In vivo EBT radiochromic film dosimetry of electron beam for Total Skin Electron Therapy (TSET)

EBT radiochromic films were used to determine skin-dose maps for patients undergone Total Skin Electron Therapy (TSET). Gafchromic EBT radiochromic film is one of the newest radiation-induced auto-developing photon and electron-beam analysis films available for therapeutic radiation dosimetry in radiotherapy applications. EBT films can be particularly useful in TSET; due to patient morphology, underdosed regions typically occur, and the radiochromic film represents a suitable candidate for monitoring them.In this study, TSET was applied to treat cutaneous T-cell lymphoma. The technique for TSET was implemented by using an electron beam with a nominal energy of 6 MeV. The patient was treated in a standing position using dual angled fields in order to obtain the greatest dose uniformity along the patient's longitudinal axis. The electron beam energy was degraded by a PMMA filter. The in vivo dose distribution was determined through the use of EBT films, as well as of thermoluminescent dosimeters for comparison (TLDs). EBT results showed a reasonable agreement with TLDs data.     

Evaluation of Gafchromic® EBT3 films characteristics in therapy photon,electron and proton beams

PurposeTo evaluate the uncertainties and characteristics of radiochromic film-based dosimetry system using the EBT3 model Gafchromic^® film in therapy photon, electron and proton beams.Material and methodsEBT3 films were read using an EPSON Expression 10000XL/PRO scanner. They were irradiated in five beams, an Elekta SL25 6 MV and 18 MV photon beam, an IBA 100 MeV 5 × 5 cm² proton beam delivered by pencil-beam scanning, a 60 MeV fixed proton beam and an Elekta SL25 6 MeV electron beam. Reference dosimetry was performed using a FC65-G chamber (Elekta beam), a PPC05 (IBA beam) and both Markus 1916 and PPC40 Roos ion-chambers (60 MeV proton beam). Calibration curves of the radiochromic film dosimetry system were acquired and compared within a dose range of 0.4–10 Gy. An uncertainty budget was estimated on films irradiated by Elekta SL25 by measuring intra-film and inter-film reproducibility and uniformity; scanner uniformity and reproducibility; room light and film reading delay influences.ResultsThe global uncertainty on acquired optical densities was within 0.55% and could be reduced to 0.1% by placing films consistently at the center of the scanner. For all beam types, the calibration curves are within uncertainties of measured dose and optical densities. The total uncertainties on calibration curve due to film reading and fitting were within 1.5% for photon and proton beams. For electrons, the uncertainty was within 2% for dose superior to 0.8 Gy.ConclusionsThe low combined uncertainty observed and low beam and energy-dependence make EBT3 suitable for dosimetry in various applications.     

Terbinafine hydrochloride loaded liposome film formulation for treatment of onychomycosis: in vitro and in vivo evaluation

Onychomycosis is a fungal infection of nail unit that is caused by dermatophytes. Oral Terbinafine hydrochloride (TBF-HCl) is being used for the treatment of onychomycosis since 24 years. The side effects caused by the systemic application and limitations of topical administration of this drug regarding the diffusion through nail lead to the development of a new formulation based on, TBF-HCl-loaded liposome. The newly obtained film formulations were prepared and characterized via several parameters, such as physical appearance, drug content, thickness, bioadhesive properties and tensile strength. In vitro and ex vivo permeation studies were performed to select an optimum film formulation for antifungal activity to show the efficiency of formulations regarding the treatment of onychomycosis. The in vitro release percentages of drug were found 71.6?±?3.28, 54.4?±?4.26, 56.1?±?7.48 and 46.0?±?2.43 for liposome loaded pullulan films (LI-P, LII-P) and liposome loaded Eudragit films (LI-E, LII-E), respectively. The accumulated drug in the nail plates were found 31.16?±?4.22, 24.81?±?5.35, 8.17?±?1.81 and 8.92?±?3.37 for LI-P, LII-P, LI-E and LII-E, respectively, which within therapeutic range for all film formulations. The accumulated drug in the nail plate was found within therapeutic range for all film formulations. The efficacy of the selected TBF-HCl-loaded liposome film formulation was compared with TBF-HCl-loaded liposome, ethosome, liposome poloxamer gel and ethosome chitosan gel formulations. It was found that TBF-HCl-loaded liposome film formulation had better antifungal activity on fungal nails which make this liposome film formulation promising for ungual therapy of fungal nail infection.     

