Carboxymethylcellulose biofunctionalized ternary quantum dots for subcellular-targeted brain cancer nanotheranostics.

Among the most lethal forms of cancer, malignant brain tumors persist as one of the greatest challenges faced by oncologists, where nanotechnology-driven theranostics can play a critical role in developing novel polymer-based supramolecular nanoarchitectures with multifunctional and multi-modal characteristics to fight cancer. However, it is virtually a consensus that, besides the complexity of active delivering anticancer drugs by the nanocarriers to the tumor site, the current evaluation methods primarily relying on in vitro assays and in vivo animal models have been accounted for the low translational effectiveness to clinical applications. In this view, the chick chorioallantoic membrane (CAM) assay has been increasingly recognized as one of the best preclinical models to study the effects of anticancer drugs on the tumor microenvironment (TME). Thus, in this study, we designed, characterized, and developed novel hybrid nanostructures encompassing chemically functionalized carboxymethylcellulose (CMC) with mitochondria-targeting pro-apoptotic peptide (KLA) and cell-penetrating moiety (cysteine, CYS) with fluorescent inorganic semiconductor (Ag-In-S, AIS) for simultaneously bioimaging and inducing glioblastoma cancer cell (U-87 MG, GBM) death. The results demonstrated that the CMC-peptide macromolecules produced supramolecular vesicle-like nanostructures with aqueous colloidal stability suitable as nanocarriers for passive and active targeting of cancer tumors. The optical properties and physicochemical features of the nanoconjugates confirmed their suitability as photoluminescent nanoprobes for cell bioimaging and intracellular tracking. Moreover, the results in vitro demonstrated a notable killing activity towards GBM cells of cysteine-bearing CMC conjugates coupled with pro-apoptotic KLA peptides. More importantly, compared to doxorubicin (DOX), a model anticancer drug in chemotherapy that is highly toxic, these innovative nanohybrids nanoconjugates displayed higher lethality against U-87 MG cancer cells. In vivo CAM assays validated these findings where the nanohybrids demonstrated a significant reduction of GBM tumor progression (41% area) and evidenced an antiangiogenic activity. These results pave the way for developing polymer-based hybrid nanoarchitectonics applied as targeted multifunctional theranostics for simultaneous imaging and therapy against glioblastoma while possibly reducing the systemic toxicity and side-effects of conventional anticancer chemotherapeutic agents.

Comparison of brown midrib-6 and -18 forage sorghum with conventional sorghum and corn silage in diets of lactating dairy cows.

Total mixed rations containing conventional forage sorghum, brown midrib (bmr)-6 forage sorghum, bmr-18 forage sorghum, or corn silage were fed to Holstein dairy cows to determine the effect on lactation, ruminal fermentation, and total tract nutrient digestion. Sixteen multiparous cows (4 ruminally fistulated; 124 d in milk) were assigned to 1 of 4 diets in a replicated Latin square design with 4-wk periods (21-d adaptation and 7 d of collection). Diets consisted of 40% test silage, 10% alfalfa silage, and 50% concentrate mix (dry basis). Acid detergent lignin concentration was reduced by 21 and 13%, respectively, for the bmr-6 and bmr-18 sorghum silages when compared with the conventional sorghum. Dry matter intake was not affected by diet. Production of 4% fat-corrected milk was greatest for cows fed bmr-6 (33.7 kg/d) and corn silage (33.3 kg/d), was least for cows fed the conventional sorghum (29.1 kg/d), and was intermediate for cows fed the bmr-18 sorghum (31.2 kg/d), which did not differ from any other diet. Total tract neutral detergent fiber (NDF) digestibility was greatest for the bmr-6 sorghum (54.4%) and corn silage (54.1%) diets and was lower for the conventional (40.8%) and bmr-18 sorghum (47.9%) diets. In situ extent of NDF digestion was greatest for the bmr-6 sorghum (76.4%) and corn silage (79.0%) diets, least for the conventional sorghum diet (70.4%), and intermediate for the bmr-18 sorghum silage diet (73.1%), which was not different from the other diets. Results of this study indicate that the bmr-6 sorghum hybrid outperformed the conventional sorghum hybrid; the bmr-18 sorghum was intermediate between conventional and bmr-6 in most cases. Additionally, the bmr-6 hybrid resulted in lactational performance equivalent to the corn hybrid used in this study. There are important compositional differences among bmr forage sorghum hybrids that need to be characterized to predict animal response accurately.

