell functioning. Finally, the method is flexible to incorporate a wide range of image models for different applications and can be utilized for all imaging modalities acquiring complex field images.     

Induction of anti-tumor cytotoxic T cell responses through PLGA-nanoparticle mediated antigen delivery

Nanotechnology-based antigen delivery has been developing as a vaccine strategy due to its dose-sparing and prolonged antigen presentation features. In the current study, we examined the feasibility of nanoparticle (NP)-mediated delivery of antigenic peptides to efficiently induce cytotoxic T lymphocyte responses against tumor-associated self-antigens in C57BL/6 mouse models. The biodegradable poly(D,L-lactide-co-glycolide) nanoparticle (PLGA-NP) carrying murine melanoma antigenic peptides, hgp100(25-33) and TRP2(180-188), were prepared by double emulsion method. Efficient uptake of PLGA-NP by murine dendritic cells was shown in vitro and in vivo, using NP labeled with the fluorescent dye DiD. Intradermal injection of peptide-loaded PLGA-NP into mice induced antigen-specific T cell responses more strongly than the peptides mixed with Freund's adjuvant. More importantly, vaccination with PLGA-NP carrying both TRP2(180-188) and a toll-like receptor 4 agonist, monophosphoryl lipid A, significantly delayed growth of subcutaneously inoculated B16 melanoma cells in a prophylactic setting. Furthermore, the anti-tumor activity of NP-mediated peptide vaccination was significantly augmented by combined treatment with interferon-γ, which might prevent tumor escape through up-regulation of MHC class I expression on tumor cells. Our findings demonstrate the feasibility of NP-mediated antigen delivery for cancer immunotherapy, in particular when immune escape mechanisms of tumor cells are blocked simultaneously.     

Effects of acute and chronic exposure to both 900 MHz and 2100 MHz electromagnetic radiation on glutamate receptor signaling pathway

Purpose: To demonstrate the molecular effects of acute and chronic exposure to both 900 and 2100?MHz radiofrequency electromagnetic radiation (RF-EMR) on the hippocampal level/activity of some of the enzymes – including PKA, CaMKIIα, CREB, and p44/42 MAPK – from N-methyl-D-aspartate receptor (NMDAR)-related signaling pathways.

Materials and methods: Rats were divided into the following groups: sham rats, and rats exposed to 900 and 2100?MHz RF-EMR for 2?h/day for acute (1 week) or chronic (10 weeks), respectively. Western blotting and activity measurement assays were used to assess the level/activity of the selected enzymes.

Results: The obtained results revealed that the hippocampal level/activity of selected enzymes was significantly higher in the chronic groups as compared to the acute groups at both 900 and 2100?MHz RF-EMR exposure. In addition, hippocampal level/activity of selected enzymes was significantly higher at 2100?MHz RF-EMR than 900?MHz RF-EMR in both acute and chronic groups.

Conclusions: The present study provides experimental evidence that both exposure duration (1 week versus 10 weeks) and different carrier frequencies (900 vs. 2100?MHz) had different effects on the protein expression of hippocampus in Wistar rats, which might encourage further research on protection against RF-EMR exposure.