Ready-to-use thermally stable mastermix pills for molecular biology applications

Rolling circle amplification (RCA), polymerase chain reaction (PCR), and loop-mediated isothermal amplification (LAMP), are powerful tools that can be used for gene manipulation, pathogen detection, and infectious disease diagnostics. However, these techniques require trained personnel, as the pipetting steps involved can lead to contamination and, consequently, erroneous results. Furthermore, many of the reagents used in molecular biology are thermally labile and must be kept within a cold-chain. In this article, we present a simple and cost-effective method that allows molecular biology reagents to be thermally stabilized into ready-to-use mastermixes via drying in pullulan and trehalose films. Our experimental results demonstrate that this method is capable of preserving the activity of RCA, PCR, LAMP, ligase, polynucleotide kinase, and Klenow fragment mastermixes for at least 3 months at ambient conditions. Thus, stabilizing reagents via drying in pullulan and trehalose film may allow for a drastic reduction in the number of pipetting steps and the elimination of the need for a cold chain. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2764, 2019.     

应用FTIR和NMR研究短梗霉多糖分子结构

短梗霉多糖是出芽短梗霉产生的一种胞外多糖,具有极好的成膜、成纤维、阻气、粘接、易加工、无毒性等特性,是微生物多糖中最令人瞩目的多糖之一．本研究应用ＦＴＩＲ和ＮＭＲ技术对由出芽短梗霉胞外产生的短梗霉多糖进行了分析．短梗霉多糖的红外光谱（４０００～４００ｃｍ－１）,具有明显的多糖特征吸收峰,证明多糖是由α－Ｄ－吡喃葡萄糖残基组成．应用先进的一维和二维核磁共振技术,在绝对温度３４３Ｋ下获得短梗霉多糖１Ｈ－ＮＭＲ谱和１３Ｃ－ＮＭＲ谱,确证短梗霉多糖的结构单元是α－１,４麦芽三糖,归属了短梗霉多糖的１Ｈ和１３Ｃ的全部化学位移     

Synthesis and properties of pullulan acetate. Thermal properties, biodegradability, and a semi-clear gel formation in organic solvents

Pullulan acetate (AcPL) with various degree of substitution (DS: 1.0–3.0) was synthesized by the reaction of pullulan with acetyl chloride in the presence of pyridine. The product was characterized by gel permeation chromatography (GPC), infra-red (IR) and ¹H NMR spectroscopy. The weight average molecular weights of the products did not decrease less than 190,000 (GPC) in the acetylation reaction. Thermogravimetric analysis (TGA) revealed that AcPL has a higher decomposition temperature (306–363 °C) than unmodified pullulan (295 °C). Differential scanning calorimetry analysis (DSC) revealed that all the AcPLs exhibit a clear T_g, which decreased with increasing DS value in the range of DS 1.0–2.4. The AcPL with DS 2.4 showed the lowest T_g (153 °C), and the AcPL with DS 3.0 had a slightly higher T_g (163 °C). Tensile modulus of AcPL films was comparable to that of a popular cellulose acetate film. The biodegration rate of AcPL decreased with increasing degree of acetylation. The AcPL with DS 3.0 was found to form a semi-clear gel in organic solvents such as dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), and 1,4-dioxane.     