Roles of Akt/PKB and IKK complex in constitutive induction of NF-kappaB in hepatocellular carcinomas of transforming growth factor alpha/c-myc transgenic mice.

NF-kappaB regulates liver cell death during development, regeneration, and neoplastic transformation. For example, we showed that oncogenic Ras- or Raf-mediated transformation of rat liver epithelial cells (RLEs) led to altered NF-kappaB regulation through IKK complex activation, which rendered these cells more resistant to TGF-beta1-induced apoptosis. Thus, based on these findings, we sought to determine whether NF-kappaB could also be involved in tumor growth of liver cells in vivo. Hepatocellular carcinomas (HCCs) derived from bitransgenic mice harboring TGF-alpha and c-myc transgenes targeted specifically to the liver were compared with HCCs from c-myc single transgenic mice. Tumors from bitransgenic mice are characterized by a higher frequency of appearance, lower apoptotic index, and a higher rate of cell proliferation. Here we show that NF-kappaB is activated in HCCs of double TGF-alpha/c-myc transgenic mice, but not of c-myc single transgenic mice, suggesting that TGF-alpha mediates induction of NF-kappaB. Activation of the IKK complex was observed in the HCCs of double TGF-alpha/c-myc transgenic mice, implicating this pathway in NF-kappaB induction. Lastly, activation of the Akt/protein kinase B (PKB), which has recently been implicated in NF-kappaB activation by PDGF, TNF-alpha, and Ras, was also observed. Importantly, human HCC cell lines similarly displayed NF-kappaB activation. Thus, these studies elucidate an anti-apoptotic mechanism by a TGF-alpha-Akt/PKB-IKK pathway, which likely contributes to survival and proliferation, thereby accelerating c-myc-induced liver neoplastic development in vivo.

Leaf position error during conformal dynamic arc and intensity modulated arc treatments.

Conformal dynamic arc (CD-ARC) and intensity modulated arc treatments (IMAT) are both treatment modalities where the multileaf collimator (MLC) can change leaf position dynamically during gantry rotation. These treatment techniques can be used to generate complex isodose distributions, similar to those used in fix-gantry intensity modulation. However, a beam-hold delay cannot be used during CD-ARC or IMAT treatments to reduce spatial error. Consequently, a certain amount of leaf position error will have to be accepted in order to make the treatment deliverable. Measurements of leaf position accuracy were taken with leaf velocities ranging from 0.3 to 3.0 cm/s. The average and maximum leaf position errors were measured, and a least-squares linear regression analysis was performed on the measured data to determine the MLC velocity error coefficient. The average position errors range from 0.03 to 0.21 cm, with the largest deviations occurring at the maximum achievable leaf velocity (3.0 cm/s). The measured MLC velocity error coefficient was 0.0674 s for a collimator rotation of 0 degrees and 0.0681 s for a collimator rotation of 90 degrees. The distribution in leaf position error between the 0 degrees and 90 degrees collimator rotations was within statistical uncertainty. A simple formula was developed based on these results for estimating the velocity-dependent dosimetric error. Using this technique, a dosimetric error index for plan evaluation can be calculated from the treatment time and the dynamic MLC leaf controller file.

Role of the IkappaB kinase complex in oncogenic Ras- and Raf-mediated transformation of rat liver epithelial cells.

