Development of an Improved Rapidly Exploring Random Trees Algorithm for Static Obstacle Avoidance in Autonomous Vehicles.

Safe path planning for obstacle avoidance in autonomous vehicles has been developed. Based on the Rapidly Exploring Random Trees (RRT) algorithm, an improved algorithm integrating path pruning, smoothing, and optimization with geometric collision detection is shown to improve planning efficiency. Path pruning, a prerequisite to path smoothing, is performed to remove the redundant points generated by the random trees for a new path, without colliding with the obstacles. Path smoothing is performed to modify the path so that it becomes continuously differentiable with curvature implementable by the vehicle. Optimization is performed to select a "near"-optimal path of the shortest distance among the feasible paths for motion efficiency. In the experimental verification, both a pure pursuit steering controller and a proportional-integral speed controller are applied to keep an autonomous vehicle tracking the planned path predicted by the improved RRT algorithm. It is shown that the vehicle can successfully track the path efficiently and reach the destination safely, with an average tracking control deviation of 5.2% of the vehicle width. The path planning is also applied to lane changes, and the average deviation from the lane during and after lane changes remains within 8.3% of the vehicle width.

Synthesis and Self-Assembly of a Mikto-Arm Star Dual Drug Amphiphile Containing both Paclitaxel and Camptothecin.

Self-assembly of anticancer therapeutics into discrete nanostructures provides an innovative way to develop a self-delivering nanomedicine with a high, quantitative drug loading. We report here the synthesis and assembly of a mikto-arm star dual drug amphiphile (DA) containing both a bulky paclitaxel (PTX) and a planar camptothecin (CPT). The two anti-cancer drugs of interest were stochastically conjugated to a ß-sheet forming peptide (Sup35) and under physiologically-relevant conditions the dual DA could spontaneously associate into supramolecular filaments with a fixed 41% total drug loading (29% PTX and 12% CPT). Transmission electron microscopy imaging and circular dichroism spectroscopy studies reveal that the bulkiness of the PTX, as well as the π-π interaction preference between the CPT units, has a significant impact on the assembly kinetics, molecular level packing, and nanostructure morphology and stability. We found that the DA containing two PTX units assembled into non-filamentous micelle-like structures, in contrast to the filamentous structures formed by the hetero dual DA and the DA containing two CPTs. The hetero dual DA was found to effectively release the two anticancer agents, exhibiting superior cytotoxicity against PTX-resistant cervical cancer cells. The presented work offers a potential method to generate well-defined entwined filamentous nanostructures and provides the basis for a future combination therapy platform.

Kinetic quantification of protein polymer nanoparticles using non-invasive imaging.

Protein polymers are repetitive amino acid sequences that can assemble monodisperse nanoparticles with potential applications as cancer nanomedicines. Of the currently available molecular imaging methods, positron emission tomography (PET) is the most sensitive and quantitative; therefore, this work explores microPET imaging to track protein polymer nanoparticles over several days. To achieve reliable imaging, the polypeptides were modified by site-specific conjugation using a heterobifunctional sarcophagine chelator, AmBaSar, which was subsequently complexed with (64)Cu. AmBaSar/(64)Cu was selected because it can label particles in vivo over periods of days, which is consistent with the timescales required to follow long-circulating nanotherapeutics. Using an orthotopic model of breast cancer, we observed four elastin-like polypeptides (ELPs)-based protein polymers of varying molecular weight, amino acid sequence, and nanostructure. To analyze this data, we developed a six-compartment image-driven pharmacokinetic model capable of describing their distribution within individual subjects. Surprisingly, the assembly of an ELP block copolymer (78 kD) into nanoparticles (R(h) = 37.5 nm) minimally influences pharmacokinetics or tumor accumulation compared to a free ELP of similar length (74 kD). Instead, ELP molecular weight is the most important factor controlling the fate of these polymers, whereby long ELPs (74 kD) have a heart activity half-life of 8.7 hours and short ELPs (37 kD) have a half-life of 2.1 hours. These results suggest that ELP-based protein polymers may be a viable platform for the development of multifunctional therapeutic nanoparticles that can be imaged using clinical PET scanners.

Effect of preserving condition of porcine ovaries on the development of in vitro matured oocytes.

The effect of preservation condition of ovaries on the in vitro maturation of the porcine oocytes was studied. Cumulus-oocyte complexes (COCs) were obtained from the ovaries preserved in Dulbecco's phosphate buffered saline (PBS) solution at various temperatures for different time intervals, and cultured in M199 maturation medium. Matured oocytes were obtained from the ovaries preserved in PBS for 8 h and electrically activated. The activated oocytes were then cultured in NCSU23 embryo culture medium for 16 h to observe activation or 144 h to observe embryo development. It was found that the preservation temperature affected the maturation of porcine oocytes greatly. The effect was described as a compromise of the suppressions of autolysis at physiological temperature and frostbite because of low temperature. A preservation temperature of approximately 25°C showed the maximum maturation rate for a preservation time of 8 h. Preservation temperature also affected the activation and embryo development of porcine oocytes greatly, following a trend similar to the effect of preservation temperature on the maturation. Based on maturation rate, activation rate and cleavage rate, a preservation temperature of approximately 25°C would be optimum for a preservation time of 8 h.

