Temperature-controlled power modulation compensates for heterogeneous nanoparticle distributions: a computational optimization analysis for magnetic hyperthermia

Purpose: To study, with computational models, the utility of power modulation to reduce tissue temperature heterogeneity for variable nanoparticle distributions in magnetic nanoparticle hyperthermia.

Methods: Tumour and surrounding tissue were modeled by elliptical two- and three-dimensional computational phantoms having six different nanoparticle distributions. Nanoparticles were modeled as point heat sources having amplitude-dependent loss power. The total number of nanoparticles was fixed, and their spatial distribution and heat output were varied. Heat transfer was computed by solving the Pennes’ bioheat equation using finite element methods (FEM) with temperature-dependent blood perfusion. Local temperature was regulated using a proportional-integral-derivative (PID) controller. Tissue temperature, thermal dose and tissue damage were calculated. The required minimum thermal dose delivered to the tumor was kept constant, and heating power was adjusted for comparison of both the heating methods.

Results: Modulated power heating produced lower and more homogeneous temperature distributions than did constant power heating for all studied nanoparticle distributions. For a concentrated nanoparticle distribution, located off-center within the tumor, the maximum temperatures inside the tumor were 16% lower for modulated power heating when compared to constant power heating. This resulted in less damage to surrounding normal tissue. Modulated power heating reached target thermal doses up to nine-fold more rapidly when compared to constant power heating.

Conclusions: Controlling the temperature at the tumor-healthy tissue boundary by modulating the heating power of magnetic nanoparticles demonstrably compensates for a variable nanoparticle distribution to deliver effective treatment.     

Cocrystal and Salt Forms of an Imidazopyridazine Antimalarial Drug Lead

Cocrystallization and salt formation were used to produce new multicomponent forms of a novel antimalarial imidazopyridazine drug lead (MMV652103) that displayed improved physicochemical properties. The drug lead had earlier shown good in vitro potency against multidrug resistant (K1) and sensitive (NF54) strains of the human malaria parasite Plasmodium falciparum, and high in vivo efficacy in both Plasmodium berghei and Plasmodium falciparum mouse models. A major drawback of MMV652103 is its limited aqueous solubility. Various new supramolecular products, including several multicomponent solid forms, are reported here, namely 3 cocrystal forms with the dicarboxylic acid coformers adipic acid, glutaric acid, and fumaric acid, and a salt form with malonic acid. These were characterized by thermal methods and their structures elucidated by single-crystal X-ray diffraction. A customized solubility experiment was performed in fasted-state simulated intestinal fluid for comparison of the solubility behavior of each new form of the drug lead with that of the untreated starting material. All of the multicomponent forms showed an improvement in the maximum concentrations (C_max) attained by the drug lead and the rate at which it dissolved. The recorded C_max values exceeded the concentration of the untreated compound by factors in the range 4.6-5.6.     

含功能性油的水飞蓟宾超饱和自纳米乳的制备与体外评价

目的制备含功能性油的水飞蓟宾超饱和自纳米乳(SLB-S-SNEDDS),并对其进行表征及体外评价研究,以提高难溶性药物水飞蓟宾的生物利用度。方法铁氢化钾还原力与1,1-二苯基-2-苦肼基(DPPH)自由基清除实验筛选功能性油脂;伪三元相图考察乳化剂乳化能力;测定粒径、多分散指数(PDI)、Zeta电位等考察混合油相比例与载药量;相容性与溶出度实验筛选促过饱和物质并考察其质量浓度;从外观、粒径分布、自乳化效率、形态学等方面表征SLB-S-SNEDDS,并进行溶出度、抗氧化能力、细胞毒性等体外评价。结果所得SLB-S-SNEDDS处方为(1)小麦胚芽油/Capryol 90-Cremophor ELP-Transcutol HP与(2)沙棘籽油/Capryol 90-Cremophor ELP-Transcutol HP,1 g基质(包含0.043 g小麦胚芽油或沙棘籽油、0.387 g Capryol 90、0.380 g Cremophor ELP、0.190 g Transcutol HP),水飞蓟宾的添加量为各组分平衡溶解度之和的20%,Soluplus的添加量为上述总质量的0.1%。小麦胚芽油、沙棘籽油体系分别为淡黄色、亮黄色透明状均一液体,2种体系自乳化分散后均呈近球形白色扁平乳滴,粒径约为50 nm,乳化时间均为65 s。与药物原料及SLB-SNEDDS相比,SLB-S-SNEDDS中水飞蓟宾的累积溶出率8h内均维持在85%～110%,表明该体系能够显著提高药物的溶出度。SLB-S-SNEDDS与铁氰化钾反应后的吸光度(A值0.452～0.782,0.488～0.765)以及DPPH自由基清除率(39.09%～96.02%,30.54%～89.20%)均高于相应质量浓度下水飞蓟宾原料的A值与清除率(0.411～0.760,22.89%～63.21%),表明2种处方体系均能提高水飞蓟宾的抗氧化能力。细胞毒性实验结果显示,在5、10μmol/L药物浓度下,水飞蓟宾原料组、水飞蓟宾S-SNEDDS组及其相应的空白S-SNEDDS组细胞生存率均90%,说明SLB-S-SNEDDS及其所用辅料对人克隆结肠腺癌细胞(Caco-2)毒性较小、安全性较好。结论制备的含功能性油SLB-S-SNEDDS在提高水飞蓟宾累积溶出率的同时,增强了其抗氧化能力,为将超饱和自纳米乳(S-SNEDDS)用于改善难溶性药物水溶性及其生物活性提供有益参考。     