Properties of pullulan-based blend films as affected by alginate content and relative humidity

Pullulan-sodium alginate blend films were prepared and characterized as a function of water activity (a_w). At low a_w, the incorporation of alginate into pullulan film increased the tensile strength and elastic modulus, but decreased the elongation at break of the composite films; the opposite trends were observed at elevated a_w. Above 0.43 a_w, water exerted a typical plasticization effect upon the biopolymer blends. As a_w increased from 0.23 to 0.43, an anti-plasticization effect was observed as tensile strength and elastic modulus increased. The glass transition temperature of all samples decreased substantially as aw increased from 0.23 to 0.84 due to the plasticization effect of water. Within this a_w range, one transition temperature was observed for all film specimens. The stretching vibration band of O-H was investigated using attenuated total reflection Fourier transform infrared spectroscopy to identify the various species of water interacting with the polysaccharide films.     

High throughput film dosimetry in homogeneous and heterogeneous media for a small animal irradiator

PurposeWe have established a high-throughput Gafchromic film dosimetry protocol for narrow kilovoltage beams in homogeneous and heterogeneous media for small-animal radiotherapy applications. The kV beam characterization is based on extensive Gafchromic film dosimetry data acquired in homogeneous and heterogeneous media. An empirical model is used for parameterization of depth and off-axis dependence of measured data.MethodsWe have modified previously published methods of film dosimetry to suit the specific tasks of the study. Unlike film protocols used in previous studies, our protocol employs simultaneous multi-channel scanning and analysis of up to nine Gafchromic films per scan. A scanner and background correction were implemented to improve accuracy of the measurements. Measurements were taken in homogeneous and inhomogeneous phantoms at 220 kVp and a field size of 5 × 5 mm². The results were compared against Monte Carlo simulations.ResultsDose differences caused by variations in background signal were effectively removed by the corrections applied. Measurements in homogeneous phantoms were used to empirically characterize beam data in homogeneous and heterogeneous media. Film measurements in inhomogeneous phantoms and their empirical parameterization differed by about 2%–3%. The model differed from MC by about 1% (water, lung) to 7% (bone). Good agreement was found for measured and modelled off-axis ratios.ConclusionsEBT2 films are a valuable tool for characterization of narrow kV beams, though care must be taken to eliminate disturbances caused by varying background signals. The usefulness of the empirical beam model in interpretation and parameterization of film data was demonstrated.     

On the use of EBT3 film for relative dosimetry of kilovoltage X ray beams

EBT3 films were evaluated for relative dosimetry in water, in the energy range of therapeutic kV X ray beams. A film batch was calibrated in air for all nine beam qualities of a clinical unit (XStrahl 200). Monte Carlo (MC) simulations using MCNP v.6 facilitated the calculation of the film absorbed dose (f), and beam quality (k_bq) energy dependences in air. Results were found in agreement with corresponding data in the literature. Film samples from the same batch were irradiated in water along the central beam axis for each beam quality. Experimental percentage depth dose (PDD) results obtained using calibration data in air showed quality and depth dependent differences from corresponding MC simulations. These differences increased beyond film dosimetry uncertainty (<3.3%), reaching up to 8% at increased depth. The observed differences reduced only slightly when spectral variation as a function of measurement point was accounted for, using photon effective energy. PDD measurements and corresponding MC results facilitated the determination of f and k_bq in water. Results showed that the origin of the observed differences between experimental and MC PDD results is the difference between film response in air and water, as a result of radiation field perturbation from the film oriented along the central beam axis. This implies a directional dependence of film response which necessitates that the angular distribution of photons impinging on the film is the same in the calibration and measurement geometries.     

Interaction of gum arabic, maltodextrin and pullulan with lipids in emulsions

The interaction of gum arabic, maltodextrin and pullulan with lipids in emulsion systems was investigated. Interfacial tension and interfacial viscosity measurements revealed that only gum arabic could adsorb and form a viscoelastic film at the oil-water interface. Good emulsifying activity was demonstrated for gum arabic, whereas fine emulsions could not be produced from the other polysaccharide solutions and oil. Frequency-dependent increases in the storage and loss moduli were observed for all the polysaccharide solutions. Such rheological behavior did not substantially change when maltodextrin and pullulan were mixed with oil to form emulsions. However, the frequency-dependence of the dynamic moduli disappeared in the gum arabic-stabilized emulsion, suggesting the formation of a network structure in which oil droplets could form junctions with gum arabic chains. The results on the inhibition of lipid oxidation by polysaccharides suggest that gum arabic protected lipids from the attack of lipoxygenase and free radicals by adsorbing at the oil droplet surface.     