Gender does not influence epsilon-aminocaproic acid concentrations in adults undergoing cardiopulmonary bypass.

Epsilon-aminocaproic acid (epsilon-ACA) is administered to cardiac surgery patients to reduce blood transfusions. Highly water-soluble drugs, such as epsilon-ACA, often have larger distribution volumes in males than in females. We hypothesized that epsilon-ACA concentrations using this dosing scheme would differ by gender because of differences in body composition and weight-adjusted volumes of distribution. Ten men and 10 women undergoing elective coronary artery surgery with cardiopulmonary bypass (CPB) received a 50 mg/kg epsilon-ACA initial dose over 20 min and a 25 mg. kg(-1) x h(-1) epsilon-ACA maintenance infusion for 4 h. The area under the epsilon-ACA arterial concentration versus time curves was compared by using analysis of variance. Measured epsilon-ACA concentrations were smaller than predicted by the published model, but the area under the concentration versus time curves was not significantly different between men and women. Combining the present concentration data with that previously published, our updated two-compartment model included the following estimated population pharmacokinetic values: V(1) (11.8 L pre-CPB, 14.9 L during and after CPB), V(2) (12.0 L pre-CPB, 15.0 L during and after CPB), Cl(1) (0.125 L/min pre-CPB, 0.037 L/min during CPB, 0.156 L/min after CPB), Cl(2) (0.155 L/min pre-CPB, 0.013 L/min during CPB, 0.193 L/min after CPB).

Purification and characterization of an endotoxin-binding protein with protease inhibitory activity from Limulus amebocytes.

Using a lipopolysaccharide affinity column and ion exchange chromatography, a 12-kDa protein has been purified from Limulus amebocytes. In solid phase binding assays, the radiolabeled protein binds specifically to lipopolysaccharide (LPS) with a Kd value on the order of 10(-7) M. A cDNA coding for this protein has been isolated and sequenced. The amino acid sequence deduced from the cDNA indicates that this protein shares no sequence homology with LPS-binding proteins isolated from different species of vertebrates (Schumann, R. R., Leong, S. R., Flaggs, G. W., Gray, P. W., Wright, S. D., Mathison, J. C., Tobias, P. S., and Ulevitch, R. J. (1990) Science 249, 1429-1431) and invertebrates (Aketagawa, J., Miyata, T., Ohtsubo, S., Nakamura, T., Morita, T., Hayashida, H., Miyata, T., Iwanaga, S., Takao, T., and Shimonishi, Y. (1986) J. Biol. Chem. 261, 7357-7365). The binding to LPS can be displaced by the unlabeled 12-kDa protein, polymyxin B, lipid A, and to a lesser extent by D-glucosamine. In whole cell binding assays, the 12-kDa protein has also been shown to bind to Escherichia coli. Using both [14C]casein and a synthetic substrate, the protein has been shown to inhibit the proteolytic activity of trypsin, with an IC50 of approximately 10(-7) M. In the presence of LPS, the antitryptic acitivity of the Limulus endotoxin-binding protein-protease inhibitor remains unaffected. The protein is a major component of the cytoplasmic proteins (1%). Immunocytochemical analysis reveals that this protein exists in the secretory granules of the amebocytes where enzymes and substrates for the clotting cascade reside. Based on the unusual dual functional properties, the newly isolated protein was named a "Limulus endotoxin-binding protein-protease inhibitor" (LEBP-PI).

Effects of recombinant human interleukin-1 beta on rabbit articular chondrocytes. Stimulation of prostanoid release and inhibition of cell growth.

Using an in vitro model, we characterized the production of prostaglandin E2, 6-keto-prostaglandin F1 alpha, and thromboxane B2 by normal rabbit articular chondrocytes stimulated by interleukin-1 beta. The prostanoids were produced in a dose- and time-dependent manner, which was sensitive to actinomycin D and cycloheximide. Interleukin-1 also had a pronounced, but reversible, cytostatic effect on chondrocytes, which was not attributable to prostanoid or polyamine synthesis.

Muteins of human interleukin-1 that show enhanced bioactivities.

Using recombinant DNA techniques, we have made a series of amino-terminal muteins of human interleukin-1 (IL-1). Two of the muteins demonstrated 4-7-fold increase in bioactivity as compared to that of the native IL-1. The enhanced biological potency coincides with an increase in both receptor binding affinity and in vivo tumor inhibitory activity. By site specific mutagenesis, we have shown that the arginine at the fourth position of IL-1 is one of the key residues in the function of IL-1. Circular dichroism studies of the amino-terminus analogs showed little structural rearrangement. The change in bioactivity might be due to a change in the stability of the muteins, in the side chain interactions with receptors or in the minor change in folding near the receptor binding site.