A model for quantitative changes in the magnetic resonance parameters of muscle in children after therapeutic irradiation

Purpose/ObjectiveThis study aimed to develop objective models of radiation effects on musculature in children with soft tissue sarcoma using treatment dosimetry and clinical and quantitative magnetic resonance imaging (MRI) parameters that may be used to guide treatment planning or predict side effects.MethodsIn the initial 13 patients undergoing external beam radiation therapy (RT) on a Phase II study of conformal or intensity-modulated RT for the treatment of soft tissue sarcoma approved by an Institutional Review Board, we evaluated quantitative MRI changes in the musculature to assess radiation-related treatment effects. Patients with soft tissue sarcoma, including Ewing's sarcoma, had quantitative T₁, T₂ and dynamic enhanced MRI (DEMRI) performed before, during (Week 4) and after RT (Week 12). Regions of interest were selected in consistent locations within and outside the high-dose regions (on ipsilateral and contralateral sides when available). Mean RT dose, T₁, T₂ and DEMRI parameters were calculated and modeled using a mixed random coefficient dose model.ResultsThe mean doses to the high- and low-dose regions were 56.4 Gy (41.8–75.3 Gy) and 13.0 Gy (0.1–37.5 Gy), respectively. Compared with tissues distant from the tumor bed, maximal enhancement was significantly increased in tissues adjacent to the tumor/tumor bed prior to RT (60.6 vs. 44.2, P=.045) and remained elevated after 12 weeks. T₁ was significantly elevated in tissues adjacent to the tumor bed prior to RT (942.4 vs. 759.0, P=.0078). The slope of longitudinal change in T₁ was greater for tissues that received low-dose irradiation than those that received high-dose irradiation (P=.0488). The effect of dose on the slope of T₂ was different (P=.0333) when younger and older patients are compared.ConclusionsAcute affects of irradiation in muscle are quantifiable via MRI. These models provide evidence that quantifiable MRI parameters may be correlated with patient parameters of radiation dose and clinical factors including patient age. Long-term follow-up will be required to determine if acute changes correlate with clinically significant late effects.     

Determination of small phosphorus-containing compounds by capillary electrophoresis

The review focuses on the analysis of small phosphorus-containing compounds by capillary electrophoresis (CE) with different detection modes including UV absorption, laser-induced fluorescence, conductometry, amperometry, atomic spectrometry, and mass spectrometry. Determinations of phosphates, organophosphate, and chemical warfare agents in environmental samples such as water, soil and grains are emphasized. To achieve better sensitivity, high-resolving power, and reproducibility, the optimum separation conditions for various analytes (samples) are different. We compare the merits and demerits of the different detection modes for the detection of the analytes. Although the present methods are successful in many cases, there is still a need to develop high-throughput CE techniques for screening numerous environmental samples and sample stacking techniques in CE for the analysis of trace analytes.     

Immunoaffinity capillary electrophoresis: determination of binding constant and stoichiometry for antibody-antigen interaction

Affinity capillary electrophoresis (ACE) can provide both qualitative and quantitative information on molecular interactions and affords the advantages of very low sample consumption, high mass sensitivity, short analysis time, and the use of automated instrumentation. It has been applied clinically and biochemically to the determination of the binding constant and to the measurement of the binding stoichiometry for interactions between antibodies (Ab's) and antigens (Ag's) in free solution. In many situations, the Ag molecule has two or multiple binding sites, each of which has a similar or different intrinsic affinity for binding independently to the combining site(s) on an Ab molecule. The multivalent binding reactions between Ab and Ag molecules often occur. The objective of this review is to describe the uses of ACE in the determination of binding constants and stoichiometry of Ab-Ag interactions (immunoaffnity capillary electrophoresis), focusing especially on multivalent Ab-Ag interaction modes. Five model binding systems developed recently using ACE techniques are described with principles and examples: (i) divalent mAb-monovalent Ag interaction, (ii) divalent mAb-(homo)polyvalent Ag interaction, (iii) cooperativity of two binding sites of mAb-monovalent Ag interaction, (iv) monovalent Fab-divalent Ag interaction, and (v) polyclonal Ab-monovalent Ag interaction. Finally, the determination of binding stoichiometry of Ab-Ag interactions by ACE is described.     

On-line concentration of trace proteins by pH junctions in capillary electrophoresis with UV absorption detection

Hydroxylamine is a key raw material used in a synthetic drug process at Pharmacia. Since hydroxylamine is harmful to microorganisms, concentrations above 5 ppm could interfere with the biological sewage plant performance. This necessitated the development of a sensitive analytical method for detecting low levels of hydroxylamine in the waste streams generated from the pharmaceutical process. The present report describes a cation-exchange chromatographic method coupled with pulsed amperometric detection at a gold electrode for trace analysis of hydroxylamine. This method was evaluated by generating data on the parameters of specificity, precision, linearity, recovery and sensitivity.     