Comparison of methods for assessing geometric efficiency on multi-detector CT scanners

The aim of the current study was to compare the film method against the method based on a new CT slice detector in assessing geometric efficiency (GE) of x-ray beams utilized by a multi-detector CT (MDCT) scanner. Measurements of GE were performed using radiographic films and a solid state CT slice detector for all beam qualities, collimations and focal spot sizes available on an MDCT scanner. Repeatability of GE measurements was assessed. The radiographic film and the solid state detector methods were compared to each other in regard to efficacy in measuring free-in-air GE. The values of GE determined using the radiographic film method were found to range between 48.5% and 90.6%. Differences between values obtained with the radiographic film method and corresponding values obtained with the solid state detector were less than 10% exceeding 5% for only one case. Both methods show that wide beams have higher GE values compared to thin ones. The use of large instead of small focal spot was found to deteriorate GE values by up to 23.1%. Beam quality did not seem to influence GE of the various collimations. When thin beam collimations are employed, a considerable amount of the radiation is wasted for non-imaging purposes. Both film and solid state probe methods are capable of measuring GE of thin as well as wide collimations. The solid state detector is the easiest to use, however its usefulness is reduced by the fact that it cannot measure dose profiles of beam collimations available for step-and-shoot mode of operation.     

Estimation of pullulan by hydrolysis with pullulanase

A novel method for the estimation of pullulan was developed in which pullulan was hydrolysed by pullulanase. The hydrolysed product was mainly maltotriose and was determined colorimetrically using 3,5-dimethylsalicylic acid. This gave good linearity with respect to the concentration of pullulan in the fermentation broth. The content of pullulan determined in this way was less than that determined by a coupled enzyme assay and was comparable to that determined by an HPLC method. The new method was specific for estimation of pullulan, demonstrated high accuracy, and could assay pullulan from up to 3.2 mg/ml.     

Energy and dose dependence of GafChromic EBT3-V3 film across a wide energy range

AimTo determine the energy and dose dependence of GafChromic EBT3-V3 film over an energy range 0.2 mm Al HVL to 6 MV.BackgroundThe decay scheme of a brachytherapy source may be complex and the spectrum of energy can be wide. LiF TLDs are the golden standard recommended for dosimetric measures in brachytherapy, for their energy independence, but TLDs could be not available in some centres. An alternative way to perform dose measurements is to use GafChromic films, but they show energy dependence.Methods and materialsFilms have been irradiated at increasing dose with three different beams: 6 MV beam, TPR20, 10 = (0.684 ± 0.01), HVL = (2.00 ± 0.01)mmAl and HVL = (0.20 ± 0.01)mmAl. Calibration curves were generated using the same dose range (0cGy to 850cGy) for the three energies. Using the 6 MV calibration curve as reference, the film response in terms of net optical density (OD) was evaluated.ResultsThe difference in the calibration curve obtained by irradiating the film with 6 MV and 2 mm Al HVL energy beams is less than 3 %, within the calibration uncertainty, in the dose range 500-850cGy. The OD of EBT3-V3 film is significantly lower at 0.2 mmAl HVL compared to 6 MV, showing differences up to 25 %.ConclusionWithin the range 6 MV-2 mm Al HVL and dose higher than 500cGy, GafChromic EBT3-V3 films are energy independent. In this dose range, films can be calibrated in a simple geometry, using a 6 MV Linac beam, and can be used for brachytherapy sources dose measures. The use of EBT3 films can be extended to reference dosimetry in Ir-192 clinical brachytherapy.     