NF-kappaB/Rel factors have been implicated in the regulation of liver cell death during development, after partial hepatectomy, and in hepatocytes in culture. Rat liver epithelial cells (RLEs) display many biochemical and ultrastructural characteristics of oval cells, which are multipotent cells that can differentiate into mature hepatocytes. While untransformed RLEs undergo growth arrest and apoptosis in response to transforming growth factor beta1 (TGF-beta1) treatment, oncogenic Ras- or Raf-transformed RLEs are insensitive to TGF-beta1-mediated growth arrest. Here we have tested the hypothesis that Ras- or Raf-transformed RLEs have altered NF-kappaB regulation, leading to this resistance to TGF-beta1. We show that classical NF-kappaB is aberrantly activated in Ras- or Raf-transformed RLEs, due to increased phosphorylation and degradation of IkappaB-alpha protein. Inhibition of NF-kappaB activity with a dominant negative form of IkappaB-alpha restored TGF-beta1-mediated cell killing of transformed RLEs. IKK activity mediates this hyperphosphorylation of IkappaB-alpha protein. As judged by kinase assays and transfection of dominant negative IKK-1 and IKK-2 expression vectors, NF-kappaB activation by Ras appeared to be mediated by both IKK-1 and IKK-2, while Raf-induced NF-kappaB activation was mediated by IKK-2. NF-kappaB activation in the Ras-transformed cells was mediated by both the Raf and phosphatidylinositol 3-kinase pathways, while in the Raf-transformed cells, NF-kappaB induction was mediated by the mitogen-activated protein kinase cascade. Last, inhibition of either IKK-1 or IKK-2 reduced focus-forming activity in Ras-transformed RLEs. Overall, these studies elucidate a mechanism that contributes to the process of transformation of liver cells by oncogene Ras and Raf through the IkappaB kinase complex leading to constitutive activation of NF-kappaB.

A comparison of beam characteristics for gated and nongated clinical x-ray beams.

Respiratory gating has only recently been applied to conventional external beam radiotherapy. In order for respiratory gating to be used clinically, an evaluation of the dosimetric effects of small units of delivered dose must be performed. The purpose of this study is to systematically evaluate the effect of various gating sequences on x-ray central axis output, ionization ratios (nominal accelerating potential), beam flatness, and beam symmetry. Measurements were taken for 6 and 18 MV photons on a linear accelerator that generates the gate by using a gridded electron gun to stop the electron flow to the wave-guide. The beam output, energy, flatness, and symmetry did not vary by more than 0.8 percent in most of the gating sequences. The maximum output deviations (0.8 percent), flatness deviations (1.9 percent), and symmetry deviations (0.8 percent) occurred when a low number of monitor units (<5 MU) were delivered in the gating window. Although these deviations are not clinically significant, each linear accelerator should be evaluated carefully before clinical implementation.

Clinical application of digitally-reconstructed radiographs generated from magnetic resonance imaging for intracranial lesions.

PURPOSE: The purpose of this work is to demonstrate the clinical utility of magnetic resonance (MR) imaging-based digitally reconstructed radiographs (DRRs) for the setup and verification of patients with intracranial lesions. METHODS AND MATERIALS: MR images of 16 patients with various intracranial lesions were obtained for treatment planning and virtual simulation. Five-millimeter-thick contiguous T1-weighted postcontrast transverse slices were obtained using a standard head coil in a General Electric Signa 1.5T MR scanner. MR-DRRs were generated using the "pseudo density" technique on an existing treatment planning computer without any special modifications. Anterior and lateral verification films were taken for each patient for visual comparison with MR-based DRRs. RESULTS: Visual alignment with bony landmarks, including the orbits, frontal sinus, sphenoid sinus, auditory meatus, nasal bone, vomer bone, mastoid process, and the cranium were used by physicians, physicists, and therapists to verify patient positioning. Misalignments from 3 to 10 mm were visually identified and corrected using this technique. CONCLUSION: A method for visually utilizing MR-based DRRs during simulation has been developed and clinically implemented. The quality of MR-DRRs generated using this technique is such that physicians, physicists, and therapists can easily and routinely compare MR-DRRs side-by-side with simulation films.

Factors affecting the production of L-phenylacetylcarbinol by yeast: a case study.