Nanoparticle-filled capillary electrophoresis for the separation of long DNA molecules in the presence of hydrodynamic and electrokinetic forces

We report the analysis of long DNA molecules by nanoparticle-filled capillary electrophoresis (NFCE) under the influences of hydrodynamic and electrokinetic forces. The gold nanoparticle (GNP)/polymer composites (GNPPs) prepared from GNPs and poly(ethylene oxide) were filled in a capillary to act as separation matrices for DNA separation. The separations of lambda-DNA (0.12-23.1 kbp) and high-molecular-weight DNA markers (8.27-48.5 kbp) by NFCE, under an electric field of -140 V/cm and a hydrodynamic flow velocity of 554 microm/s, were accomplished within 5 min. To further investigate the separation mechanism, the migration of lambda-DNA was monitored in real time using a charge-coupled device (CCD) imaging system. The GNPPs provide greater retardation than do conventional polymer media when they are encountered during the electrophoretic process. The presence of interactions between the GNPPs and the DNA molecules is further supported by the fluorescence quenching of prelabeled lambda-DNA, which occurs through an energy transfer mechanism. Based on the results presented in this study, we suggest that the electric field, hydrodynamic flow, and GNPP concentration are the three main determinants of DNA separation in NFCE.     

The effects of co-lyophilized polymeric additives on the glass transition temperature and crystallization of amorphous sucrose

The purpose of this study was to measure the effect of co-lyophilized polymers on the crystallization of amorphous sucrose, and to test for a possible relationship between the ability of an additive to raise theT _g of a sucrose-additive mixture, relative to theT _g of pure sucrose, and its ability to inhibit crystallization. Differential scanning calorimetry was used to measure the glass transition temperature,T _g, the non-isothermal crystallization temperature,T _c, and the induction time for crystallization,Q, of sucrose in the presence of co-lyophilized Ficoll or poly(vinylpyrrolidone) (PVP). The effect of these polymers on the crystallization of sucrose was significant as demonstrated by a marked increase inT _c, and in the induction time (Q) in the presence of relatively small amounts (1–10%) of additive. Surprisingly, small amounts of polymeric additive had no effect on theT _g of sucrose, although at higher concentrations, theT _g increased proportionally. Thus, it appears that the inhibition of sucrose crystallization by the additition of small amounts of a higher-T _g component cannot be attributed solely to changes in molecular mobility associated with an increase inT _g.     

Effect of Lactobacillus challenge on Gardnerella vaginalis biofilms

Bacterial vaginosis (BV) is the most common infectious condition in women. It is caused primarily by anaerobic bacteria which rapidly form biofilms recalcitrant to antibiotic treatment, elevate vaginal pH, induce inflammatory processes and displace indigenous lactobacilli from the vault. Gardnerella vaginalis is commonly associated with these infections. Microscopy analysis showed that within 72 h, viable G. vaginalis covered a surface area of 567 μm², reached a depth of 16 μm and a density of approximately 104 μm³. They maintained these levels for a further 3 days unless challenged with lactobacilli strains. Lactobacillus reuteri RC-14 produced the biggest displacement of Gardnerella. This was not due to pH, which remained between 4.7 and 5.1 for all experiments, nor by hydrogen peroxide which is produced in low amounts by strain L. reuteri RC-14, high amounts by L. crispatus 33820 and not at all by L. rhamnosus GR-1. Deconvolution microscopy showed changes in structure and viability of the biofilms, with loss of dense Gardnerella biofilm pods. For the first time, a strain of L. iners, the most commonly isolated vaginal Lactobacillus in healthy women, was tested for potential probiotic properties. It was found to disrupt Gardnerella biofilm surface area, density and depth, albeit to a lesser extent than L. reuteri RC-14. These studies help to provide insight into the clinical situation in which probiotic and indigenous vaginal lactobacilli can interfere with Gardnerella's presence and reduce the risk of bacterial vaginosis.     

Synthesis and characterisation of liquid crystal molecules based on thieno [3,2-b] thiophene and their application in organic field-effect transistors

A thieno [3,2-b] thiophene-based planar liquid crystal molecule, C₁₂-PTTT, which possesses the characteristics of an organic field-effect transistor (OFET), was synthesised and its mesomorphic properties were studied by polarising optical microscopy and differential scanning calorimetry. A wide temperature range for a highly oriented smectic phase was observed. OFET devices made under various conditions, such as self-assembled monolayer treatment and alignment treatment, and with micro-channel structures, were fabricated to measure the electrical properties. Among different OFET device conditions, the best electric carrier mobility for C₁₂-PTTT was 0.038 cm²?V^?1?s^?1.