Conjugation of a new two-photon fluorophore to poly(ethylenimine) for gene delivery imaging

We report herein the molecular engineering of an efficient two-photon absorbing (TPA) chromophore based on a donor-donor bis-stilbenyl entity to allow conjugation with biologically relevant molecules. The dye has been functionalized using an isothiocyanate moiety to conjugate it with the amine functions of poly(ethylenimine) (PEI), which is a cationic polymer commonly used for nonviral gene delivery. Upon conjugation, the basic architecture and photophysical properties of the active TPA chromophore remain unchanged. At the usual N/P ratio (ratio of the PEI positive charges to the DNA negative charges) of 10 used for transfection, the transfection efficiency and cytotoxicity of the labeled PEI/DNA complexes were found to be comparable to those of the unlabeled PEI/DNA complexes. Moreover, when used in combination with unlabeled PEI (at a ratio of 1 labeled PEI to 3 unlabeled PEI), the labeled PEI does not affect the size of the complexes with DNA. The labeled PEI was successfully used in two-photon fluorescence correlation spectroscopy measurements, showing that at N/P = 10 most PEI molecules are free and the diffusion coefficient of the complexes is consistent with the 360 nm size measured by quasielastic light scattering. Finally, two-photon images of the labeled PEI/DNA complexes confirmed that the complexes enter into the cytoplasm of HeLa cells by endocytosis and hardly escape from the endosomes. As a consequence, the functionalized TPA chromophore appears to be an adequate tool to label the numerous polyamines used in nonviral gene delivery and characterize their complexes with DNA in two-photon applications.     

Docosahexaenoic acid is selectively enriched in plasma phospholipids during pregnancy in Trinidadian women--results of a pilot study

The fetal demand for docosahexaenoic acid (DHA) has to be satisfied by the mother. We determined the fatty acids in maternal plasma non-esterified fatty acid (NEFA), triacylglycerol (TAG) and phosphatidylcholine (PC), in a cross-sectional study of non-pregnant (n = 10), pregnant (n = 19), and postpartum (n = 9) women. There were lipid class-dependent differences in plasma polyunsaturated fatty acid (PUFA) concentrations between groups. During pregnancy, DHA was most highly enriched in PC, about 230%, with more modest enrichment for linoleic acid (LA) and arachidonic acid (AA), and no enrichment of alpha-linolenic acid (alpha-LNA). There was relative enrichment of LA, AA and alpha-LNA in TAG, but not of DHA. There was no specific enrichment of any PUFA in the NEFA pool. These data accord with the suggestion that the enrichment of alpha-LNA in TAG and of DHA in phospholipids reflects hepatic regulation of n-3 PUFA metabolism which potentially enhances the delivery of DHA to the placenta.     

Design,synthesis, and biological evaluation of a cephalosporin-monohydroguaiaretic acid prodrug activated by a monoclonal antibody-beta-lactamase conjugate

A novel cephalosporin derivative of monohydroguaiaretic acid (cephem-M(3)N, 7) was synthesized and found to possess anticancer activity against human leukemia (K562), breast carcinoma (MCF7), human lung cancer (A549), human colon cancer (Colo205) and pancreatic cancer cells (Capan2 and MiaPaCa2). A tumor targeting fusion protein (dsFv3-beta-lactamase) was also used in conjunction with cephem-based M(3)N 7 and its potency toward K562, MCF7, A549, Colo205, Capan2, and MiaPaCa2 was found to approach that of the free M(3)N (4). In the presence of dsFv3-beta-lactamase, tumor cells were found to be much more susceptible to conjugate 7 than normal human embryonic lung (HEL) cells and normal fibroblasts (Hef522). These notions provide a new approach to the use of nordihydroguaiaretic acid (NDGA) and its derivatives for antitumor therapy.     

Contribution of the putative heparan sulfate-binding motif BBXB of RANTES to transendothelial migration