L-Phenylacetylcarbinol (L-PAC) is the precursor for L-ephedrine and D-pseudoephedrine, alkaloids possessing alpha- and beta-adrenergic activity. The most commonly used method for production of L-PAC is a biological method whereby the enzyme pyruvate decarboxylase (PDC) decarboxylates pyruvate and then condenses the product with added benzaldehyde. The process may be undertaken by either whole cells or purified PDC. If whole cells are used, the biomass may be grown and allowed to synthesize endogenous pyruvate, or the cells may be used as a catalyst only, with both pyruvate and benzaldehyde being added. Several yeast species have been investigated with regard to L-PAC-producing potential; the most commonly used organisms are strains of Saccharomyces cerevisiae and Candida utilis. It was found that initial high production rates did not necessarily result in the highest final yields. Researchers then examined ways of improving the productivity of the process. The substrate, benzaldehyde, and the product, L-PAC, as well as the by-products, were found to be toxic to the biomass. Methods examined to reduce toxicity include modification of benzaldehyde dosing regimes, immobilization of biomass or purified enzymes, modification of benzaldehyde solubility and the use of two-phase reaction systems. Various means of modifying metabolism to enhance enzyme activity, relevant metabolic pathways and yield have been examined. Methods investigated include the use of respiratory quotient to influence pyruvate production and induce fermentative activity, reduced aeration to increase PDC activity, and carbohydrate feeding to modify glycolytic enzyme activity. The effect of temperature on L-PAC yield has been examined to identify conditions which provide the optimal balance between L-PAC and benzyl alcohol production, and L-PAC inactivation. However, relatively little work has been undertaken on the effect of medium composition on L-PAC yield.

Dosimetric verification of two commercially available three-dimensional treatment planning systems using the TG 23 test package.

The Task Group 23 (TG-23) radiation treatment planning dosimetry verification package was used to evaluate the dosimetric accuracy of two commercially available treatment planning systems. The TG-23 test package contains experimentally measured beam data for two x-ray beams (4 and 18 MV) that can be used as input for 3D-RTP (three-dimensional radiation treatment planning) systems. Once the beam data is entered and modeled, a series of test cases are performed that isolate different aspects of the dose computational process. The computed values from the 3D-RTP system are compared against the measured dosimetry data, included in the package, for a set of comparison points within each test case. Both of the treatment planning systems that were studied provided excellent agreement between computed and measured doses. The cumulative 4 and 18 MV TG-23 test results for the convolution/superposition based planning system indicates that 96% of the dosimetric test points are within +/-2%, and 98% are within +/-3% of the tabulated TG-23 values. The dosimetric TG-23 test results for the pencil beam kernel based planning system are similar, with 96% of the test points falling within +/-2%, and 99% falling within +/-3% of the TG-23 measurements.

Clinical efficacy of respiratory gated conformal radiation therapy.

One major limitation of three-dimensional conformal radiation therapy that has not been adequately addressed is respiration-induced organ motion. During respiration, tumors in the abdomen can typically move from 1 to 3 centimeters. Because the size and shape of external radiation treatment fields do not change during treatment, the field size of the x-ray beam must be enlarged to encompass the tumor through the entire respiration cycle. Several manufacturers are developing respiratory gating systems. These systems allow the selective delivery of absorbed doses to moving target volumes in the abdomen during time intervals when the target volume is within the intended location. Before respiratory gated radiotherapy can be implemented clinically, the efficacy of the procedure must be justified. The magnitude of dosimetric and geometric uncertainties associated with respiratory motion must be identified to determine if gating can provide an advantage over conventional treatment techniques. In addition, clinical situations and specific types of cancer that could benefit from respiratory gating must also be identified.

Ionization chamber, electrometer, linear accelerator, field size, and energy dependence of the polarity effect in electron dosimetry.

Plane-parallel ionization chambers are the instrument of choice for use in electron calibration and dosimetry, but these chambers may exhibit large polarity effects. This study concentrates on measuring the dependence of the polarity error at various mean energies using different linear accelerator, field size, ion chamber, and electrometer combinations. The polarity error was shown to increase for all four ionization chambers as the mean energy at depth decreased, but was always less than one percent at d(max). Polarity error dependence was also observed for similar plane-parallel chambers, varying field sizes, and different linear accelerators, but no polarity error dependence was observed for similar cylindrical chambers and different electrometers. Measurements of the polarity error can be used to develop correction factors for future measurements that will help minimize the time spent performing electron dosimetry and calibrations. These correction factors can be used to calculate the correct reading without the need to reverse the chamber bias, thus reducing the number of measurements required.

