Stemmed DNA nanostructure for the selective delivery of therapeutics.

DNA has emerged as a biocompatible biomaterial that may be considered for various applications. Here, we report tumor cell-specific aptamer-modified DNA nanostructures for the specific recognition and delivery of therapeutic chemicals to cancer cells. Protein tyrosine kinase (PTK)7-specific DNA aptamer sequences were linked to 15 consecutive guanines. The resulting aptamer-modified product, AptG15, self-assembled into a Y-shaped structure. The presence of a G-quadruplex at AptG15 was confirmed by circular dichroism and Raman spectroscopy. The utility of AptG15 as a nanocarrier of therapeutics was tested by loading the photosensitizer, methylene blue (MB), to the G-quadruplex as a model drug. The generated MB-loaded AptG15 (MB/AptG15) showed specific and enhanced uptake to CCRF-CEM cells, which overexpress PTK7, compared with Ramos cells, which lack PTK7, or CCRF-CEM cells treated with a PTK7-specific siRNA. The therapeutic activity of MB/AptG15 was tested by triggering its photodynamic effects. Upon 660 nm light irradiation, MB/AptG15 showed greater reactive oxygen species generation and anticancer activity in PTK7-overexpressing cells compared to cells treated with MB alone, those treated with AptG15, and other comparison groups. AptG15 stemmed DNA nanostructures have significant potential for the cell-type-specific delivery of therapeutics, and possibly for the molecular imaging of target cells.

Immune-camouflaged graphene oxide nanosheets for negative regulation of phagocytosis by macrophages.

Signal regulatory protein alpha (SIRPα) is highly expressed in macrophages of the reticuloendothelial system and in tumor-associated macrophages, whereas tumor cells express the surface membrane protein, CD47, which interacts with SIRPα to negatively regulate phagocytosis. In this study, we modified the surfaces of graphene oxide (GO) nanosheets with a CD47-like SIRPα-binding peptide (SP). The presence of SP on GO nanosheets reduced the macrophage uptake to a greater extent than the PEGylation of such nanosheets. This reduced uptake was found to be mediated by the activation of Src homology region 2 domain-containing phosphatase 1 (SHP-1) and the downstream inhibition of myosin assembly, which is necessary for phagosome formation. Unlike SP-coated GO nanosheets, PEGylated GO nanosheets did not affect myosin assembly or phagocytosis. After in vivo systemic administration, the clearance of SP-coated GO nanosheets was slower than that of PEGylated GO nanosheets, and this difference increased with repeated administration. Finally, SP-coated GO nanosheets showed a higher distribution to tumor tissues than PEGylated GO nanosheets or a physical mixture of SP and GO nanosheets. Our findings indicate that immune-camouflaged GO nanosheets with natural CD47-like SIRPα-binding molecules can reduce the nonspecific loss of such nanosheets through macrophage uptake, thereby enhancing their blood circulation and tumor delivery after multiple injections.

Expression of autotaxin and lysophosphatidic acid receptors 1 and 3 in the developing rat lung and in response to hyperoxia.

We sought to evaluate lysophosphatidic acid (LPA) signaling improvement in lung development by assessing the expression of autotaxin and LPA receptor 1 and 3 (LPAR1 and LPAR3) in the neonatal rat lung during normal perinatal development and in response to hyperoxia. In the developmental study, rats were sacrificed on days 17, 19, and 21 of gestation; on postnatal days 1, 4, and 7; and at adulthood (postnatal 9 weeks). In the hyperoxia study, 42 postnatal 4-day-old rat pups were divided into seven groups and exposed to either 85% O2 for 24, 72, or 120 h or room air for 0, 24, 72, or 120 h. The rats were then euthanized after 0, 24, 72, and 120 h of exposure. Immunofluorescence demonstrated that autotaxin, LPAR1, and LPAR3 proteins were broadly colocalized in airway epithelial cells, but mainly distributed in vascular endothelial and mesenchymal cells during the first postnatal week. The expression of autotaxin, LPAR1, and LPAR3 were increased during late gestation and then decreased after birth. Autotaxin expression and enzymatic activity were significantly increased at 72 and 120 h after exposure to hyperoxia. LPAR1 and LPAR3 expression was also increased after 120 h of hyperoxic exposure. These findings suggest that LPA-associated molecules were upregulated at birth and induced by hyperoxia in the developing rat lung. Therefore, the LPA pathway may be involved in normal lung development, including vascular development, as well as wound-healing processes of injured neonatal lung tissue, which is at risk of neonatal hyperoxic acute lung injury.

Telomere shortening: a new prognostic factor for cardiovascular disease post-radiation exposure.