姜黄色素-共聚维酮共研磨粉体性质及溶出度研究

目的 以姜黄色素为模型药物，考察辅料共聚维酮在共研磨过程中的应用特性及共研磨产物提高难溶性药物姜黄色素体外溶出方面的可行性。方法 采用共研磨法，在姜黄色素粉末中分别加入0%、1%、3%共聚维酮，制成不同比例的共研磨物，通过激光粒度仪及扫描电子显微镜（SEM）对其粒径形态进行考察；运用差示扫描量热法（DSC）、SEM和X射线粉末衍射法（XRPD）鉴别药物在共研磨物中的物相状态；测定姜黄色素原料药、物理混合物和共研磨物在2种溶出介质中的体外溶出度，并考察其加速稳定性。结果 与原料药相比，共聚维酮共研磨物粉末粒径减小，吸湿性和DSC无明显变化；XRPD中姜黄色素主要峰强度有所减弱，结晶度降低；共研磨物中姜黄色素的主要成分溶出度显著提高，在加速条件下放置3个月后溶出未发生变化，稳定性较好。结论 共聚维酮作为新型辅料，其与姜黄色素共研磨后得到的产物能有效改善难溶性药物姜黄色素的溶出度，且稳定性较好；为提高难溶性药物的溶解度和口服生物利用度提供了一种可行的策略。     

Water condensation from gas outlet of oxygenator

Condensation and water loss from gas output of the cardiopulmonary bypass (CPB) oxygenator has been the study object of several research. However, little is known about the propagation of the condensation formed at the level of oxygenator and how potentially it can contaminate the surrounding environment. We aimed to document the moment of formation of the ‘gas steam’ derived from the CPB oxygenator during cardiac surgery with thermography imaging. Thermographic camera is a device that creates an image using infrared radiation, similar to a common camera that forms an image using visible light. The brightest (warmest) parts of the image are customarily colored white, the intermediate temperatures reds and yellows, and the dimmest (coolest) parts black. Thermal image captures the condensation phenomenon around the oxygenator perimeter with the same color/temperature code (yellow) of gas outlet. The use of aspiration at the level of the gas outlet could also favor the elimination of the condensation, improve gas exchanges, and potentially reduce the spread of hazardous substances in the operating room.     

Important Parameter Groups in Thermal Protection of Polymers

The problem of thermal protection is explored for two idiosyncratic reactive systems, namely a sacrificial heat-sink material and an intumescent system where a dynamically evolving insulation layer is produced from an initially thin coating. Relatively simple mathematical models of both systems are proposed that encompass the important physical characteristics of each situation and these models are analysed using a mixture of numerical and analytical techniques. Important dimensionless parameter groups are identified and domains of parameter space where thermal performance is particularly good- or particularly bad- are identified.     

不同氢溴酸右美沙芬口服固体制剂的溶出度考察

目的：对6个厂家不同氢溴酸右美沙芬口服固体制剂进行体外溶出度考察，比较体外溶出情况，为临床用药提供参考。方法：采用转篮法，转速100 r·min^-1，用高效液相色谱法测定氢溴酸右美沙芬口服固体制剂在0.1 mol·L^-1盐酸溶液中的溶出曲线；以威布尔方程拟合溶出参数T₅₀、T_d、m，并对参数进行方差分析。结果：氢溴酸右美沙普通片、分散片、胶囊以及软胶囊的平均累积溶出度分别为94.3%、101.3%、105.2%、93.4%。溶出参数T₅₀、T_d差异较大，其中T₅₀最大的是最小的13.4倍。结论：氢溴酸右美沙片、分散片、胶囊以及软胶囊体外溶出行为差别大，产品质量存在较大差异。