Magnetic resonance imaging based digitally reconstructed radiographs, virtual simulation, and three-dimensional treatment planning for brain neoplasms.

Currently, patients with brain neoplasms must undergo both computed tomography (CT) and magnetic resonance (MR) imaging to take advantage of CT's density information and MR's soft tissue imaging capabilities. A method has been developed that allows virtual simulation, digitally reconstructed radiographs (DRRs), and 3-D treatment planning of patients with brain neoplasms to be generated using only one T1-weighted MR data set. DRRs of an anthropomorphic RANDO head phantom were generated using MR and CT imaging. The MR based DRRs provided structural information equivalent to CT based DRRs. The spatial linearity of CT and MR image sets was evaluated by measuring the percent distortion and spatial error. There was no statistical difference in spatial linearity or accuracy between the CT and MR image sets. MR and CT based treatment planning were compared using a variety of different treatment accessories, field sizes, photon energies, and gantry positions. Doses at various points throughout the head phantom were used as comparison points between CT based heterogeneous, CT based homogenous, and MR based homogenous treatment planning of the head phantom. Lithium fluoride thermoluminescent dosimeters were used to verify the dosimetric accuracy of MR based treatment planning by taking measurements at these points. For treatment plans with fields that pass through large air cavities, such as the maxillary sinus, homogenous treatment planning produces unacceptable dosimetric error (2%-4%). For treatment plans with fields that pass through the skull, MR homogenous treatment planning can be used with a dosimetric accuracy of +/- 2%.

A network approach to outpatient service delivery systems: resources flow and system influence.

OBJECTIVE: The study tests a path model for the effects on organizational influence of an organization's centrality in four resource exchange networks in order to gain insight into the network relations that may affect coordination and effectiveness of outpatient health and mental health service systems. DATA SOURCES: Primary data are used from face-to-face interviews with the directors of every organization in the predefined service systems in three urbanized counties in Oregon. Each system consisted of 19 to 20 organizations. Data were collected during 1986 and 1987. STUDY DESIGN: The path model contains five variables: the major dependent variable is attributed organizational influence; the independent variables are three sets of primary resource exchanges: funds allocation, client referrals, and client inflow. An intervening variable of general network contacts, as an informational resource, is modeled as an outcome of the three primary resource exchanges, as well as one of the predictors of influence. DATA COLLECTION: Organizations were identified as system members through a modified snowball sampling procedure. Measures of organizational influence and centrality in each of the exchange networks were derived from interviews with all directors about their interactions with each organization in the system. Multiple regression analysis was used to test the path model. PRINCIPAL FINDINGS: The most important resource in predicting centrality in a general contact network is centrality in a client referral network, while contacts and funds allocation centrality are significant predictors of organizational influence. CONCLUSIONS: The organization with the greatest influence within the system (because of its ability to allocate funds) may not be the organization that takes the largest role in terms of coordinating routine contacts (because of its ability to refer clients). This disjuncture may signal a weakness in the coordination network and system effectiveness, since the more influential organization may not be the most knowledgeable one in terms of the needs of the system.

A ballistic evaluation of the impact resistance of spectacle lens materials.

The impact resistance of chemically and thermally hardened glass lenses of 2.2- and 3.0-mm thicknesses was evaluated using a ballistic test. Each lens was edged and mounted into a spectacle frame, which was placed on a standard headform. A 6.5-mm steel ball was fired from an air gun at the center of the lens at increasing speeds until the lens broke. The multiple impact data were used to plot cumulative breakage curves. We found that heat-treated photochromic glass and heat-treated crown glass fail at similar missile speeds and that chemical treating considerably improves the impact resistance of crown glass but not of photochromic glass. The poorer performance of photochromic lenses indicates that they should not be prescribed when optimal impact protection is required. Plastic lenses show superior performance.