Telomere length has been proposed as a marker of mitotic cell age and as a general index of human organism aging. Telomere shortening in peripheral blood lymphocytes has been linked to cardiovascular-related morbidity and mortality. The authors investigated the potential correlation of conventional risk factors, radiation dose and telomere shortening with the development of coronary artery disease (CAD) following radiation therapy in a large cohort of Hodgkin lymphoma (HL) patients. Multivariate analysis demonstrated that hypertension and telomere length were the only independent risk factors. This is the first study in a large cohort of patients that demonstrates significant telomere shortening in patients treated by radiation therapy who developed cardiovascular disease. Telomere length appears to be an independent prognostic factor that could help determine patients at high risk of developing CAD after exposure in order to implement early detection and prevention.

Complete condensation in a zero range process on scale-free networks.

We study a zero range process on scale-free networks in order to investigate how network structure influences particle dynamics. The zero range process is defined with the rate p(n) = n(delta) at which particles hop out of nodes with n particles. We show analytically that a complete condensation occurs when delta < or = delta(c) triple bond 1/(gamma-1) where gamma is the degree distribution exponent of the underlying networks. In the complete condensation, those nodes whose degree is higher than a threshold are occupied by macroscopic numbers of particles, while the other nodes are occupied by negligible numbers of particles. We also show numerically that the relaxation time follows a power-law scaling tau approximately L(z) with the network size L and a dynamic exponent z in the condensed phase.

Analytic study of the three-urn model for separation of sand.

We present an analytic study of the three-urn model for separation of sand, which can be regarded as a zero-range process. We solve analytically the master equation and the first-passage problem. We find that the stationary probability distribution obeys the detailed balance and is governed by the free energy. We find that the characteristic lifetime of a cluster diverges algebraically with exponent 1/3 at the limit of stability. We also give a general argument that the scaling behavior is robust with respect to different expressions of the flux.

Optimal capacity of the Blume-Emery-Griffiths perceptron.

A Blume-Emery-Griffiths perceptron model is introduced and its optimal capacity is calculated within the replica-symmetric Gardner approach, as a function of the pattern activity and the embedding stability parameter. The stability of the replica-symmetric approximation is studied via the analog of the de Almeida-Thouless line. A comparison is made with other three-state perceptrons.

Analytic study of the urn model for separation of sand.

We present an analytic study of the urn model for separation of sand recently introduced by Lipowski and Droz [Phys. Rev. E 65, 031307 (2002)]. We solve analytically the master equation and the first-passage problem. The analytic results confirm the numerical results obtained by Lipowski and Droz. We find that the stationary probability distribution and the shortest one among the characteristic times are governed by the same free energy. We also analytically derive the form of the critical probability distribution on the critical line, which supports their results obtained by numerically calculating Binder cumulants (A. Lipowski and M. Droz, e-print cond-mat/0201472).

Gap structure of the local field in symmetric Q Ising neural networks.

The time evolution of the local field in symmetric Q-Ising neural networks is studied for arbitrary Q. In particular, the structure of the noise and the appearance of gaps in the probability distribution are discussed. Results are presented for several values of Q and compared with numerical simulations.

Ellagic acid rhamnosides from the stem bark of Eucalyptus globulus.

Four ellagic acid rhamnosides were isolated from the stem bark of Eucalyptus globulus. Their structures have been established on the basis of the analysis of their 1H NMR, 13C NMR, HMBC, IR and MS spectral data. The HMBC data of these compounds were most useful for their structure determinations, with these bring determined to be 3-O-methylellagic acid 3'-O-alpha-rhamnopyranoside, 3-O-methylellagic acid 3'-O-alpha-3''-O-acetylrhamnopyranoside, 3-O-methylellagic acid 3'-O-alpha-2''-O-acetylrhamnopyranoside, 3-O-methylellagic acid 3'-O-alpha-4''-O-acetylrhamnopyranoside, respectively. Their antioxidant activities were evaluated by measuring the inhibition of lipid peroxidation using rat liver microsomes, with IC50 values of 10.0-14.0 microg/ml.

Regulation of gene expression, cellular localization, and in vivo function of Caenorhabditis elegans DNA topoisomerase I.

BACKGROUND: DNA topoisomerase I is dispensable in yeast, but is essential during the embryogenesis of Drosophila and mouse. In order to determine functions of the enzyme in the development of Caenorhabditis elegans, phenotypes resulting from the deficiency were observed and correlated with the expression of the gene. RESULTS: The transcriptional regulation of the C. elegans DNA topoisomerase I gene was investigated by mRNA localization and reporter gene expression in C. elegans. The mRNA was expressed in the gonad and in the early embryos, followed by a rapid decrease in its level during the late embryonic stage. A reporter gene expression induced by the 5'-upstream DNA sequence appeared at the comma stage of embryos, continued through the L1 larval stage, and began to decrease gradually afterwards. The DNA topoisomerase I protein was immuno-localized in the nuclei of meiotic gonad cells and interphase embryonic cells, and unexpectedly in centrosomes of mitotic embryonic cells. Double-stranded RNA interference of DNA topoisomerase I gene expression resulted in pleiotropic phenotypes showing abnormal gonadogenesis, oocyte development and embryogenesis. CONCLUSION: These phenotypes, along with expressional regulations, demonstrate that DNA topoisomerase I plays important roles in rapidly growing germ cells and embryonic cells.