REDUCTION OF HEATING ARTIFACTS IN THIN SECTIONS EXAMINED IN THE ELECTRON MICROSCOPE

Certain phenomena affecting contrast obtained from tissue sections with the electron microscope have been investigated and a technique is described for reducing destruction by the electron beam of fine details in sections. It has been concluded that loss of embedding material is slightly higher at exposed surfaces of sections than it is at surfaces covered by substrate film. Covering of both surfaces of sections with thin films of formvar, collodion, or carbon materially improves the general appearance, reduces distortion, and sometimes reduces loss of tissue mass from the section as result of exposure to the electron beam. This improvement is considered to result from the relatively high melting-point of the covering films which serve to eliminate or reduce surface-tension or other forces operating in methacrylate softened by the electron beam.     

Disinfection of sewage sludge cake by an electron accelerator

Effects of radiation dose rate, electron energy and oxygen on disinfection of sewage sludge cake were studied to obtain technological information on disinfection by radiation. Sludge films were irradiated with electron beams at different voltages and various dose rates in oxygen-containing and oxygen-free atmospheres. Without oxygen, the surviving fraction of bacteria decreased with increasing irradiation dose, but depended little on the sludge film thickness. No effects of dose rate and energy change were found in the ranges from 20 kGy/h to 65 MGy/h and from 0.5 to 2.0 MeV when the film was thin enough to allow electron beam penetration. Similar results were obtained with γ-ray irradiation. In the oxygen-containing atmosphere, higher disinfection efficiency was obtained with thinner films and lower dose rates.     

Conjugation of heparin into carboxylated pullulan derivatives as an extracellular matrix for endothelial cell culture

A carboxylated pullulan, for use as a structural material for a number of tissue engineering applications, was synthesized and conjugated with heparin. By immobilization of heparin to pullulan, endothelial cells (ECs) attached on the heparin-conjugated pullulan were more aggregated than when attached to other pullulan derivatives. Attachments were 50, 45, 49, and 90% for a polystyrene dish, pullulan acetate, carboxylated pullulan, and heparin-conjugated pullulan, respectively. Heparin-conjugated pullulan inhibited the proliferation of smooth muscle cells (SMCs) in vitro. Heparin-conjugated pullulan material can thus be used for the proliferation of vascular ECs and to inhibit the proliferation of SMCs.     

出芽短梗霉色素变异菌株R45的普鲁蓝糖发酵研究

用正交实验确定了出芽短梗霉（Aureobasidiumpullulans）色素变异菌株R45的发酵优化条件。在此条件下,摇瓶培养的普鲁蓝糖产量最高可达82．4g／L,转化率为54．9％。实验表明,CaCO3是多糖发酵的重要影响因素,多糖的合成与发酵pH值及细胞形态密切相关。     

二价阳离子对短梗霉多糖发酵的影响

就二价阳离子对短梗霉多糖和黑色素的影响进行了分析和研究。结果表明 ,二价阳离子对短梗霉多糖的合成和黑色素的形成均有较大的影响。通过对培养基中二价阳离子含量和种类的控制不仅可以抑制细胞黑色素的形成 ,而且还保持了很高的多糖发酵水平 ,在 30L生物反应器中短梗霉多糖的产量和转化率分别达到了 59 8g/L和 61 5%。     

Pullulan Elaboration by Aureobasidium pullulans Protoplasts

Protoplasts of Aureobasidium pullulans are capable of producing pullulan. Biosynthesis of the polymer pullulan required induction with kinetics similar to those of whole cells. The protoplasts also produced a heteropolysaccharide component containing mannose, glucose, and galactose. The relative proportions of the pullulan and heteropolysaccharide fractions were a function of glucose concentration, with the pullulan content of the total polysaccharide rising from 20% at 2.5 mM glucose to 45% at 20 mM glucose. Elaboration of pullulan by both cells and protoplasts was sensitive to 0.6 M KCl, which was present as the osmotic stabilizer in protoplast experiments. The presence of KCl resulted in a shift in the pH optimum to a more acidic value. The molecular weight of the protoplast-derived pullulan was sharply reduced from the molecular weight of the whole-cell-derived product. Exposure of the protoplasts to proteolytic enzymes had no effect on polysaccharide elaboration.