The chemokines are a family of small chemoattractant proteins that have a range of functions, including activation and promotion of vectorial migration of leukocytes. Regulation on activation, normal T cell expressed and secreted (RANTES; CCL5), a member of the CC-chemokine subfamily, has been implicated in a variety of immune responses. In addition to the interaction of CC-chemokines with their cognate cell-surface receptors, it is known that they also bind to glycosaminoglycans (GAGs), including heparan sulfate. This potential for binding to GAG components of proteoglycans on the cell surface or within the extracellular matrix might allow formation of the stable chemokine concentration gradients necessary for leukocyte chemotaxis. In this study, we created a panel of mutant RANTES molecules containing neutral amino acid substitutions within putative, basic GAG-binding domains. Despite showing reduced binding to GAGs, it was found that each mutant containing a single amino acid substitution induced a similar leukocyte chemotactic response within a concentration gradient generated by free solute diffusion. However, we found that the mutant K45A had a significantly reduced potential to stimulate chemotaxis across a monolayer of microvascular endothelial cells. Significantly, this mutant bound to the CCR5 receptor and showed a potential to mobilize Ca(2+) with an affinity similar to the wild-type protein. These results show that the interaction between RANTES and GAGs is not necessary for specific receptor engagement, signal transduction, or leukocyte migration. However, this interaction is required for the induction of efficient chemotaxis through the extracellular matrix between confluent endothelial cells.     

Quasiperiodic Route to Chaos for the Dust Ion Acoustic Waves in Magnetized Dusty Plasmas

Plasma Physics Reports - Quasiperiodic and chaotic features of the dust ion acoustic (DIA) waves in a magnetized dusty plasma is studied. Reductive perturbation technique (RPT) is used to derive...     

Global patterns of geographic range size in birds

Large-scale patterns of spatial variation in species geographic range size are central to many fundamental questions in macroecology and conservation biology. However, the global nature of these patterns has remained contentious, since previous studies have been geographically restricted and/or based on small taxonomic groups. Here, using a database on the breeding distributions of birds, we report the first (to our knowledge) global maps of variation in species range sizes for an entire taxonomic class. We show that range area does not follow a simple latitudinal pattern. Instead, the smallest range areas are attained on islands, in mountainous areas, and largely in the southern hemisphere. In contrast, bird species richness peaks around the equator, and towards higher latitudes. Despite these profoundly different latitudinal patterns, spatially explicit models reveal a weak tendency for areas with high species richness to house species with significantly smaller median range area. Taken together, these results show that for birds many spatial patterns in range size described in geographically restricted analyses do not reflect global rules. It remains to be discovered whether global patterns in geographic range size are best interpreted in terms of geographical variation in species assemblage packing, or in the rates of speciation, extinction, and dispersal that ultimately underlie biodiversity.     

9,10-seco-9,19-Cyclolanostane arabinosides from the roots of Actaea podocarpa

Seven 9,10-seco-9,19-cyclolanostane arabinosides, named podocarpasides A-G (1-7), were isolated from the roots of Actaea podocarpa DC., a species closely related to black cohosh (a well known dietary supplement). Their structures were determined with the help of spectroscopic data including extensive 2D NMR spectroscopy. The isolates were found inactive, when tested for cytotoxic, estrogenic, and antioxidant activities in cell based assays. They were also tested for anticomplement activity against the classical pathway of complement system and only podocarpaside C (3) inhibited modest complement activity with an IC50 value of 200 microM.     

Inter-Segmental Coordination Pattern in Patients with Anterior Cruciate Ligament Deficiency during a Single-Step Descent

Anterior cruciate ligament injury is a debilitating pathology which may alter lower limb coordination pattern in both intact and affected lower extremities during activities of daily living. Emerging evidence supports the notion that kinematic variables may not be a good indicator to differentiate patients with anterior cruciate ligament deficiency during step descent task. The aim of the present study was to examine alterations in kinematics as well as coordination patterns and coordination variability of both limbs of these patients during a single step descent task. Continuous relative phase technique was used to measure coordination pattern and coordination variability between a group of anterior cruciate ligament deficient (n = 23) and a healthy control group (n = 23). A third order polynomial Curve fitting was utilized to provide a curve that best fitted to the data points of coordination pattern and coordination variability of the healthy control group. This was considered as a reference to compare to that of patient group using nonlinear regression analysis. The results of the present study demonstrated an altered coordination pattern of the supporting shank-thigh and the stepping foot-shank couplings in anterior cruciate ligament deficient subjects. It was further noticed that there was an increased coordination variability in foot-shank and shank-thigh couplings of both supporting and stepping legs. There was no significant difference in the hip, knee and ankle joints kinematics in either side of these patients. Anterior cruciate ligament deficient individuals showed altered strategies in both intact and affected legs, with increased coordination variability. Kinematic data did not indicate any significant difference between the two groups. It could be concluded that more sophisticated dynamic approach such as continuous relative phase would uncover discrepancies between the healthy and anterior cruciate ligament deficient individuals.