Lipid peroxidation inhibitory activity of some constituents isolated from the stem bark of Eucalyptus globulus.

Twelve compounds with lipid peroxidation inhibitory activity were isolated from the stem bark of E. globulus. Their structures were assigned as a new aromatic monoterpene (1) and eleven known compounds, pinoresinol (2), vomifoliol (3), 3,4,5-trimethoxyphenol 1-O-beta-D-(6'-O-galloyl)glucopyranoside (4), methyl gallate (5), rhamnazin (6), rhamnetin (7), eriodictyol (8), quercetin (9), taxifolin (10), engelitin (11), and catechin (12) on the basis of UV, mass, and NMR spectroscopic analyses. These compounds except vomifoliol significantly inhibited lipid peroxidation in rat liver microsome.

Pituitary adenylate cyclase activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP) stimulate interleukin-6 production through the third subtype of PACAP/VIP receptor in rat bone marrow-derived stromal cells.

Regulation of Interleukin-6 (IL-6) production in bone marrow (BM)-derived stromal cells by neuropeptides, pituitary adenylate cyclase activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP), was examined. Both forms of PACAP, PACAP-27 and PACAP-38, as well as VIP significantly increased IL-6 production by rat BM-derived stromal cells at physiological concentrations ranging from 10(-10)-10(-8) M. The three related peptides (PACAP-27, -38, and VIP) stimulated the production of both cAMP and inositol 1,4,5-trisphosphate (IP3) in rat BM-derived stromal cells with similar 50% effective concentrations. The stimulatory potency of the three related peptides for the production of IL-6, cAMP, and IP3 was almost consistent, suggesting that the dual signaling transduction pathways may be involved in PACAP/VIP-induced IL-6 production in rat BM-derived stromal cells. The messenger RNA (mRNA) for the third subtype of PACAP receptor (PVR3) was found to be abundantly expressed in both BM-derived stromal cells and the BM tissue, whereas little of the mRNA for type 1 (PVR1) nor type 2 (PVR2) was detected. Furthermore, the mRNAs for PACAP and VIP were detected in the BM tissue, suggesting that both PACAP/VIP and PVR3 are synthesized in vivo in the BM. The results shown in this paper suggest that PACAP/VIP and their receptor play an important role in the IL-6 production and perhaps in the hematopoiesis in the BM.

Optimal nonlinear training in the multi-class proximity problem.

Using a signal-to-noise analysis, the effects of nonlinear modulation of the Hebbian learning rule in the multi-class proximity problem are investigated. Both random classification and classification provided by a Gaussian and a binary teacher are treated. Analytic expressions are derived for the learning and generalization rates around an old and a new prototype. For the proximity problem with binary inputs but Q'-state outputs, it is shown that the optimal modulation is a combination of a hyperbolic tangent and a linear function. As an illustration, numerical results are presented for the two-class and the Q' = 3 multi-class problem.

Opposite actions of transforming growth factor-beta 1 on the gene expression of atrial natriuretic peptide biological and clearance receptors in a murine thymic stromal cell line.

The regulation of the gene expression of the atrial natriuretic peptide receptor (ANPR) subtypes, ANPR-A, ANPR-B, and ANPR-C, was investigated in a murine thymic stromal cell line, MRL 104.8a. When MRL 104.8a cells were cultured with transforming growth factor (TGF)-beta1, [125I]ANP binding sites increased with increasing dose of TGF-beta1. These binding sites were identified as ANPR-C by a displacement experiment with ANPR-C-specific ligand, C-ANF, and by the affinity cross-linking of the [125I]ANP binding sites with a chemical cross-linker to determine the molecular weight of the ANPR. This augmentation of the ANPR-C expression was elucidated to occur at the transcriptional level by Northern blot experiment, comparison of the relative amounts of mRNA by reverse transcription (RT)-PCR, and in vitro nuclear transcription assay. Conversely, the expression of the ANP biological receptors, ANPR-A and ANPR-B, was shown to be down-regulated by TGF-beta1. These data suggest that TGF-beta1 regulates the gene expression of ANPRs in the thymic stromal cells and that ANP and TGF-beta1 might affect the thymic stromal cell functions.

First metatarsophalangeal joint arthrodesis with the Truncated Cone Reamer System.

This manuscript introduces to the podiatric community the Truncated Cone Reamer (TCR) System for precise fashioning of the first metatarsal and proximal phalanx for a first metatarsophalangeal joint peg-in-hole type arthrodesis. As the name of the system suggests, the device reams out a truncated male cone at the metatarsal head and a corresponding female cone at the phalangeal base in the desired position. There is congruous cancellous bony contact at all apposing surfaces of the truncated cone for bony consolidation. The peg-in-hole intrinsically confers the arthrodesis stability. The authors present a step-by-step use of the TCR system, and a 1 year follow-up case study in which the TCR system was used as a template.